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Languages of the Stage

by: Georgianna Bode

Languages of the Stage THE 2005

Georgianna Bode
GPA 3.82


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This 79 page Class Notes was uploaded by Georgianna Bode on Wednesday September 23, 2015. The Class Notes belongs to THE 2005 at University of South Florida taught by Staff in Fall. Since its upload, it has received 13 views. For similar materials see /class/212622/the-2005-university-of-south-florida in Theater Arts at University of South Florida.


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Date Created: 09/23/15
Agenda item Board Office to complete USF Board of Trustees December 2 2004 Issue USFFlorida State Golf Association s partnership agreement for sublease and operations of USF golf course Proposed action Approve of the Sun Dome Inc request for permission to negotiate a partnership arrangement with the Florida State GolfAssociation to make the golf course the state headquarters for the FSGA and to build the Florida Golf House Background information The current USF Master Plan designates this land as the University Golf Course which is bordered on the east by the USF Ecological Research Area Therefore the CDC recommends approval to continue use of the land as a golf course Consistent with that the CDC recommends USF immediately pursue and negotiate a partnership arrangement with FSGA to operate the golf course as their state headquarters contingent upon the University reaching an acceptable agreement with FSGA on the following issues USF should negotiate a Partnership arrangement to Provide continued support of USF activities on the golf course Maintain USF related alliances Address current contractual relationships such as Exclusive Beverage Sponsorship Agreement Accommodate any existing research in the adjacent land Address potential disturbance of archeologically signi cant sites as required by statute through the USF Archeology Department Address responsibility of mitigating natural resource impacts Address responsibility and liability of use of water for irrigation under the current Water Use Permit Address potential fees that may be assessed to USF for impacts to the level of service of the host community s infrastructure due to planned improvements Specify the term ofthe agreement Address the terms of a buyback option Upon reaching a satisfactory partnership agreement provide for all necessary documentation for proposed improvements to be included in the 2005 Master Plan Update including traffic and environmental impacts 0 Include a land survey of boundaries easements and natural features of the proposed sublease of land 0 Be structured in such a way as to facilitate and foster casual use ofthe facilities by students Workgroup Review ACE Workgroup CDC Supporting documentation Proposal PowerPoint Presentation to the Campus Development Committee by Michael Rierson Prepared by Barbara Donerly on behalf of the CDC 813 9743103 valGame A squuoamse Am MA m w m a r Proposal for USF Campus Development Committee July 20 2004 Executive Summary The Claw at USF golf course has received a proposal from the Florida State Golf Association FSGA to make the golf course the state headquarters for the FSGA and build the Florida Golf House which is a Hall of Fame for state golf The FSGA is proposing to spend upwards of 9 Million to upgrade the course to a premier facility USF s contribution will be to lease the land the golf course currently sits on The renovation would take place from AprilDec 2006 Upon completion the FSGA would assume operations and management of The Claw and thus retain all resulting revenues and profits SUNDOME lnc would eliminate any loss potential from golf course operations and the USF Men s and Women s golf programs would secure use of a premier facility thus helping recruiting Raising the stature and conditions The Claw would yield additional benefits to the University for Alumni and Development initiatives A condition ofthe partnership is to secure up to 10 acres of wetlands adjacent to the existing golf course This land would be used to reconfigure a few golf holes in orderto make room for proper practice facilities and clubhouse that meets FSGA standards This proposal is being brought before the USF Campus Development Committee to secure permission to pursue the partnership The Claw at USF Florida State Golf Association Partnership Project Background The Claw at USF wwwtheclawatusforg is a 35 year old moderately priced golf course that generates 4000050000 rounds of golf per year The course is located adjacent to the main USF campus on Fletcher and 46m St and in a very advantageous centrally located geographic area easily accessible to a large populationgolfer base The Claw as it is known has always been recognized as one of the best dailyfee layouts in the Tampa Bay area and is well regarded for its natural surroundings absent of any oncourse housing development that is typical ofthe newer courses in the area The Claw is one ofthe few area courses that allow walkers at all times a time honored tradition in golf and has always enjoyed the support of the local golf community As is typical of all area golf courses The Claw sees the majority of profitable business in the winter tourism months and has lower activity in the warm summer months when rates for all courses are reduced The Claw is a community asset that serves a diverse user base where many private courses still can be exclusive due to cost and location The University has also benefited from the close proximity ofthe course Students faculty staff and alumni use the course extensively and a number of campus related tournaments leagues fundraising events University golf classes and even a cross country meet are held at the course The course is also home to the USF Men s and Women s Golf Programs with team facilities lockers and meeting rooms located at the course In addition the golf course restaurant Rocky s Sports Grill is a frequent campus stop for lunch as well as student socializing and has become part of campus life The Claw has also played a role in entertaining donors who golf Many top universities such as Duke Stanford Michigan and Ohio State boast some of the finest courses in their markets and there is no doubt that The Claw has the potential to be in that same class In the past 5 years the golf market has become increasingly competitive and this along with the lack of discretionary funds to reinvest in the condition of The Claw has challenged it to remain profitable Because golfers have more quality choices greens fees have been moderated in order to attract a steady flow of golfers in order to keep the course busy In the summer of 2003 The Claw embarked on a 1 million renovation from state appropriated funds for a water mitigation project These funds were used to improve overall drainage systems and runoff from the greens A new irrigation system was also installed throughout the golf course resulting in better conditions year round While the improvements mentioned above have brought the course backto playable conditions and business is improving significant renovations estimated at 25 million are still required to fulfill the potential ofthe golf course and deliver a product worthy of the increased greens fees that will be needed to bring the course to profitability Since it appears that University resources are not available to invest in this effort we have explored other opportunities to move the facility to optimum condition Florida State Golf Association The FSGA wwwfsgaorg is a nonprofit volunteer based organization that has served amateur golf in Florida since 1913 The mission ofthe FSGA is to preserve and protect the integrity ofthe game of golf in Florida The FSGA includes over 775 member clubs and over 160000 individual members from across the state FSGA is currently located in Tampa at Hidden River Corporate Park on Fletcher Avenue The FSGA provides a variety of services to member clubs their members and the general golfing community FSGA conducts more than 100 tournament days each year including 21 state championships and 41 days of USGA qualifying events FSGA also actively cooperates with the United States Golf Association the PGA of America the Florida Women s State Golf Association the International Association of Golf Administrators the Golf Course Superintendents Association and all other golfserving organizations Because Florida has more golf courses that any other state the FSGA commands quite a lofty presence in the national golf community FSGAUSF Partnership The Florida State Golf Association has approached SUNDOME Inc and the University seeking a partnership which would bring the FSGA headquarters to The Claw FSGA has already had their Board of Directors visit the course and has also had a noted golf architect assess the course FSGA is proposing that SUNDOMEUSF and FSGA combine resources to completely renovate the course add a modern practice facility and develop a new club houseFSGA Golf House which would also include a Hall of Fame for Florida Golf Accomplishing the project would require the appropriation of up to 10 acres of additional land adjacent to the golf course FSGA is proposing an estimated 9 million project and will fund the entire renovation USF s contribution will be the land The renovation would take place from April Dec 2006 Pursuing this partnership would culminate in the FSGA assuming operations and management of The Claw and thus retain all resulting revenues and profits The FSGA would operate Florida Golf House conduct training and hold major state golf events at The Claw USF would inherit a premier golf facility with a National Audubon site designation for the campus and SUNDOME lnc would eliminate any loss potential from golf course operations Positives 0 Will bring a very prestigious partner under USF umbrella and create another differentiation point among national universities 0 Will insure USF has an A rated golf course connected with the University as well as the best facility in The Big East 0 FSGA stature as well as tournaments held at the course will attract national attention in golfing circles o Environmentally will improve drainage and any hazardous chemical runoff The new course would qualify for certification from the Audubon Cooperative Sanctuary Program 0 Will make the USF golf facility a must play option for golfing tourists o FSGA Board members and supporters become a potential new donor group to USP 0 Creates a prime campus specific location to entertain and impress large donors 0 Will elevate men s and women s golf team recruiting into the top echelon in the nation 0 Will provide the existing golf programs with premier facilities and rentfree space for locker rooms coaches offices and team meeting space 0 FSGA community activities teaching and promoting the game of golf to lower income groups will reflect positively on US 0 Opens the real potential to develop a Professional Golf Management program at USP 0 USF golf classes would be conducted at a premier learning center 0 The new golf course coupled with the new facilities will allow the course to host better quality and larger fundraising golf events assuming FSGA intends to pursue such events 0 Would provide the best scenario for realizing a significant profit due to the ability to increase average daily fees and at the same time maximize the rounds played 0 SUNDOME removes loss potential from the golf course and any additional investment requirements Ability to draw larger and more prestigious events to the course and area Could become another positive component in recruiting faculty and staff The deal will maintain a golf course at USF as a permanent facility As an additional ROI incentive for the University we would also recommend the partnership include financial support for the intercollegiate golf team programs Concerns While there may be some negative implications we feel many of them can be addressed as below 0 As the deal currently stands there is no financial ROI guaranteed USF turns over the course to the FSGA with the rewards being the prestige of FSGA affiliation and development of an A golf facility Response In its present state and without further investment our best case scenario is a breakeven business 0 Loss of control Flexibility to serve USF students and organizations may become limited For example holding a cross country track meet on the course or USF related tournaments Response In their proposal FSGA has already indicated they will continue to support USF activities We intend to negotiate assurances that this will be the honored 0 Any intent to utilize the golf course for other USF uses would require a significant buyout Response This will require some longterm thinking from the Trustees and philosophical agreement that a golf facility adds a special value to the University 0 Some ofthe current business building alliances we have forged may be lost tournaments alumni groups campus leagues tourism Response Any USF related alliances will be maintained It will be FSGA s business decision to continue any other activities No negative impact is expected o It will take adjustment to USF master plan Response Of the 570 acres of property we are only asking for up to 10 acres 0 Land may be getting used by Biology Department or other University Research groups Response Every attempt would be made to accommodate any existing research or move it to similar areas 0 Downtime for the golf course and staffing issues would create another profitability issue Response FSGA would assume control of the facility once construction begins Construction may be done in phases to eliminate disruption of play 0 Financial impact on Athletics due to taking on golf coaches salaries Response Construction is not scheduled until April of 2006 and thus the matter of Golf Coaches salary allocation will hopefully have been finalized 0 Men s and Women s Golf programs will need temporary practice facilities Response A shortterm solution with a local course or multiple courses will be accomplished 0 Possible impact on USF golf classes during renovation Response We will attempt to schedule the range renovation during the summer months to minimize any impact The estimated time for the entire renovation process is AprilDec 2006 Besides the land use issue the decision to move forward appears to hinge on the issue of control If USF Administration and Trustees feel comfortable about relinquishing control of the facility and it is enough of a return in prestige and amenities to end up with a premium golf facility the deal is a winwin for all Some major assurances will need to be negotiated to insure USF students and golf teams maintain access Recommendation We recommend USF begin negotiation to finalize a partnership with FSGA in order to establish the USF Golf Course as the home to FSGA Golf House Florida By bringing the home of Florida s amateur golf community to USF we will take the first step towards raising the USF Golf Facilities to a higher level of prominence and recognition From a marketing perspective USF ends up with a superior facility at no cost and the FSGA affiliation will act as another national image building component for USF Through this agreement the USF Golf Facilities will be greatly enhanced as the course will become one of the finest daily fee facilities in the area The Florida Golf House will become a must see destination for any golfer visiting the area and there is only one FSGA headquarters golf facility which provides a distinctive edge for The Claw Michael D Rierson University of South Florida Vice President Advancement Michael R LaPan CFE SUN DOME Inc Executive Director James J Fee The Claw at USF Director of Golf UNIVERSITY OF SOUTH FLORIDA Florida State Golf Association Proposal October 14 2004 Opportunity FSGA to bring Florida G0 USF Golf Course v USF Mission Student Centered Environment Creates a special amenity for students and staff Research Joint research opportunities with FSGA amp Audubon Golf industry development a core goal of FSGA Fiscal selfsufficiency Create a positive return to USF Cultural and Community Life Signi cant opportunity for USF and community interaction Pin quotI 3 3921 ilvzlrquot quotfiu I can UNIVERSITY OF SOUTH FLORIDA History of Built 1968 120 acres Reputation as one of the finest layouts in the Tampa Bay area Serves USF and Tampa community as dailyfee golf course hosting an average of 45K50K rounds per year Home to USF Men s and Women s Golf Programs Hosts USF golf classes UNIVERSITY OF SOUTH FLORIDA Current Situation Competitive Industry National golf rounds in decline since 2000 Extensive course renovations by competing courses The Claw 800000 loss over past 3 years 200405 breakeven projected prehurricanes USF Golf Operation continues to support USF Golf Programs 192000yr 7 r d a W I Recent renovation improved my C i a course conditions and helped bolster business UNIVERSITY OF SOUTH FLORIDA 3 FSGA Overview Notforprofit governing body of amateur golf in Florida Established 1913 775 member clubs amp over 160000 individual members Conducts over 100 tournament days per year including 21 state championships Mission Preserve and protect the integrity of Florida golf UNIVERSITY OF SOUTH FLORIDA USFFSGA Partnership FSGA will build Florida Golf House replacing existing limited facilities with larger clubhouse new conference facility office space and larger restaurant Obtains the ability to develop up to 10 acres of land adjacent to the golf course FSGA will invest up to 9 million in golf course and facilities renovation FSGA proposes land lease and assumes control of golf course in mid2005 UNIVERSITY OF SOUTH FLORIDA Proposed Plan UNIVERSITY OF SOUTH FLORIDA Area Overview UNIVERSITY OF SOUTH FLORIDA Bene ts To USF Eliminates future exposure to industry uctuations and de cits Brings professional management resources of FSGA National Audubon Site designation environmentally improves entire golf course site Enhances recruiting for USF Golf Programs UNIVERSITY OF SOUTH FLORIDA Bene ts to USF Provides stateoftheart teaching facilities and expanded capacity for USF golf classes Estimated 104Kyr in current golf class fees Brings strong affinitydonor group to USF amp Foundation USF community has access to a superior facility FSGA will act as another image building component for USF UNIVERSITY OF SOUTH FLORIDA Great University Great Golf Course uwlvsksnv RUTGERS UNIVERSITY r OLF COURSE WSTATE UNIVERsmLquot39J s v r quot g 7 UNIVERSITY OF SOUTH FLORIDA Issues amp Concerns Ownership Partnership would involve lease agreement with USF maintaining ownership of property Environmental Seeking to use least amount of land and least pristine in an environmentally friendly manner Proposed land use adjacent to existing Tampa Palms easement Potential property mitigation Master Plan Renovation may coincide with master plan update UNIVERSITY OF SOUTH FLORIDA Issues amp Concerns Agreement will incorporate existing USF contractual obligations and requirements including Beverage agreement Water use permits and restrictions Governmental ordinances and regulations Where applicable Traffic Flow 46th St already scheduled for 3 lanes by County Fletcher Ave and 46th St turn lane Golf course has handled more rounds in previous years UNIVERSITY OF SOUTH FLORIDA What we don t know Yet Cost of any mitigation associated with the 10 acre expansion Extent of financial compensation to USF Business Assessment value of the deal UNIVERSITY OF SOUTH FLORIDA Estimated Timeline November 2004 ACEUBOT approval December 2005 or earlier FSGA assumes operations control April 2006 Golf course construction begins December 2006 New course opens Spring 2007 FSGA Golf House Florida opens 3 UNIVERSITY OF SOUTH FLORIDA Recommendations Conceptual approval of FSGA Proposal with recommendation to ACE workgroup and UBOT to proceed with FSGA partnership negotiations Recommendations for leasing guidelines Length of lease term Returned revenue ow to USF Buyback guarantee as well as amortization of the FSGA I investment and future valuation I technique regarding land value I f Others 39 54 gt4 3 m quotx V T i SOUTH FLORIDA UNIVERSITY OF SOUTH FLORIDA High Latitude Changes in Ice Dynamics and Their Impact on Polar Marine Ecosystems Mark A Moline Nina Karnovskyf Zachary Brownb George Divoky Thomas K Frazerd Charles AJacobyd Joseph Torresf and William R Fraserf lIBiological Sciences Department and Center for Coastal Marine Sciences California Polytechnic State University San Luis Obispo Cali ornia USA bDepartnient ofBiology Pomona College Claremont California USA cInstitute ofArctic Biology University ofAlaska Fairbanks Fairbanks Alaska USA dDepartment of Fisheries and Aquatic Sciences Institute of Food and Agricultural Sciences University of Florida Gainesville Florida USA eDepartment of Marine Sciences University of South Florida St Petersburg Florida USA f Polar Oceans Research Group Sheridan M ontana USA Polar regions have experienced signi cant warming in recent decades Warming has been most pronounced across the Arctic Ocean Basin and along the Antarctic Peninsula with signi cant decreases in the extent and seasonal duration of sea ice Rapid retreat of glaciers and disintegration of ice sheets have also been documented The rate of arming is increasing and is predicted to continue well into the current century with continued impacts on ice dynamics Climatemediated changes in ice dynamics are a 39 39 y habitat for 39 39 to the food webs of 39 39 extent of pa 39 39 L Changes in l 1 and spatial separations between energy requirements and food availability for many higher trophic levels These mismatches lead to decreased reproductive success lower abundances and changes in distribution In addition to these direct impacts of ice loss climateinduced changes also facilitate indirect effects through changes inhydrography which include introduction of species from lower latitudes and altered assemblages of primary producers Here we review recent changes and trends in ice dynamics and the responses of marine ecosystems Speci cally we provide examples of icedependent organisms and associated species from the Arctic and Antarctic to illustrate the impacts of the temporal and spatial changes in ice dynaInics Key words polar ecosystems climate change sea ice trophic cascade matchi mismatch pheno ogy 39I Introduction The Earth s atmosphere is warming Over the past 100 years the average temperature has increased by approximately 06 C IPCC Address for correspondence MarkA Moline Biological Sciences De partment and Center for CoastalMarine Sciences California Polytechnic State University San Luis Obispo CA 98407 Voice 178057756r2948 fax 40780577567141 9 molinemarine calpolyedu 2001 Since the mid1970s the rate of atmo spheric warming has nearly doubled and global warming trends are forecast to continue IPCC 2001 2007 These forecasts generate signi cant concern as polar regions are especially vul nerable in global climate change scenarios with even relatively small deviations in atmospheric temperatures profoundly in uencing oceano graphic and ecological processes Concerns extend from the effects of these increased Ann NY Acad Sci 1134 267 31 9 2008 2008 New York Academy of Sciences 0 doi101196annuls143901 268 atmospheric temperatures on the timing and extent ofseasonal seaice formation in both the Arctic and Antarctic regions to the conse quences for organisms that are linked to these dynamics by nature of their life histories Sea ice coverage is in fact declining Liu et a1 2004 Yuan 2004 Serreze et a1 2007 This is a con cern as sea ice serves as an essential habitat in polar ecosystems with components of the system requiring the ice as substrate for con sistent light and chemical environments as a source for prey and as a general resource for part or all ofmany organisms life cycles In ad dition to documented broadscale declines in sea ice there has been a signi cant retreat of coastal glaciers and ice sheem increasing the degree of oceanographic strati cation in these regions with further in uences on important ecological processes and interactions Changes in global climate are not manifest uniformly thus there is likely to be signi cant variability in the location and timing of warming with an asymmetric in uence on ice dynamics and ocean processes Polar ecosystems respond to these heterogeneous regional changes within a relatively brief window suitable for growth and reproduction Winder amp Schindler 2004 Therefore the issue of scale both spatial and temporal cannot be ignored when examining these especially pronounced trophic interac tions This paper reviews the recent changes and trends in ice dynamics and observed and predicted responses in the Arctic and Antarctic marine ecosystems 11 Seaice Dynamics Over an annual cycle large expanses of sea water in the highlatitude marine environments undergo the cycle of freezing and melting In winten sea ice covers up to 7 00 ofthe earth s sur face In general sea ice forms as a relatively thin layer up to 3 mthick but ridges up to 20 m thick can form Sea ice acts as a physical barrier to oceaniatmosphere exchange of gases ie oxy gen and carbon dioxide and to the uxes of heat and moisture Sea ice prevenm direct con Annals of the New York Academy of Sciences tact between the relatively warm ocean and the colder atmosphere During winten when the temperature gradients between the surface ocean and atmosphere are maximaL the loss of heat to the atmosphere can be up to two orders of magnitude smaller over seaice cover than in open ocean With its high albedo the ice and its snow cover reduce the amount ofin coming solar radiation absorbed at the ocean surface by re ecting much of it back to space The transfer of momentum from the atmo sphere to the ocean which in uences upper ocean currents is also modi edby the presence of ice The annual formation of sea ice is critical to the movement of ocean currents worldwide Salt rejected from the ice structure during its formation and growth increases the salinity and density of the underlying waten which can in uence the formation ofbottomwater that con tributes to the upwelling of nutrients and to the overall thermohaline circulation on continen tal shelves and in the deep ocean Following the initial freezing of sea waten sea ice is con tinually modi ed by the interaction of physical biological and chemical processes to form an extremely heterogeneous semisolid matrix It is within this matrix that seaice biota thrive When the sea iceiwhich is considerably less salty than sea waterimelts in spring fresher water is released forming a stable lowsalinity surface layer that can affect primary produc tion Despite the general similarities in the an nual cycle of sea ice the dynamics between the Arctic Ocean and the Southern Ocean differ signi cantly The Antarctic is unbounded at its northern extent with a very deep continental shelf mar gin As a result sea ice undergoes cyclical pe riods of convergence and divergence under the in uence of winds and ocean currents North of 650S the sea ice generally moves from west to east in the Antarctic Circumpolar Cur rent but with a net northward component of drift The unconstrained nature of the Antarc tic sea ice results in a large annual range in geographic extent from 3 to 18 million km2 Molina el al Changes in Ice Dynamics and Polar Marine Ecosyslems Sea ice Concentration a Fi ure 1 MGleUm and mlmmum SeEHCe cover forlhe A B Arena and C D Amorch Boreolwmr d lerisdepicle or om poles on Melehpanes Wl le ouslrolwmler 15 on the ngMpanels The black males in the center of the Northern emlsp are images are areas lacking dam due to llmll llons in satellite cover age cHhe North Pole lmoge courtesy owe Nollonol Snow on lce Dam Center Umverslly of Co orodo Boulder Colorado ln color in Annas onlme over the summer minimum and winter maxi mum respectively Fig 1 Because ofthis large seasonal varia 39 ity on y a comparatively small fraction of the sea ice persism more than one season In contrast the Arctic is composed of predominantly landlocked shallow shelf seas w 39 re 39 39 39 ke ce The extent of the Arctic sea ice swells to almost 14 million km2 in the Win ter with the summer minimum approximately 40 of the winter maximum Fig 1 The ex tent and thickness of the perennial multiyear ice however has been signi cantly decreasing see below he melting process is another difference between Arctic an Antarctic sea ice In the Arctic the sea ice melm at the surface form ing melt pools increasing absorption of solar radiation and enhancing the melt process In the Antarctic melting occurs from contact with the ocean on the bottom and sides of the ice Openingsin seaice develop and increase in size 269 as the surface layer of the ocean warms The interplay between macronutrienm and trace el ements particularly iron within the two polar regions so Va The andwcean exchange in the Antarctic is restricted due to t e po lar ice cap and ice shelves extending into the ocean Sea ice is therefore largely sediment free W1 39 arely exhausted As the Arctic is generally landloc e the ocean is supplied with trace el ements from river runoffand from atmospheric deposition of dust During ice formation sea ice incorporates these sedimentparticles which ar later available to primary producers upon m ting As a result of this source of iron in tense Arctic production along the gins unlike the ntarctic is limited by nitrate Smetacek amp Nicol 2005 e el seaice mar 392 Present Trends in Largescale Ice Dynamics Sea ice is relatively thin and is therefore vul nerable to small perturbations by the ocean andor atmosphere These disturbances can signi can y alter the extent and thickness of the cover and the rates of seaice formation and melting Such changes have been docu mented in both polar regions and the current rate of climate warming As the physical and chemical dynamics of both sys tems are distinct the impacts ofcurrent climate change and the ecosystem responses are also ried 121 The Arctic Ocean Over the past few decades the Arctic seaice cover has signi cantly decreased in spatial tent Analyses oftemperature records and sea ice cover between 1961 and 1990 showed a sig ni cant and distinctwarming thatwas strongest over northern land areas during the winter and spring Chapman amp Walsh 1993 In an 11 year record from 1978 to 2000 Comiso 2002a found the rate ofArctic perennial seaice cover ex 270 Annals of the New York Academy of Sciences 9 8 IE 3 7 E 5 s a 2 a a 39 5 4 mm 1978 1982 1986 1990 1994 1998 2002 2006 Year Figure 2 September Amttc seortce extent from 1979 to 2007 showmg o ptectpttous decltne The September tote at seortce ecltne stnce 1979 ts now approxtmotely W per decade ot720001ltm2 Untvetstty at Colorado Boulder Colorado decline to be relatively fast at 89 i 20 per decade This rate coincided with a positive trend in the ice temperature of about 12 C per decade leading to earlier onset of melt retreat ofperennial ice cover and delayed on set of ice formation Parkinson 2002a 2006 These changes have been documented ious regions a 12 decrease in April seaice extentin the Kara Sea from 1953 to 1990 Di vine 52 a1 2003 a decrease in the Barenm Sea sea ice from 1850 to 2001 Shapiro 52 a1 2003 and increased rate ofmelting in the Bering Sea from 1971 to 2001 Hunt 52 a1 2002Johan nessen and colleagues 2004 identi ed two pro nounced 20thcentury warming events which were ampli ed in the Arctic and linked to vari ability in seaice Observations and model simu I c J I39 I that in var the nature ofthe warmingin the past 20 yearsis distinct from the earlier warm period Stroeve 52 a1 2007 and strongly suggested the recent temperature changes are in response to anthro pogenic forcing whereas earlier warming was linked to natural internal climatesystem var39 ability The area of Arctic sea ice decreased petyeot lmogecoutt esy at the Nattonal Snow and lee Data Center about 75 from 1978 to 2003 with an ini tial record low summer extent in 2002 Serreze 52 a1 2003Johannessen 52 a1 2004 Since this record in 2002 seaice extent has continued to decrease with new record minima in 2005 and the dramatic loss observed in September 2007 Fig 2 Furthermore Serreze and colleagues 2007 found that the decreases were not re stricted to summer months occurring through out the year from 197972006 The progressive retreat of perennial ice has been asymmetric with signi cantly higher losses in the Chukchi Sea and adjacent areas Fig 3A In contrast seaice cover in Ba in Bay and Davis Strait from 1953 to 2001 was found to be largely unchanged and correlated with each previous winter North Atlantic Oscillation index Stern amp U quotl T 03 Although sea ice in this region has not decreased consistently data indicate that even these areas of lower ability have experienced recent losses Fig 3A These regional differences are thought to be linked to anumber ofprocesses Fig 4 regional warming differences Chapman amp Walsh 1993 Serreze 52 a1 2007 Stroeve 52 a1 2007 vari Moline et al 2007 39 39 2005 mlnlmu m 792000 median minimum 0 39 50 Changes in Ice Dynamics and Polar Marine Ecosystems t 39 s 4 Figure 3 A We spatral arstrrbutron ot tne seortce extent tn tne Aratra Ocean on September to 2007 compared to tne 2005 mrnrmum green me 2000 yellow tme The filled red circle tndtc m Uence of tire Larsoan lee Shelf collo green ondMotch tune Orzooz compare in color tn Annas onltne anomalous cloud cover NSIDC 2007 atmo spheric forcing amp Wallaoe 2007 and ocean circulation patterns Proshutinsky 52 a1 1999 Shapiro 52 a1 2003 The fact that the seaice retreat has largely occurred in the pri mary openings to the Arctic Ocean in the Bar ents and Chukchi Seas illustrates the impor tance of ocean circulation This is consistent with studies showing the extent ofseaice tied to warmer water intrusions from the Norwegian Sea into the Barents Sea Saloranta amp Svend sen 2001 Shapiro 52 a1 2003 and Chukchi Sea Mizobata amp Wang 2006 and the anticy clonic circulation patterns in the Chukchi Sea Proshutinsky 52 a1 1999 T environmental feedbacks associated with changes in seaice have also been explored The loss ofperennial sea ice at the time ofpeak solar radiation has been found to decrease the surface albedo allowing more solar heating of the upper ocean Fig 4 An increase in the so lar energy deposited in the upper ocean over the past few decades was found in 89 of the an t e mean ates tne loaatron of se along tne Antaratra Penrnsula tn lonuoty yellow February wrtn tne mean we coveraurrng tnesame montns tn 1995 red minimum tor Cooper 151 1979 and 2 a The t e years betWeen na see Section 2 t Arctic Perovich 52 a1 2007 The largest in creases in total yearly solar heatinput as much as 4 per year occurred in the Chukchi Sea and adjacent areas Perovich 52 a1 2007 The increase in latent heat has the potential to de lay ioe formation andor decrease seaioe ex tent Nihashi amp CavalieIi 2006 The trend in ecreased seaice extent throughout the year is further supportive ofincreased heat storage Serreze 52 a1 2007 The increase in heat may also increase the degree ofstrati cation reduce vertical circulation Aagaard amp Carmack 1989 restrict the availability of limiting nutrients to the upper ocean and reduce primary produc tion Smetacek amp Nicol 2005 Documented changes in ice dynamics in the Arctic illustrate the highly variable and com plex physical and chemical mechanisms and feedbacks that have potential to fund tally in uence the structure and function of polar ecosystems Watercolumn stability nutri ent availability trace element and macronutri ent ratios salt content heat content and solar a amen tractton ot tncorntng s tatton ts E gt rne local tormatton ana extento sea tce an sec tce coastal gtacters and tee a ater tncreases rne solar neattng ot rne u perpetuates sentoe rnelttng along tts margtns 4 tea snetves 5 Local otmosphettc fotctng serves to be of s elves teen Annals of he New York Academy of Sciences ntgn sentoe albedo O 8 Dtck 2003 rne matortty ts re ected back tnto rne atrnospnere Arr ng to tncrease rn g rates of n ts approxtmolely o 07 Dtck per ocean and Relattvely warrn ocean currents can ltrntt tntluence rne rnelttng rates of glacters ana allt up or consoltaate tce o Melttn ses tresn water tnto tne surface layer wntcii provtaes tncreasea verttcal stabtltty tn rne water column radiation have been reported to signi cantly ange in response to alterations in seaioe dynamics These environmental variables are fundamental drivers of primary production in polar regions including timing of growth 39 ribution diversity and fu yd 2002 Sakshaug 2004 These variables also establish whether production is primarily exported to the ben thos remineralized andor available to higher trophic levels Stein amp MacDonald 2004 For example high net production was found along a receding ice edge with lowlevel production in surrounding open ocean areas Owrid 52 a1 2000 The icebased food chain of the high Arctic in which energy is transferred from ice P biota to copepods and amphipods to polar cod to seals to polar bears will likely be impacted by shrinking seaice cover It is not clear how ever if the loss ofice will decrease the overall oceanic productivity or increase it Smetacek amp Nicol 1985 by the ampli ed effect on light eld Winther 52 a1 2004 It is therefore important to examine some ofthese broadscale patterns in primary producers in connection with cur rent changes in ice d namics This can serve as a useful preface for discussion of speci c cli mate impacm on different components within the ecosystem Seaice loss can be coupled with higher temperatures and increased primary produc tion This is particularly evident in the basins Molina et al Changes in Ice Dynamics and Polar Marine Ecosyslems 2007 Chlorophyll 60 Figure 5 A tem oral and spattal record of temperature The top panel ts the latttudtnal mean 65 N to 85 N ntghtttm tor the pertod of August 2006 through Augus panels are the latttudtnal mean 65 N to 85 N chlorophyll a mg August 2002 through August2007 as a tunotton ot longttude The bottom panel ts thespattal chlotop yH a mg m3 concenttottons t August 2007 Data are dertved ltom the OBPG MO dtstrtbutton ot the mean Therma es andd edtnt tss d Gm Us t 2007 g ru yw re ocqutted Ustng the GESrDlSC tnr Vtsuahzatton and Analysts tntrastruoture Gtovonn W 0 120 E and chlorophyll tor the Arotto e sea Sutloce Temperature cc as a tunotron ot longttu e The mrddle m4 oonoentrattons trom rom August 2002 through DlSrAquo monthly global 9km products ottve Onhne era t as part of the NASAs Goddard Earth Sctences tors Data and tntormanon Setvtces center Dtsc ln color tn Annas onltne adjacent to openings to lower latitude wa ters Serreze et a1 2007 Stroeve 52 a1 2007 Seasurface temperatures from August 2006 to August 2007 were signi cantly higher in the Chukchi Sea Davis Straits and Fram Straits showing the intrusion ofAtlantic water into the region Fig 5 In addition these locations ex perienced higher temperatures into the winter High concentrations of algal biomass are seen in the Beaufort Sea 120 W7180 VV along the eastern side ofGreenland in Baf n Bay 50 VV and particularly along the coastline of the Bar ents Kara and Laptev Seas 30 E7180 E The latitudinal mean concentrations do show dramatic interannual changes with the exoe tion ofthe region between 0 and 30 VV where the biomass appears to have increased over the 5year period Fig 5 The location of this in crease appears to be in the northern extent of 3 the Greenland Sea between Greenland and the Svalbard island group Fig 5 lower panel The highestintegrated biomass over the 5 years was evident along the coastlines of the Arc tic Ocean and one large area in the Barenm ea This is consistent with river runoff nu trient availability and increased stability along coastlines as well as the convergence of At an Arctic water in the Ba Sea Smetaoek amp Nicol 2005 Even though re gional differences may be di icult to discern at this scale there is an increasing trend in the amount of primary producer biomass in the Arctic Fig 6A This increase appears to be a northward latitudinal advance in biomass that occur north of 76 N and is not in uenced by the coastlines of the Barents Kara or Laptev Seas Fig 7 and is consistent with the doc umented retreat of the summer perennial ice Edtth Sctences GES Dom and thtmmgtm Setvtces Center Dtsc edge margins Druzhkov 52 a1 2001 Serreze 52 a1 2007 Examination of the period from August 2006 to August 2007 clearly shows the response of the phytoplankton biomass to the receding ice edge Fig 8 The advance of the bloom can be seen proceeding northward as a function of time at an approximate rate of 1 per month in the boreal summer 122 The Southern Ocean The trends in seaice cover in the Antarctic differ markedly from those in the Arctic as the Southern Ocean is isolated from land masses and the formation and extent ofsea ice is gov erned largely by oceanic processes In a stud from 1979 to 1998 Zwally and coworkers 1 Annals of he New York Academy of Sciences 2002 found an overall increasing trend in sea ice extent of approximately 1 per decade Similar estimates ofa 15 increase per decade con rm this trend Fichefet 52 a1 2003 Ducklow 52 a1 2007 The trends are not uniform across the Southern Ocean however There are in fact signi cant regional differences Ackley 52 a1 2003 Positive decadal trends in seaice extent were found for the Weddell Sea Paci c Ocean and Ross Sea sectors slightly negative in the Indian Ocean and strongly negative 10 in the BellingshauseniAmundsen Seas sector Zwally 52 a1 2002 Although the re gional de nitions varied an extension of the time series record from 1979 to 2002 yielded similar trends with pronounced increases in the Paci c sector and signi cant decreases in the Bellingshausenwestern Weddell sector Liu a a1 2004 Yuan 2004 Correlations with ice core records also suggest a decline in sea ice extent in the Indian sector Curran 52 a1 2003 Temporal changes in seaice extent in these sectors were positively correlated with the Antarctic Oscillation and negatively cor related with the El Ni oaSouthern Oscillation NSO however these correlations did not explain regional discrepancies in the magni e of seaice extent Liu 5 a1 2004 Yuan 2004 Stammerjohn 52 a1 2008 The signi cant decreases in the extent of sea ice docu mented along the Antarctic Peninsula also co incide with a signi cant warming trend in this area Chapman amp Walsh 1993 In fact the climate of the Antarctic Peninsula is chang ing more rapidly than any other region in the Southern Hemisphere Atmospheric tempera tures have increased nearly 3 C from 1951 to 2004 Vaughan 5 a1 2003 Meredith amp King 2005 Skvarca and colleagues 1998 docu mented the rst year with a mean annual air temperature above 0 C on the eastern side of the Antarctic Peninsula In addition to decreases in seaice extent in this region increased temperatures coin cide with signi cant changes in the activity of glaciers and ice shelves Eightyseven percentof 244 marine glacier fronts along the Antarctic rE Molina er al Changes in Ice Dynamics and Polar Marine Ecosyslems ngorgaxig i mi am In nz n3 IIA n5 n5 n1 I 25 m n I r 2007 2006 r 2005 2004 2003 68 N 72 76 80 84 N Figure 7 The dtttudtndt medn ohtorophyH o mg m4 oonoentrdttons as d tunotton of ttrne from August 2002 through August 2007 for the Arotto 65 N to 85 N The trndges and data used m thts stu y were doqutred Usmg t e rDtSC tnterdottve Onhne Vtsud dnd Andtysts tntrdstruoture Gtonnnt as part of the NASA s Godddrd Edrth Sctences GES Dam and tntormdnon Setvtces Center Dtsc tn cotor tn Annas onhne A J A B F o N D e o a 0 A saw 72 76quot 30 54m A B Chlorophyllamgm399 J us n2 n u as as 1 15 m an A 398 F o N D In 0 a 0 A 72 68 60 S Figure 8 The dtttudtndt medn ohtorophyH o mg m 3 oonoentrdttons as d tunotton otttrne from August 2006 through August 2007 for the A Arotto 65 N to 85 N and B Antdrotto 60 S to78 Arrows deptot the toodtton dnd ttrntng of the response of prtmdry producers to the retredtott e mdrgtndt me e ges e trndges and data used m thts study were dog Ustng the GESD SC tnterdottve Onhne Vtsuthdtton gnd Andtysts tntrdstruoture Gtonnnt ds pdrtot the NASA s Godddrd Edrth Sctences GES Data and tntormdtton Setvtces Center Dtsc tn sotor tn Annas onhne 5 CL 276 Peninsula have retreated between 1940 and 2001 with the boundary of receding glaciers moving progressively southward over that time period Cook et a 2005 A history of the ice shelves along the Antarctic Peninsula also doc umented a southerly retreat over the same pe riod Skvarca et a 1999 In fact the Larson Ice Shelf is steadily decreasing in size and it experienced dramatic collapses in l995 Skvarca et a1 1999 and 2002 Fig 3B The cause of the breakup of the Larson Ice Shelf has been shown to be a combination oflong term thinning by a few tens of meters over thousands of years and shortterm cumulative increases in surface air temperature that have exceeded the natural variation of regional cli mate over the last 10000 years Domack et a1 2005 Instability in regional ice shelves has also been linked to intrusions of upper Cir cumpolar Deep Water CDVV onto the con tinental shelf Smith et a1 2007 Intrusion of the warmer CDW has also been suggested as a mechanism for the observed retreat of glaciers and increases in air temperature in the region Cook et a1 2005 Vaughan and colleagues 2003 suggested changing oceanographic cir culation as a mechanism to explain the rapid re gional warming in the area Meredith andKing 2005 reported coincident changes in surface waters along the Antarctic Peninsula with sur face temperatures in summer rising more than 1 C and upper layers exhibiting strong salini cation This increase was found to be driven by atmospheric warming and reduced rates of seaice production Perovich et a1 2007 which may contribute signi cantly to the continued climate change in the region Meredith amp King 2005 Overpeck et a1 2006 Loss of sea ice in this region will likely decrease strati cation via these positive feedbacks Conversely increased freshwater input from melting glaciers and ice shelves will act to increase strati cation along the coastal margins Although comprehensive analyses of strati cation are not available for this region the interplay between these pro cesses in the context of regional warming is likely to increase spatial heterogeneity in the Annals of the New York Academy of Sciences physical and chemical environments Ecosys tem responses to these shifts will likely mimic their spatial and temporal complexity The warming trend along the Antarctic Peninsula is clear in seasurface temperature data from August 2006 to August 2007 Fig 9 This area of warm water extends across the Bellingshausen Sea and well into the Amund sen Sea These data also show that the arrival of warm water occurs early in the austral spring September October Additional warming is evident in the Ross Sea though it is unclear whether this pattern is unique for this year It is interesting to note howeven the longitudi nal extent of positive temperatures for much of the austral winter The chlorophyll a concentra tions along the Antarctic Peninsula appear to be increasing with a propagation of high biomass to the west F ig 9 This westward propagation is also evident in the Amundsen Sea 1 10 VV and off the Getz Ice Shelf 170 VV Whether these apparent shifts in biomass are part of longerterm oscillations Liu et a1 2004 Stam merjohn et a 2008 is unclear Comparison of longitudinal biomass between 2003 and 2007 also indicates a trend from distinct bloom lo cations in 2003 to more heterogeneous dis tribution around most of the continent in the later years As in the Arctic the total monthly chlorophyll 1 concentrations for this de ned re gion have increased in the 5year period Fig 6B The increased concentration appears to be trended northward Fig 10 howeven neither seaice extent nor anomalies in sea ice appear to be related data not shown The annual re treat of the ice edge and associated bloom is clear from 2006 to 2007 with the rate of re treat similar to that in the Arctic Fig 8 What is apparent from the temporal record of latitu dinal change is an increase in chlorophyll a in the higher latitudes ofthe Southern Ocean Fig 10 This suggests the ice edge around the conti nental shelfhas been receding further south and there has been a signi cant impact from melt ing ofcoastal glaciers and ice shelves Cook et a 2005 on the accumulation of phytoplankton biomass Molina el al Changes in Ice Dynamics and Polar Marine Ecosyslems 277 W 120 50quot 0 60 120 E Figure 9 Same as Figure 5 except tor the Anmmns sous m 78 S ln color m Annas nlme J Chloroahill a SIDE mi nm m M n3 n1 n5 M M 1 2 m an 2007 2006 2005 2004 2003 7e s 72 55 54 eo s Figure 10 Same as nge7 excepltor lheAnmrcnc sous m 78 S ln color m Annas onlme These recent largescale patterns in prima lite data provide a View of only the surface dy producers from both poles appear consistent namics and they do not correlate directly with with the existingliterature on climatemediated primary production in these re 39ons Behren changes in ice dynamics Although these satel feld amp Falkowski 1997 Behrenfeld a a1 20057 278 they show signi cant changes occurring over large spatial and temporal scales Any alteration in primary production is likely to in uence the rates of biogeochemical cycling oceani atmosphere gas exchange and the viability and success of higher trophic levels Examination of the latter in the conteXt of climate variability re quires an ecological framework that addresses the response of biological systems at all levels of organization across relevant temporal and spatial scales 723 Direcf and Indirecf Impacfs of Ice Dynamics on Polar Ecosysfems Declines in sea ice may have either direct or indirect impacts on ecosystem components Many species use sea ice as a substrate or es sential habitat to successfully complete their life histories Hop et a1 2002 The docu mented loss of sea ice in polar regions has had direct impacts on these species and de pendentassociated species The potential for direct impacts of seaice loss begins at the base of the food web where signi cant numbers of obligate lowtemperature shadeadapted algal species Lovejoy et a1 2006 2007 and radi olarian species endemic to the Arctic Ocean Basin have been found Lovejoy et a1 2007 The timing and rate ofseaice loss has also been found to directly determine the degree of phys iological stress in ice algae Ralph et a1 2007 and is related to mortality in zooplankton Hop et a 2002 These physiological stressors have been linked to the nutritional status of ice algae Palmisano amp Sullivan 1982 with implications for higher trophic levels Sea ice also serves as habitat for invertebrates such as Antarctic krill Murphy et a 2007 andArctic amphipods Macnaughton eta 2007 seabirds such as pen guins Forcada et a1 2006 and marine mam mals such as Antarctic fur seals minke whales crabeater seals Ribic et a1 1991 and harp and hooded seals Johnston et a1 2005 Friedlaender et a1 2007 Direct impacts of habitat loss can be con trasted with indirect changes that result from altered hydrography For example shifts in hy Annals of the New York Academy of Sciences drography have been linked to decreased sea ice observed in both polar regions and al tered hydrography provides a mechanism for introducing species Reintroduction of Myt m edulis has occurred along the west coast of Svalbard with the northward movement of North Atlantic Water Berge et a1 2005 2006 Blake 2006 Invasion of Paci c water into Chukchi Sea IiuXin et a1 2005 and Fram Strait Shimada et a1 2004 has introduced a host of invertebrates to the Arctic basin that can sustain their reproductive cycles and overwin ter because of the regional shift in hydrogra phy and climate Sirenko et a 2006 The in creased ow of rivers into the Arctic Ocean has been shown to decrease benthic diversity because of increased siltation and to halt feed ing of Arctic cod and sand lance larvae due to increased plume depths Fortier et a1 1996 In Antarctica the intrusion of CDW into the shelfwaters has been linked to seaice declines iceshelf disintegration and glacial recession These warm waters may introduce and select for different trophic assemblages Atkinson et a 2004 which may eXplain longterm trends in breeding for birds and mammals in the re gion Barbraud amp Weimerskirch 2001 2006 Rutishauser et a1 2004 Forcada et a 2006 In fact Biuw and coworkers 2007 documented a tight link between feeding and particular wa termass types in Southern elephantseals These water masses are partially dependent on seaice dynamics with potential consequences for prey abundance and distribution and energetics of higher trophic levels 724 Framework for Evalua ng Ecosysfem Change Polar regions are characterized by a rela tively short photic period and signi cant spa tial variations in productivity These constraints force organisms to meet the bulk of their en ergetic requirements in speci c places within a narrow time window Climatic changes are disrupting otherwise tight trophic interactions between predators and prey and these dis ruptions can be both spatially and temporally Molina et ul Changes in Ice Dynamics and Polar Marine Ecosystems dependent The concept of synchronicity in food requirement and food availability and the subsequent impacts on energetics sur vival and reproduction has been cast in the matchimismatch hypothesis Cushing 1969 1982 1990 The hypothesis was rst developed to explain recruitment variation in a popula tion by relating its phenology with that of prey species The example used by Cushing 1969 was to examine how variability in the timing of peak production of zooplankton prey leads to variation in mortality of larval shes and yearclass recruitment Although many vari ables are interacting to determine recruitment or breeding success of an individual or popu lation the application of the matchimismatch hypothesis in the polar regions is appropriate Barbraud amp Weimerskirch 2006 Durant and colleagues 2007 advocate that two important requirements must be met in order to consider the matchimismatch hypothesis The rst is that both predators and prey must display a high degree of seasonality The second is that the recruitment or survival of predators is gov erned by bottomup control Although strong seasonality is well established for polar organ isms debate about bottomup controls contin ues Smetacek amp Nicol 2005 In general food availability is rarely the only factor governing survival and reproductive success but it is ac cepted as a major driver in marine ecosystems Oro et a1 2004 A number of alternative hypotheses have been proposed in the literature to explain the impact of the physical environment on the predatoriprey interactions The mem bervagrant hypothesis underlines the role of displacement of eggs and or larvae from fa vorable shelf or bank areas Sinclair 1988 Sinclair amp Iles 1989 The migration trian gle hypothesis describes how organisms must migrate between spatially separate adult feed ing grounds spawning grounds and nursery areas HardenJones 1968 Although initially applied to sheries the bene ts from migra tion could apply to many organisms or popu lations Oro et a1 2004 More recently the hy 279 drographic containment hypothesis combined the principles of the matchimismatch and mi gration triangle hypotheses Cushing 1995 The oscillating control hypothesis Hunt et a1 2002 attempts to relate the temporal dynam ics of sea ice and variations in temperature at high latitudes over decadal scales to al terations in topdown and bottomup control of piscivorous shes All of these hypotheses are distinct and speci c to particular physical drivers but they are arguably related to the de gree separation of between predator and prey which is the foundation of the matchimismatch hypothesis Initially the basic premise of the matchi mismatch hypothesis focused on temporal vari ability howeven factors in uencing energetics survival and reproductive success are equally dependent on the degree of spatial overlap For example seabirds are known to concentrate their foraging in oceanic fronts at water masses boundaries ice edges and currents which act to concentrate prey see sections 212 223 and 31 1 Hunt 1990 Schneider 1990 Ifthese physical features are weak or the distance to concentrated prey is increased the effective de gree of spatial overlap relative the prey eld decreases and can be equated to a temporal mismatch Kooyman et a1 2007 For seabirds and marine mammals one must also add depth to the spatial consideration As an example telemetry studies showed that King Penguins Mptenacfytespatagam39ca exploit prey concentrated at the thermocline of the polar front located 3407450 km to the south of their breeding site Charrassin amp Bost 2001 Increased distance to the polar front andor a deeper thermo cline would translate to mismatch with nega tive impact on the penguins reproductive suc cess In the Arctic Hassol 2004 highlights the increased energetic costs suffered by walruses as a function of retreating ice edges Colonies are xed in space along coastlines so the dis tance and depth of productive areas increase as the ice edge progressively retreats north in response to climate change The increased for aging time also in uenced the health of pups 280 In pelagic systems spatial overlap itself be comes more critical for organisms that occupy higher trophic levels This is a result ofa com bination ofdecreasing scale of organization or increasing spatial variance Horne amp Schnei der 1995 as well as a change in encounter rate probabilities between predator and prey Sims 2006 Benthic systems have also been shown to be changing community structure and production with decreases in seaice cover McMinn et a1 2004 As these systems are spa tially xed with respect to depth any changes in the overlying water column including sea ice will lead to increased predatoriprey mis matches In the Northern Bering Sea such a mismatch can be discerned from geographic displacement of marine mammal populations coinciding with a reduction in benthic prey an increase in pelagic sh a reduction in sea ice and an increase in air and ocean tempera tures Grebmeier et a1 2006 These ecosystem changes in the shallow Bering Sea may serve as a model for shallow shelf systems in the Arctic Ocean Thus a compleX rubric of temporal and spatial overlaps establishes the upper limits of matching and predatoriprey interaction While speci c predatoriprey interactions are governed by this temporal and spatial depen dency from an ecosystemlevel perspective overall productivity will be determined by the interactions among matches and mismatches at all trophic levels van Franeker et a1 2001 Additionally in pelagic ecosystems algaei zooplankton interactions form the basis for en ergy uX to higher trophic levels The recruit ment success of higher trophic levels is highly dependent on synchronization with pulsed planktonic production Edwards amp Richard son 2004 A decoupling of predatoriprey re lationships at lower trophic levels due to for example climate change will likely lower pro duction for all higher trophic levels with poten tially drastic ecological consequences Winder amp Schindler 2004 Edwards and Richard son 2004 documented such climateinduced Annals of the New York Academy of Sciences changes in the North Sea where mismatches increased as the synchrony of peak produc tion among successive trophic levels began to decay Other considerations can mediate the im pacts of temporal and spatial mismatches among trophic levels For example Durant and colleagues 2005 found that overall food abun dance could offset timing mismatches Offsets may also be moderated by food quality ie taX onomic composition and condition ofthe food source The plasticity ofan organism ie feed ing generalist or population is also likely to off set time and space mismatches Walther and co workers 2002 discuss the thermal tolerances of Antarctic organisms and the decreasing likeli hood that some organisms will be eXposed to their lower thermal limits because ofincreasing temperatures This will thereby allow increases in both numbers and eXtent of these popula tions previously at the edge of their ran ge while also increasing the risk of eXposure to upper thermal limits for some organisms Some plas ticity is afforded to mobile species as they are more likely to behaviorally respond to change Plasticity is also increased in mammals as they accumulate body reserves in preparation for winter and transfer to young which creates a temporary buffer allowing for migration to improved habitam Howeven postweaning sur vival for placecentered foragers such as pin nipeds still will be highly dependent on proxim ity offood resources to the rookery Rutishauser et a1 2004 Some populations are also depen dent on genetic variability and age structure If the timing of a trophic mismatch disproportion ately affects these characteristics of a popula tion the probability of a total yearclass failure is likely to increase This was shown in cohorts of Arctic cod in response to climatedependent changes in temperature and prey density Cian nelli et a1 2007 Ottersen and colleagues 2006 highlight this general concern for commer cially eXploited sheries which receive spe cial selective pressures Ecological changes in turn reshaped the sheries contributing Molina et al Changes in Ice Dynamics and Polar Marine Ecosystems to altered distributions of sheriesdependent communities Hamilton amp Haedrich 1999 making it dif cult to discriminate between the effecm of harvesting and ecosystem impacts driven by climate change Smetacek amp Nicol 2005 The matchimismatch hypothesis also ap plies only to predatoriprey interactions that respond to different environmental cues for their phenology The plasticity of an organism therefore decreases if the environmental cue ie photoperiod is invariable for particular latitudes In the Arctic marine environment the phytoplankton bloom along the marginal sea ice can occur early or late depending on seaice dynamics Zooplankton is spatially cou pled to phytoplankton and metabolically af fected by sea temperature leading to oscillating controls where the system alternates between primarily bottomup control in cold regimes and primarily topdown control in warm regimes Hunt et a1 2002 In the same con text the rate and spatial eXtent of seaice retreat is likely to drive sh productivity and to some eXtent productivity of piscivorous shes Cian nelli amp Bailey 2005 marine birds Croxall et a1 2002 and mammals Grebmeier et a1 2006 Given these predatoriprey dependencies it is clear that climatic forcing will impose change in polar ecosystems If some species are cou pled to an invariant environmental cue such as photoperiod and other species have adapted their phenology to current climate condi tions then climate change can be eXpected to weaken the synchronization match between food availability and the food requirements for the average predator individual Visser et a1 2004 This introduction has provided background on ice dynamics the mechanistic drivers for the observed changes in climate and ice dynamics and an ecological framework for ecosystem in teraction The following case examples high light and detail the current impacts of climate driven changes in ice dynamics on ecosystems They are divided into cases of direct impacts of seaice loss on polar organisms and interac 281 tions and cases of impacts related to indirect climateinduced changes 2 Direct Impacts of Decreasing Ice Habitat 21 The Arctic Ocean 2 7 7 Sympagic Fauna of the Arctic Food Web Historically a broken layer of sea ice capped 4717 X 106 km2 of the Arctic Ocean Fig 1 Sea ice comprises a threedimensional matriX of ice crystals and brine channels that does not remain static Leads and polynyas form and shift Specialized ora and fauna the sympagic assemblage occupy the brine channels in sea ice with edge habitats being particularly pro ductive Gradinger 1995 Overall the sympa gic assemblage plays a critical role in the pro duction and transfer of organic matter through Arctic food webs especially in areas where sea sonal sea ice reduces the penetration of light resulting in relatively low pelagic productivity Carmack et a1 2006 In fact sympagic or ganisms are central components of Arctic food webs and support many of the apeX predators found in the Arctic Fig l l Tynan amp DeMaster 1997 Hop et a 2002 Gradinger et a1 2004 Tremblay et a1 2006 Thus spatiotemporal patterns in the sympagic assemblage link the health of Arctic ecosystems to sea ice and its dynamics Warming of the earth s atmosphere changes the eXtent of sea ice and its dynamics Such changes represent critical forcing factors for Arctic ecosystems Less sea ice translates directly into loss of habitat for sympagic or ganisms The effects of altered dynamics may exacerbate the effects of habitat loss In par ticulan a mismatch between the life histories of key players in the sympagic assemblage and the dynamics of sea ice may yield undesirable consequences Flora and fauna with strong ties to sympagic habitats include ice algae amphipods cope pods hyperiids polar cod and ringed seals mam Wm mum Annals of the New York Academy of Sciences ure n DeplollonsolAtcllcloodwebltom A theSvalbard region odopledltom Hopecl 2002 F39s and B lrom the North W p ytoplankton as notal isotopes gutcontents and preVious literature Arctic ice algae comprise at least 40 taxa even in winter Booth amp Horner 1997 Werner 52 a1 2007 Although ice algae represent a relatively diverse assemblage diatoms contribute signi cantly to diversity and abundance Werner 52 a1 2 0 Key taxa include Meloxzm anma Alzheya bumm Amphipods s 3 am mam wzlkzzzku and Apharuxaglamalzx character ize sea ice throughout the Arctic Carey 1985 Lianne amp Gulliksen 1991a 1991b Poltermann 52 a1 2000 Werner amp Gradinger 2002 Arndt amp Beuchel 2006 These species grow to be 5 mm in length over a period of up to 6 years and mature in 172 years They pri marily occupy the interface between the seaice and the water column Pelagic zooplankton such as Pxeuabmlanu sp Calamity etbuteux and Calmuxglamah Gradinger amp Bluhm 2004 can be found in the water column beneath sea ice Calamity etbumt is the largest species at 5 mm in length Multipleyear life cycles char Pu ater Polynya system adapted lrom lremblay eta 2006 highlighted in bold gray to illustrate the importance ol ice tot e loo are ice algae Both lood webs were generated based on carbon budgets stable Sympoglc organisms are websltuclute Dotted lines are around acterize these species The hyperiid amphipod Themmu Zlbellula formerly Pam wmmu 121731174141 ranges throughout the Arctic Oce n These pelagic amphipods have life spans of 273 years and grow to 31 mm in length Koszteyn 52 a1 1995 Bumgadu maid the Arctic cod repre sents the most northerly distributed species of Gadidae and is a key species between lower and upper trophic levels in Arctic food webs Fig 11 Gradinger amp Bluhm 2004 It oc curs nearshore and offshore between 60 N and the North Pole Ringed seals tha hzxpw39a are abundant throughout the Arctic Ocean year round Weslawski 52 a1 1994 Born it al 2004 Environmental forcing factors in the Arctic undergo strong seasonal uctuations Werner 52 a1 2007 Starting in spring increased so lar radiation drives 4amp50 C increases in air temperature decreases in snow cover and thin ning of sea ice Increased solar radia creased snow cover and thinner sea ice result in more light impacting the sea iceiseawater Molina et ul Changes in Ice Dynamics and Polar Marine Ecosystems interface In addition increased seaice temper ature leads to lower brine salinity and greater brine volume The temperature of sea ice and the salinity of brine channels restrict diatoms to the lower decimeters of the seaice matrix Gradinger 1995 Increases in seaice temper ature and the presence of more lower salin ity brine expand suitable habitat for sympa gic ora and fauna Most importantly changes in light drive increases in the productivity and biomass ofice algae Gradinger 1995 Ice a1 gae have adapted to the low light levels char acteristic of sea ice and they begin growing at 2710 umol m 2 s71 By summer abundances of algal cells increase by one to two orders of magnitude to yield 17100 mg chlorophyll a m 2 A variety of primary consumers in habit or utilize the highly productive interface between the lower layers of sea ice and the water column Gradinger 1995 The endemic amphipods Onm39mus spp Gammams wilkitzkii and Apherusa glau39alis which live on the under surface of the sea ice and pelagic copepods that migrate to this interface feed on ice algae and each other Arndt 2002 Prokopowicz amp Fortier 2002 Gradinger amp Bluhm 2004 Arndt amp Beuchel 2006 Gammaridean amphipods reach abundances of 171000 animals m z and epipelagic copepods reach abundances of 500079000 animals m 8 Auel amp Hagen 2002 Gradinger amp Bluhm 2004 The hyperiid amphipod Themistu Zibellula and the Arctic cod Bamgadus saida represent key secondary consumers in habitats charac terized by sea ice As adults Themisto libeli Zulu appear to feed primarily or exclusively on calanoid copepods especially Calanus lyi perbareus and Calanus glacialis Scott et a1 1999 Auel amp Werner 2003 This hyperiid amphi pod exhibits direct development with breeding in spring and summer Auel amp Werner 2003 Bareugadus saida associate with sea ice from their larval stage through their juvenile stages and they can be found sheltering in brine channels Gradinger amp Bluhm 2004 Spring and sum mer cohorts oflarvae have been recorded and larval survival bears a complex relationship to 283 water temperature as effected by the breakup of sea ice and production of copepod nauplii in response to spring algal blooms Drolet et a1 1991 Fortier et a1 1995 Michaud et a 1996 Fortier et a 2006 Large schools of adults move through the Arctic Ocean Welch et a1 1993 Gradinger amp Bluhm 2004 and dense swarms of Themistu Zibellula can account for over 20 of the energy content of the macrozooplank ton community Percy amp Fife 1985 Auel et a1 2002 Gradinger amp Bluhm 2004 Both Bum agadus saida and Themistu libellula exert signi cant predation pressure on the amphipods and copepods that graze on ice algae In summer larger copepods found under sea ice migrate upward to the chlorophyllrich interface be tween the sea ice and the water column during the period of maximum decrease in irradiance and return to depth well before the maximum increase in irradiance associated with dawn Fortier et a1 2001 This normal diel vertical migration occurs despite the lack of a gradient in ultraviolet B radiation or temperature and it has been interpreted as a reaction to visual pre dation by Themisto Zibellula and Bareugadus saida Fortier et a 2001 Ringed seals Phaca hispida appear to be generalists but Bareugadus saida and Themisto libellula rank among the top ve prey items VVelch et a 1993 Weslawski et a1 1994 Gradinger amp Bluhm 2004 The seals primarily feed on prey less than 20 cm in length which encompasses the bulk of the size distribution for Bareugadus saida and Themisto Zibellula W eslawski et a 1994 In fact Phuca hispida near sea ice appeared to remain in relatively shallow water because of the distribution of these prey species Born et a1 2004 In concert with a warming of the ocean the extent ofthe sea ice in the Arctic has decreased by an average of3 per decade between 1978 and 1996 and the ice has thinned by up to 40 since 1950 Parkinson 2002b Predictions enhanced with data from a major reduction in sea ice observed during 2002 estimate 127 46 decreases in seaice extent by 2100 and essentially icefree summers by 2099 Walsh amp Timlin 2003 Overpeck et a 2006 The 284 rami cations of such changes in sea ice may reach to upper trophic levels Changes to sea ice especially a decrease in its extent are highly likely to lead to changes in the distribution and abundance of sympagic ora and fauna In essence the sympagic portion of the Arctic ecosystem should shift toward a pelagic sub arctic ecosystem Grebmeier et a 2006 Phy toplankton productivity is predicted to increase as light allows utilization of available nutrients Smetacek amp Nicol 2005 As a result meso zooplankton productivity should also increase with eXisting Arctic species meeting increasing competition from subarctic species that are eX panding their range Gradinger 1995 For eX ample numbers of Thean libellula and Barge agadus saida may decrease due to their use of sea ice during early lifehistory stages and be cause of increased competition with subarctic species such as Themistu abysmmm and Gadus marhuaj that will eXpand or continue to eXpand their ranges northward Gradinger 1995 Auel et a1 2002 Drinkwater 2005 Phuca hispida may not be able to adapt to a loss of habitat espe cially a habitat used for birth lairs combined with a reduction in its principal prey including Bareugadus saida and Themisto libellula Tynan amp DeMaster 1997 Less certainty surrounds the effects of altered seaice dynamics Temporal shifts in the eXpan sion and reduction of sea ice may lead to mis matches with the life histories of key sympagic organisms These links include the timing of increased activity and reproduction of primary and secondary consumers in anticipation ofin creasedproductivity of ice algae If one or more of the links between increased light penetra tion higher production by ice algae increased activity and breeding of crustacean grazers and predators and production and feeding of lar val and juvenile Bareugadus saida fail then effects may ow through the sympagic assemblage and on to top predators such as Piwca hispida vari ous bird species see section 212 and perhaps polar bears Urqu maritimus see section 213 Thus the sympagic assemblage represents a central component of the Arctic ecosystem that Annals of the New York Academy of Sciences is closely tied to the eXtent and dynamics of sea ice The ability of the sympagic assemblage to cope with habitat loss increased competition and altered habitat dynamics remains a central and uncertain element in predictions of effects owing from changes in sea ice due to warming ofthe earth s atmosphere Tynan amp DeMaster 1997 272 Impacfs of Arc c Seaice Loss on the Black Guillemof As stated in the previous section the oating sea ice in the Arctic Ocean supports a sym pagic underice community with iceadapted amphipods and a single sh species Arctic Cod Bureagadus sandal particularly important to marine apeX predators throughout the Arctic Basin LDHHC amp Gulliksen 1989 This commu nity provides a nearsurface food source that is especially important in the high Arctic where limited miXing limits water column productiv ity and prey In the western Arctic including the Chukchi Beaufort and East Siberian Sea the sympagic community is important to res ident marine mammals Hoekstra et a 2002 and migrant and resident bird populations Di voky 1976 1984 Watson amp Divoky 1972 The summer melt of the Arctic sea ice has dramatically increased in recent decades with the 2007 pack ice minimum eXtent only about 50 of that in the 1960s and l970s Fig 2 Western Arctic waters eXperienced some of the earliest and most eXtreme decreases in ice eX tent Fig 3A Comiso 2002a 2002b Maslanik et a1 1996 The reductions in seaice eXtent could be eXpected to cause concurrent changes in the availability and abundance of sympagic prey to the region s trophic webs but the con sequences of these changes have been poorly documented due to a lack of systematic obser vations Annual observations of the black guillemots Cepphus gvylle breeding on Cooper Island in the western Beaufort Sea 30 km east of Point Barrow Fig 3A provide some indica tion of how the recent ice decrease has af fected marine apeX predators The race of black Molina el al Changes in Ice Dynamics and Polar Marine Ecosyslems guillemot occupying the western Arctic is ap parently one of the few avian species that is a seaice obli ate in the Arctic It breeds north of the Bering Strait at locations where nearshore sea ice is present for at least part of the breeding season with the largest colonies in regions where ice remains near shore throughout the summer Portenko Kondratyev 52 a1 2000 While lower latitude conspeci cs and congeners rely in large part on nearshore demersal prey during breeding f there is limited diversity and abundance o nearshore prey in the Arctic due to ice scour Gutt 2001 and the zooplankton and sh associated with the underside of ice provide guillemots with an alternative to nearshore demersal prey The effecm ofthis change in prey availability on the marine trophic webs in the region could be expected to be major One of the data sem that allow examination ofthese ef fects has been gathered at Cooper Island where annual observations of black guillemot breed ing biology have been made since 197 TL 1 l s L s s s u ulation size breeding success and prey pro vided to nestlings The Cooper Island colony where all nests are in manmade structures had 10pairs when it was discovered in 1972 Divoky 52 a1 1974 but nestsite creation increased the colony to 200 pairs in the late 1980s Fig 12 when there was a population of gt100 non breeders and the population was nestsite lim ited Beginning in the early 1990s however the colony began to decline decreasing to as low as 115 pairs in 1998 and 1999 before recover ing slightly in the 21st century The decline in population coincided with a shift in the Arctic Oscillation the dominant atmospheric circula tion pattern in the western Arctic that resulted 39 ent and rapidly increasing melt Maslanik 52 a1 1996 Comiso 2002b Rigor 52 a1 2002 The speci c causes for the decline are being investigated but could in clude decreased breedingproductivity at source colonies changes in recruitment as summer dis ribution of nonbreeders was modi ed by ice seaice movem 50 gt 1975 1980 1985 1990 1995 ZDOD 2005 Year Figure 12 Number of black guillemol neslsiles and breeding pairs 197572004 Dashed vemml lme Show beginning of quotwarmquot phase Am Oscillation and increased summer me me retreat and decreased breeding productivity at the study colony The effecm ofseaice retreat at the colony were seen as breeding productivity dropped as the distance from the island to the ice quot 39 quot Fig 13 Daily observations ofblack quot39 in 2007 showed a high correlation between the percentage of Arctic Cod in the diet and the distance to the ice edge Fig 14 This is evidence for spatial mismatch and the breeding success ofthe black guillemot being directly linked to the accessibility of the seaice edge speci cally to the availability ofthe Arctic Cod While the ice retreat has decreased prey abundance for seabird species dependent on sympagic prey it is concomitantly allowing more subarctic species to expand their ranges northward with the horned pu in prospect ing nest sites in the 1970s Divoky 1982 and breeding at the Cooper Island in 1986 the rst breeding record ofthe species in northern 213 Ice Loss and Population Trends in Polar Bears andAssociated Species Perhaps the most dramatic impact ofseaice loss on an upper trophic predator is the exam ple ofpolar bears Urm mmzmux Polar bears depend on sea ice for many aspects of their 286 Annals of he New York Academy of Sciences A 1 B 1 2007 7 use u 539 39 u g 3150 gus g m 31007 7 5w E I s E E 39 c In u D u n sa 39 02 u l 39 39 l l l l I 1571 1980 1990 2101 2111a 1970 1950 1991 man 21110 Year Year Fi ure 13 A snafu Distance to ice edge km from black guillemot colonies on Cooper lslnnd b g breeding success 01 lack Mllemols on Cooper ism owning years W111 minor nest pred lllon 197572004 life history Stirling amp Derocher 1993 Most importan y the polar bear requires sea ice to feed it hunts ringed P7147541 71251724121 and bearded seals Erma mx barium as well as other i associated marine mammals such as walrus beluga whale or harp seals by lying in wait at breathing holes in the ice by stalking their prey on ice oes or by leaping on snowcovered seal birth lairs eg Martin amp Jonkel 1983 Hammill amp Smith 1991 Sea ice can also be a latform on which polar bears seek out mates and copulate Ramsay amp Stirling 1986 and w 39 h they traverse long migratory routes Schweinsburg amp Lee 1982 It is a drifting means of reaching maternity denning sites on land Harington 1968 and can serve as a den ning site itself Lentfer 1975 Amstrup 1986 Deteriorating and retreating seaice condi tions have been linked to decreased natality decreased body condition altered behaviors increasing numbers of negative interactions wit humans and mortality in the polar bear Stirling amp Derocher 1993 Amstrup amp Gard ner 1994 Stirling Hal 1999 Regehr Hal 2005 Fischbach a a1 2007 Declines in the duration of seasonal sea ice have been linked to declines in body condi t1 n of bears and subsequent population de clines FIG 15 With the early breakup of sea ice polar bears have less time to hunt in l quotD O O 539 g08 I u 2 lt1 gt 205 a 04 7 2 n I I l o m 1 1 21 km l 100 Distance to Ice igure e cent Arena cod of dmly prey for block gmllemov nesvlmgs m relanon to distance from sea ice in 2007 for food before some populations need to be gin the period when they fast Polar bears in western Hudson Bay and James Bay fast for at least 4 icefree months of the year Stirling amp Derocher 1993 and pregnant females for 8 months Stirling 52 a1 1977 Ramsay amp Stir ling 1988 Leaner females produce smaller lit ters and lighter cubs Derocher amp Stirling 1994 that are less likely to survive Derocher amp Stir lin 1996 Obbard 52 a1 2007 Stirling and colleagues 1999 found that body condition Molina et al Changes in Ice Dynamics and Polar Marine Ecosyslems 9 Mn Pole Emulfon 52 Figure 15 Numbers ndmnte lacunons of dew mented and mted effects of eclmmg set we on For A decrease 005 31ncrensmg mcmmw Smlmg ampDerocher1993 A Mormlny Ufor o nppmentsu Rode e 0 2007 6 SMng to landed dens n northern Atst Eschbach eml 2007 7 Sluftmg to landed dens n the Beaufort Sea populdnon Amr strup amp Gardner 994 8 Pregnant females expe g balm Bergen 007 9 Norm Sea populdnon 5 stable Smlmg mi 2007 0 Declmes n body condmon but no numbers n sou em H0 son Bay Obbmd eml 2007 1 Declmes n reproductwe success negotwely correlated wnb the Arctm Osmlld Mon 7 Svalbard Derocher 2005 de ned as weighUlengthY ofbears in western Hudson Bay from 198171998 declined with the earlier breakup of sea ice In 1991 however when seaice breakup occurred 3 weeks later due to cooling from the Mt Pinatubo eruption body condition improved and in the follo ing year female natality and cub survival were greater Stirling amp Lunn 1997 Stirling 52 al 287 1999 Between 1987 and 2004 this popula tion has declined by 22 Regehr 52 a1 2005 which islikely the result ofdeclinesin body 0on 39tion A similar pattern has been found in the Southern Beaufort Sea From 198272006 the mber ofyearlings per female there was pos itively related to the percent of days in which sea ice covered the continental shelf Cub size and apparent survival were lower with poor ice coverage Rode 324112007 Likewise a study in Svalbard Norway from 198872002 found that litter production rate natality and the body length of adulm declined over the period De rocher 2005 The reduced reproductive suc ss was correlated with the Arctic Oscillation index warmer years saw fewer cubs With increases in the period of open wa ter in western Hudson Bay polar bear interac tions with humans have increasediin par 39 lar more bears have been found in the town of Churchill and its dump Stirling amp Derocher 1993 Polar bears are also forced to swim longer distances back to shore In 2004 the ice edge north ofAlaska reached a record distance from shoreiover 250 km Stroeve 52 a1 2005 An unprecedented number ofpolar bears were seen swimming in open water gt2 km from shore that year including four that apparently drowned during a storm Monnett amp Gleason 2006 Sea conditions are predicted to worsen without sea ice dampening the effect of wind Monnett amp Gleason 2006 Polar bears prefer to feed at nearshore zones where ice is constantly moving opening and closing rather than pelagic areas Smith amp Stirlin 1975 Pomeroy 1997 Stirling 1997 Durner 52 a1 2007 Loss of sea ice typically translates to loss ofpreferred polar bear habitat because the spatial pattern of melt is gener ally from the edge of the ice pack polewards Durner at al 2007 Alaskan and Eurasian bears will either have to migrate long distances to remain on the ice or spend summers stranded on land Durner 52 a1 2007 With declines in sea ice polar bears are changing the habitat where they build mater nity dens Pregnant females create maternity cu 288 dens in autumn or early winterion land or iceiwhere they give birth and nurture the young until spring Amstrup amp Gardner 1994 In northern Alaska a 20year study of satellite collared females revealed signi cant changes away from dens on pack ice in favor of dens that are landbased Fischbach et a1 2007 The longer melt period and the replacement of sta ble old ice with youngen unstable oes was likely responsible for this pattern Furthermore a 198171991 study in the Beaufort Sea popu lation found that in later years a higher propor tion of the bears made landbased dens Am strup amp Gardner 1994 No differences were observed in the success of these dens but this trend toward denning on land is a matter of concern for two reasons I landed dens are more susceptible to human disturbances Am strup 1993 and 2 if ice breakup trends con tinue foraging females may not be able to re turn to land before their route is cut off forcing them to den on suboptimal ice Fischbach et a1 2007 Bergen and colleagues 2007 used the pas sive microwave record of sea ice from 19797 2006 to estimate that polar bears returning to Alaska to den have eXperienced an annual in crease in minimum travel of 678 km per year gt168 km over the 28year period This rate almost doubled after 1992 They predicted the iceretreat rate based on global climate models to be 16 kmyear over the period 200172060 which would mean an increase in the distance pregnantfemales travel from 385 km in 1985 to 1487 km in 2060 It would take a bear 10 and 38 days respectively to travel these distances Bergen et a1 2007 While polar bears have some plasticity in their diets they would have dif culty surviv ing on purely terrestrial resources There are increasing reports of bears searching for food on land eg Stempniewicz 1993 2006 which may be due to the fact that bears are looking for alternative prey Derocher and coworkers 2000 observed bears hunting and scavenging reindeer Russell 1975 reported that bears in James Bay eat birds marine algae grasses and Annals of the New York Academy of Sciences berries Howeven the bulk oftheir diet is made up of marine mammals that are associated with ice as reviewed in Derocher et a1 2002 Polar bear distribution is circumpolar but the direct effects of loss of sea ice impact some re gions more than others For example Stirling and colleagues 2007 found that the popula tion of polar bears in the Northern Beaufort Sea between 197172006 was fairly stable and attributed this to the fact that ice in this area does not melt completely While the western Hudson Bay population has eXperienced de clines linked to concomitant seaice changes the numbers of the most southerly population of bears in Southern Hudson Bay have remained stable since the mid1980s Obbard et a 2007 Howeven they have also eXperienced declines in body condition Obbard et a 2007 Declines in body condition of individuals in southern Hudson Bay were most dramatic for pregnant females and subadults and may be a precursor to a population decline Obbard et a1 2007 In their report to the US Fish and Wildlife Service commission evaluating the status ofpo lar bears Amstrup and coworkers 2007 pre dicted a loss of twothirds of the worldwide polar bear population by around 2050 They used two approaches to model polar bear pop ulations in the future 1 a model of carry ing capacity based on a presumed linear re lationship with average seaice extent and 2 a Bayesian network model which included sea ice loss as well as other stressors They placed the world s 19 de ned polar bear populations into four ecoregions and included 10 Global Climate Models to give minimum maximum and ensemble combination of all 10 seaice projections and made predictions at 45 75 and 100 years into the future For all combi nations of time steps global climate models and ecoregions both total and optimal polar bear habitat were lower than at present Under both modeling approaches polar bear popu lations were forecast to decline throughout all of their range during the 21st century Min imal iceeXtent projections predicted eXtirpa tion of bears from the Polar Basin Divergent Molina et ul Changes in Ice Dynamics and Polar Marine Ecosystems Ecoregion which includes the southern Beau fort Chukchi Laptev Kara and Barents sea regions of Alaska Russia and Norway by 2052 and from the Seasonal Ecoregion which in cludes the Baf n Bay Hudson Bay Davis Strait and Foxe Basin areas of Canada and western Greenland by 2082 Amstrup et a 2007 Despite the overall severe negative impacts on polar bears in some areas seaice losses may be temporarily bene cial Stirling amp Derocher 1993 Derocher et a1 2004 Bears in northern regions dominated by solid fast ice may have greater access to prey if leads and ice edges develop In addition declines in ice may in crease levels of biological productivity As the top marine predators of the Arctic ecosystem they depend upon every trophic level below for survival Thinning ice and increases in leads of open water creation of more ice edges may in crease levels of primary production Sakshaug et a 1994 which leads to healthy seal popu lations Stirling amp Derocher 1993 Seals them selves thrive in areas of moderate ice cover thick perennial multiyear ice is poor habitat for seals Kingsley et a1 1985 The success of polar bears is inseparable from the breeding success ofseals As many as 80 ofthe seals that polar bears kill are youngoftheyear Stirling 2002 Polar bears reach their minimum weight in Marchjust before seal pupping begins and rely on feeding on fatty seal pups to build suf cient fat reserves to survive in winter Stirling et a1 1999 Indeed especially heavy ice in the eastern Beaufort Sea in the mid l 970s andmid l980s caused a decline ofringed seal pups and therefore of polar bear natality Stirling 2002 Stirling amp Lunn 1997 Another iceassociated uppertrophic pre dator facing population declines is the ivory gull Pagaphila ebumea Ivory gull declines may even be in part linked to diminishing polar bear populations The ivory gull is the most northerly breeding bird in the world Blomqvist amp Elander 198 l and even in the nonbreeding season they rarely leave the pack ice Gilchrist amp Mallory 2005 Because oftheir inaccessibil ity few data are available on this species Nev 289 ertheless on the basis of local Inuit knowledge as well survey data it appears that the ivory gull is undergoing a major crisis in population de cline Mallory et a 2003 Chardine et a1 2004 Gilchrist amp Mallory 2005 In the Canadian High Arctic atsea observations in 2002 found onefourth as many ivory gulls as in 1993 cor rected for observation effort Chardine et a1 2004 Based on spatial surveys in Northern Canada in 200272003 compared with surveys in the l980s Gilchrist and Mallory 2005 esti mated an 80 decline in numbers noting that some previously occupied colonies are now de serted The exact mechanisms driving these declines are unknown Ivory gulls often scavenge on ma rine mammals killed by polar bears Summer hayes amp Elton l928 Salomonsen 1950 Char dine et a1 2004 so their numbers may be tied to the success ofpolar bears However the role that scavenging plays in the feeding behavior of the ivory gull may be overstated Renaud and McLaren l 982 noted scavengingbehavior off shore on the pack ice during aerial surveys in 197871979 but Divoky 1976 concluded from stomach contents that sh and invertebrates are the primary food source for this species with only rare opportunistic scavenging Chardine and colleagues 2004 also observed scaveng ing behavior but Blomqvist and Elander l 98 1 note that it is harder to observe birds foraging from the sea than feeding on carrion on oes so that the frequency of scavenging may be overestimated Other possible reasons for ivory gulls disap pearance include anthropogenic contaminants Braune et a1 2007 hunting Stenhouse et a1 2004 Gilchrist amp Mallory 2005 and relocation to new breeding sites deemed unlikely because of the large eXtent of aerial surveys Gilchrist amp Mallory 2005 Nevertheless for a species that spends its entire life history associated with sea ice changes in habitat may be the ultimate problem The ivory gull nests on nunataks is lands of bedrock surrounded by rough pack ice As the ice around them smooths or dis appears altogether nunataks no longer afford 290 protection from predators such as the Arctic fox Krajick 2003 Their wintering grounds thought to be between Greenland and Canada may also be undergoing major change in this area sea ice has actually increased since the 1950s and may be depriving the gull of cru cial ice edges needed to get at its prey Kra jick 2003 Whatever the cause ofthis seabird s decline recovery will be slow In contrast to most larids Lack 1968 which display a xed clutch size of three eggs the ivory gull gener ally lays two or less frequently only one egg Blomqvist amp Elander 1981 Like many high latitude breeders they have a low reproductive rate which may inhibit recovery of the species 22 The Southern Ocean 227 Rela onship befween Sea Ice and Anfarc c Krill Antarctic krill Euphausia superlm long con sidered a keystone species in the Southern Ocean are inextricably linked by nature of their life history to the dynamics ofthe seaice environment Quetin et a1 2007 This long 1ived 5 years Siegel 2000 and references therein zooplankter spawns in the austral sum mer Siegel 2000 Quetin eta 1996 and during the preceding months depends heavily on a1 gal food resources including those associated with retreating sea ice to fuel reproduction Quetin et a 1996 Krill larvae spend their rst summer and early spring feeding primar ily as herbivores in the upper mixed layers but are presumed to be largely dependent on ice associated food resources algae in particular to meet their energetic demands during win ter Frazer et al 2002a The timing of sea ice formation and the areal extent of seaice coverage during the winter are in fact critical factors affecting larval survival and subsequent recruitment to the adult population Ross amp Quetin 1991 Quetin et a1 2007 Recently doc umented increases in regional air temperatures along the Antarctic Peninsula and concomitant reductions in seaice cover Smith et al 1999b Smith amp Stammerjohn 2001 are a legitimate Annals of the New York Academy of Sciences concern as they pose a threat not only to krill but the myriad organisms in this region which depend on this species either directly or indi rectly Laws 1985 Croxall et a1 1999 Everson 2000 Here we review further the nature of the relationship between krill and sea ice Favorable winter ice conditionsiextensive spatial extent and long durationiare key to the reproductive success of krill particularly along the Antarctic Peninsula where they are the dominant zooplankton Ross et a 1996 Adult krill in this region exhibit a high repro ductive potential but require substantial en ergy intake to achieve maximum reproduc tive output see Quetin et a1 1996 Extensive iceedge phytoplankton blooms associated with the retreat of annual sea ice serve as an im portant food resource in this regard Highice years which result in a favorable food environ ment promote early gonadal development and spawning Hofmann amp Powell 1998 which in turn afford larvae a protracted feeding inter val Ross et a 2000 prior to the onset of win ter when phytoplankton concentrations in the water column are extremely low Stretch et a 1988 Daly 1990 Smetacek et a 1990 Ross amp Quetin 1991 Larval krill do not tolerate prolonged periods ofstarvation Ross amp Quetin 1991 This would appear to present a signi cant ecological chal lenge for these early life stages during their rst winter when primary production in the South ern Ocean is at a minimum due to the marked reduction in solar irradiance Smith et a1 1996 It is now generally accepted however that krill larvae survive the winter by exploiting food resources algae in particular that are closely associated with and often concentrated in the annual seaice habitat Marschall 1988 Daly 1990 Smetacek et a 1990 Frazer et a 1997 Frazer et al 2002a 2002b Quetin et a1 2003 and references therein Prior to formation of annual sea ice in winter larval krill feed primar ily as herbivores ltering phytoplankton and other particles from the upper mixed layers of the Southern Ocean Ross amp Quetin 1991 Frazer 1996 Ross et a1 2000 They exhibit a Molina et ul Changes in Ice Dynamics and Polar Marine Ecosystems remarkable modi cation of this typical feeding behavior in the winter when sea ice is present rather than ltering the water larval krill scrape algae and other food sources from its surfaces Frazer et a 1997 The onset of seaice formation and maXi mum areal coverage are hypothesized to be two of the most important factors affecting the overwinter survival and recruitment success of larval krill Quetin et a1 1996 If ice forma tion is delayed that is if it occurs late in the winter then growth and development may be delayed and starvation is possible Quetin et al 200 3 Similarly if the areal eXtent of ice cover is reduced larvae that occupy waters farthest offshore may not encounter suitable habitat and may suffer a similar fate Ross and Quetin 1991 demonstrated in fact that larval krill collected during the winter in a heavyice year 1987 were in better physiological condition than larvae collected during a winter with low ice cover 1989 During the winter with high ice cover larvae eXhibited higher growth rates and had higher lipid content and increased con dition factors Seaice cover during winter has been demon strated by numerous investigators to be corre lated with recruitment success of krill Siegel and Loeb 1 995 found that both the spatial and temporal components of winter ice cover af fected krill recruitment in the Antarctic Penin sula region Quetin and Ross 2001 in a sep arate time series analysis also found a strong correlation between the timing and eXtent of winter seaice formation and krill recruitment In both cases krill recruitment success was greatest during highice years Quetin and col leagues 2003 suggest however that the com pleXities in sea iceikrill interactions are not yet fully understood and the mechanisms resulting in increased growth and survival of larval krill are likely multifaceted There is now compelling evidence for recent climateinduced changes in the timing and eX tent ofseaice coverage in the Southern Ocean Stammerjohn amp Smith 1996 Smith amp Stam merjohn 2001 These changes are most pro 291 nounced along the western Antarctic Peninsula VVAP Smith et al 1999b Domack et a1 2003 Vaughan et a1 2003 a region where krill stocks have historically dominated the zooplankton assemblage Ross et a 1996 A reduction in seaice cover and concomitant changes in hy drographic patterns see Hofmann et a1 1996 Nicol 2006 are likely to have a profound in uence on the abundance and distribution of krill and other zooplankton see Loeb et a1 1997 and also those species that depend on krill either directly or indirectly Smetacek amp Nicol 2005 Nicol 2006 Ducklow et a 2007 The immediate consequence to adult krill of reduced seaice coverage especially along the Antarctic Peninsula is a change in the produc tion characteristics of the phytoplankton as semblage that typify the region Melting sea ice in the austral spring is thought to seed the surface waters with algae Smetacek et a1 1990 Nicol 2006 which in turn stimulates extensive iceedge phytoplankton blooms see Smith et a1 1 996 that provide an abundant food source to fuel krill reproduction Reduced sea ice cover and resultant decrease in the availabil ity of phytoplankton associated with iceedge blooms is expected to be manifest as poor re productive output by krill and subsequent re duction in yearclass strength see Hofmann amp Powell 1998 Siegel 2005 Recurrent reduc tions in the spatial eXtent of ice coverage are likely to have marked effects on the age struc ture and population size of krill Siegel 2005 with cascading foodweb effects Smetacek amp Nicol 2005 Changing seaice and oceano graphic conditions may in fact favor other zoo plankton species see Loeb et a1 1997 resulting in fundamental changes in the structure of the pelagic food web Moline et a1 2004 Krill lar vae too are clearly susceptible to declines in seaice cover Ross amp Quetin 1991 Annual sea ice provides both a forage and refuge habi tat Ross amp Quetin 1991 Quetin et a1 1994 Frazer 1996 Frazer et a1 1997 for larval and juvenile krill A reduction or absence of annual seaice cover in both space and time is likely to compromise the physiological condition of 292 these vulnerable early life stages Ross amp Quetin 1991 Quetin et a 2003 and under extreme circumstances starvation and yearclass failure might be expected to occur Interannual variation in the timing of seaice formation and extent of areal ice coverage is an inherent characteristic of polar environments In fact ecosystem dynamics in the Southern Ocean are dominated by the seasonal processes of ice formation and ice retreat Ducklow et a1 2007 Krill by virtue of their relatively long life span are adapted to deal with this dynamic and occasional years of reduced reproductive output or poor larval survival in response to unfavorable ice conditions are not generally reason for alarm Siegel amp Loeb 1995 Hof mann amp Powell 1998 However any change in climate that results in chronic delays in the timing of ice formation andor the extent of areal coverage is indeed a legitimate reason for concern Successive yearclass failures as a con sequence of low ice cover are likely to have pro found effects on krill population structure and may lessen this species resilience to other po tential anthropogenic in uences such as com mercial shing see Agnew amp Nicol 1996 Hof mann amp Powell 1998 By way of analogy we point out that the combined effects of large scale climate anomaliesiENSO evenmiand commercial harvest led to the collapse of the Peruvian anchovy shery It may be prema ture to draw such a parallel but it does serve to reinforce the potential signi cance of the issue 222 Dependence of Anfarc c Fishes on Sea Ice The sh biota of the Antarctic is composed of two faunal types Antarctic endemics that are primarily benthic as adults and repre sentatives of sh families that are widely dis tributed in the world ocean DeWitt 1970 Eastman 1993 About 95 species belonging to ve families in the perciform suborder Notothe nioidii Artedidraconidae Bathydraconidae Channichthyidae Harpagiferidae and No totheniidae dominate the shelf and slope of the Annals of the New York Academy of Sciences Antarctic benthos Andriashev 1965 Eastman 1993 However in most regions ofthe coastal Antarctic only two species occupy the pelagic waters between surface and bottom as adults the Antarctic silver sh Pleuragmmma antarcticum and the Antarctic tooth sh Dismstichus mawsani The WAP shelf is an exception to the prevalent Antarctic pattern Oceanic species are present as adults in appreciable numbers up to 50 of the pelagic sh biomass in the pelagic regions of the WAP shelf the most important being the lantern sh Electnma antarctica Lancraft et a 2004 Donnelly amp Torres 2008 For shes the in uence of sea ice and the cold temperatures that accompany it go be yond the simple roof on the ocean that acts as a barrier to penetration of light Temper atures below 1 C will normally freeze the blood of marine shes DeVries 1986 unless they are protected by biological antifreezes Most continental shelves in the Antarctic have surface to bottom temperatures 2OC Din niman et a1 2003 that would rapidly freeze unprotected shes Once again the WAP shelf is an exception with largely positive tempera tures in waters below 100 m Smith eta 1999a making it a more hospitable environment for shes In most coastal systems of the Antarc tic the edge ofthe continental shelfde nes the boundary between the coastal and oceanic sys tems DeVVitt 1970 Donnelly et a1 2004 Don nelly amp Torres 2008 with the oceanic shes not present landward of the shelf break It has been tacitly assumed though never exper imentally demonstrated that oceanic species are excluded by the very low temperatures in shelf waters Recently acquired data Sorge De Vries and Torres unpublished data suggest that oceanic species lack antifreezes giving cre dence to the hypothesis Changes in the maximum extent of winter sea ice and timing of seaice advance and re treat have the potential to in uence shes liv ing in both coastal and oceanic systems A pri ori it would be expected that the most critical changes would be those in uencing vulnera ble periods in species life histories What rst Molina et ul Changes in Ice Dynamics and Polar Marine Ecosystems springs to mind when critical periods are be ing considered is the period of larval develop ment Fish species that use sea ice for spawn ing and as an early nursery such as the silver sh Pleuragmmma antarcticum Vacchi et a1 2004 and the yellowbelly rock cod Nuwthmia cariiceps Kellermann 1996 or as a site for rstfeeding pelagic larvae such as the channichthyid Chilmi admcu rastrispinasus Kellermann 1996 will be heavily impacted by changes in seaice timing and eXtent In contrast species that show lit tle direct dependence such as the lantern shes Electnma antarctica and nymnuswpelus braum39 Efremenko 1986 will likely show minimal impact Assessment of the effects of a changing ice cover on the Antarctic sh community is complicated by the diversity of Antarctic sh life histories and reproductive strategies even among the notothenioids Reproductive strate gies range from demersal spawning followed by a prolonged period of nestguarding un til the eggs hatch eg Harpagtfer bispinis and 1422210710me nudjfmns Daniels 1978 Houri gan amp Radtke 1989 respectively to broadcast spawning of pelagic eggs Electnma antarctica and Pleuragmmma antarcticum Efremenko 1986 Vac chi et a1 2004 It will be most instructive to brie y de scribe elements of the reproduction early life and growth pattern of four Antarctic shes to gain an appreciation for the diversity em bedded in the system two pelagic species Electnma antarctica and Pleuragmmma antarcticum the semipelagic ice sh Chilmudma msmspinasus Channichthyidae and a nestguarding no totheniid species 1212150710th 7114419912713 Sea ice extent the timing of its retreat and advance and the initiation of the productive season have been variables in the lives ofall shes living in the seasonal ice zone over the course ofevolu tionary time As a consequence a considerable amount of tolerance has been incorporated into their early life histories Electnma antarctica is the southernmost repre sentative of the globally distributed family Myc tophidae Its distribution is primarily oceanic 293 Hulley 1990 ranging fromthe Antarctic Polar Front to the edge of the Antarctic continental shelf in all but the WAR where it is common in shelfwaters Donnelly amp Torres 2008 It is an important prey item in the diets of ighted seabirds and penguins Ainley et a 1986 Elem tram lives for approximately 4 years with the females reaching a length ofjust over 100 mm in their fourth year of life Greely et a1 1999 and is a batch spawner reproducing multiple times in its nal year Efremenko 1986 Greely et a1 1999 Its larvae can be found year round with peak numbers in the summer and fall Table 1 Efremenko 1986 In the winter lar vae of Electnma are found primarily below 200 m of depth Efremenko 1986 Kock 1992 in the waters of the Antarctic Circumpolar Cur rent speci cally in the warmer 20 C layer formed by the CDW During the spring and summer they rise into the 1007200 m layer Efremenko 1986 Feeding habits oflarvalEZeci tram are undescribed but the smaller stages lt45 m feed primarily on calanoid and cy clopoid copepods Rowedder 1979 Hopkins 1985 Pakhomov et a 1996 which are most abundant during the productive months of the spring and summer Older shes are primar ily euphausiid feeders Hopkins 1985 Lancraft et a1 2004 Pleuragmmma antarcticum is the dominant pelagic sh in most coastal regions of the Antarctic It is found between the shelf break and the continental margin in all areas of the Antarctic that have been sampled DeWitt et a1 1990 It is considered to be a high Antarctic species Hubold 1985 Kock 1992 though it is also found in the zone of seasonal sea ice notably in the shelf waters of the WAP Lan craft et a1 2004 Donnelly amp Torres 2008 In a recent review on the role ofnotothenioid sh in the food web of the Ross Sea the authors state that Pleuragmmma antarcticum dominates the diet of all top predators from the Antarc tic petrel to the Weddell seal La Mesa et a1 2004 Several species of shes also feed princi pally on Pleuragmmma Eastman 1985 making it a critical trophic link in the coastal system TABLE 1 Age and elements of the early life history of four species of Antarctic fishes Species Life habit adult Maximum Sexual maturity y Oocyte Duration of diameter mm larval stage 1110 Spawning H atching Source E whom antamim Plzmagmmma antantimm Chianoa mw my my Mom Lz ia onoto zm nudp mm oceanic pelagic on packice zone coastal pelagicnot found off shelf seasonal packice zone to high Antarctic coastal semipelagic seasonal packice zone coastal benthicinshore seasonal packice zone 4Mar 5 1124114 F5 241 all year peak in AprAJun AugASep Fe beMar Mayejune all year peak in DecAMar Nov Augep O CtANOV Efremenko 1986 Kock 1992 Greely Kid 1999 Hubold and Torno 1989 Radtke Kid 1993 Hureau 1966 Kellerrnann 1996 Hourigan and Radtke 1989 Radtke and Hourigan 1990 294 Annals of the New York Academy of Sciences Molina et ul Changes in Ice Dynamics and Polar Marine Ecosystems In the one place where Pleuragmmma eggs were de nitively located and collected Terra Nova Bay in the Ross Sea Vacchi et a 2004 they were found oating in the platelet ice un derneath 13 m thick sea ice They were found to be hatching within the ice starting in mid November This was a very important nding since it suggests that seaice cover is very impor tant to Pleuragmmma s early life history In addi tion it con rms that Pleuragmmma has pelagic eggs a conclusion rst reported by Faleyeva and Gerasimchuk 1990 in a histological study on the gonads of Pleuragmmma Time of hatch ing is consistently in the NovemberiDecember period in the three areas of the Antarctic where data are available the Antarctic Peninsula and the Ross and Weddell Seas Kellermann 1986 Hubold amp Tomo 1989 Kock and Kellermann 1991 Vacchi et a1 2004 Pleuragmmma hatched at an average length of 93 mm in the Ross Sea with a range of 8710 mm Vacchi et a1 2004 Hubold 1990 reported an average length of 9 mm for newly hatched Pleuragmmma in the Weddell Sea sug gesting that variability in size at hatch is min imal from place to place Pleuragmmma don t reach their juvenile silver sh appearance un til in their third year age class AC 2 oflife at lengths of 60790 mm Rings presumed to be annular in Pleuragmmma otoliths suggested that the sh s largest sizes 2457250 mm were about 21 years old Hubold amp Tomo 1989 Data on lengthatage obtained by reading otolith microincrements daily rings with a scanning electron microscope suggested that Pleuragmmma were far older a 205 mm sh was determined to be 335 years of age Radtke et a1 1993 At the moment what is most certain is that Pleuragmmma is a slowgrowing longlived sh even when compared to other Antarctic shes Fishes AC 2 and younger are found primarily in the upper 200 m with the youngest shes found most shallow Lar val and juvenile silver sh feed primarily on copepods though polychaetes pteropods and chaetognaths are taken as well Hubold 1985 Older shes feed primarily on euphausiids ei 295 ther Euphausia superba or crystallomphias DeWitt amp Hopkins 1977 Visual and histological studies Faleyeva amp Gerasimchuk 1990 suggest that sh collected in the Mawson Sea spawn at 13716 cm stan dard length SL for the rst time Hubold 1985 reported that sh in the Weddell Sea rst show gonadal development at a size of 125 cm and Reisenbichler 1 993 reported that Mc Murdo Sound sh showed appreciable gonad development at 16 cm Agreement between the three studies is reasonably good with a consen sus gure of 13716 cm Ifthe size at sexual ma turityg 13716 cm SL is applied to the Hubold and Tomo 1989 growth curve Pleuragmmma antarcticum begins reproduction at an age of 779 years or about 55 00 ofits maXimum size Kock amp Kellermann 1991 and reproduces each year thereafter for the remainder of its life It is believed that spawning takes place in the winten in the August September time frame and that embryos develop over a period of 60775 days prior to hatching Kellermann amp Schadwinkel 1991 This postulated incuba tion time seems quite rapid however Most re ported incubation times for Antarctic sh eggs hover in the neighborhood of 4 months Kock 1992 Spawning behavior of Pleuragmmma is unknown Howeven two lines of evidence pro vide suggestions First the data of Vacchi and colleagues 2004 con rm that Pleuragmmma has pelagic eggs and that they are found in high concentrations underneath the landfast sea ice in Terra Nova Bay Second the ob servations of Daniels and Lipps 1982 that thousands of Pleuragmmma were observed under landfast sea ice on three occasions in theJunei October period suggests that Pleuragmmma may form spawning aggregations under coastal sea ice in winter The ice shes exhibit a variety of lifestyles as adults ranging from nearly pelagic to ben thic Eastman 1993 in the shelf and slope waters of continental Antarctica and outlying islands Available data suggest that most ice shes ascend into the water column to feed on krill even when they reside primarily on the 296 bottom Eastman 19937hence the designa tion as semipelagic for Chianudmca rwtrispinasus Though distributions within the water column differ as adults the ice shes apparently share a common larval strategy Large 4175 mm yolky eggs are produced yielding a large larva 190 mm at hatch that is soon capable of preying on euphausiid furcilia and the smaller nototheniid larvae Chilmudmw msmspinasus hatches in the late winter Augustiseptember Kellermann 1996 and remains as a pelagic larva through the spring summen and following winter Its congenen C hamatus hatches in early winten also with a large 170 mm larva and simi lar feeding strategy The substantial yolk sac reserve allows the larvae a greater metabolic exibility in feeding during the winten and its resorption is variable depending on feed ing success Kellermann 1996 The ice shes thus show a considerable independence from the production cycle instead keying in on the availability of their prey nototheniid larvae and krill furcilia All have a prolonged pelagic larval phase Lepidunamthm nudy mm is a small lt166 mm SL benthic species distributed in the shallow waters of the Antarctic Peninsula and outly ing islands DeWitt et a1 1990 It is accessible by divers and shallow trawls thus allowing its breeding behavior to be observed in a labora tory setting Hourigan amp Radtke 1989 Lepe idanawthen nudy mm builds nests in crevices or on the underside of rocks during the months of May and June which are actively guarded by a male until the eggs hatch in 124 days About 30 of the females examined were gravid in the spring October two of which had spawned in the previous May suggesting that L nudy mm may produce multiple clutches Hourigan amp Radtke 1989 After hatching the small 70 mm larvae are positively pho totaxic swimming to the surface where they remain in a pelagic phase for a period ofabout 5 months about one productive season until they reach a length of 28 mm Hourigan amp Radtke 1989 before assuming a benthic exis tence Time in the plankton was estimated by Annals of the New York Academy of Sciences calculating the time to get to 28 mm from the growth curve of Radtke and Hourigan 1990 They are believed to feed on copepods in their smaller stages DeWitt et a1 1990 lepidunm tatLen nudz zms reaches sexual maturity in its fth year of life and lives for about 9 years Table 1 It should be clear from the brief exami nation of Antarctic sh life histories that the cycle of advance and retreat of the seasonal sea ice is an important element in the sur vival of many Antarctic sh larvae Two of the species described here Pleuragmmma antarcticum and Chilmudma ms ispinusus have a very direct interaction with the ice canopy Pleuragmmma apparently uses the underside of the ice as a nursery for its eggs and a feeding ground for its newly hatched larva Vacchi et a1 2004 The larvae of Chionadmw in contrast use the ice canopy as a hunting ground for iceassociated biota such as krill furcilia and nototheniid lar vae In both shes survivorship of larvae should theoretically be enhanced in those years that exhibit aboveaverage maximum ice extent In Pleuragmmma s case the ice would more likely be present for the entire incubation period of the eggs and the beginning of rst feeding for the larvae In that of Chionadmw the greater success of krill furcilia its primary prey during high ice years see section 221 Quetin et a1 1996 Loeb et a 1997 would favor larval survivorship Kellermann 1996 The limited data avail able support the supposition for Chilmudmca and other channichthyids in the Palmer Peninsula region Very high catches of channichthyid lar vae coincided with two years with anomalously high ice extent 198081 and 198788 Keller mann 1996 Pleuragmmma larvae also showed a peak in 198081 but a second peak in 198586 coincided with an anomalously low ice yean casting some doubt on the direct relationship Kellermann 1996 Larvae of Electnma and Lepidunamthm nudy mm depend more on secondary production which is enhanced at the retreating ice edge and the pro ductive period that follows the ice decay Smith amp Sakshaug 1990 SchnackSchiel amp Hagen Molina et al Changes in Ice Dynamics and Polar Marine Ecosyslems Hydnlrga Iepmnyx Mimunga tuning n are quot4 mm Bullenaplm bonawmi I e Mengra navnemglme I Lam minaphl Li maxim Aplenadytesjmsleri gm Plnemgmml m cum Czpllalnp Electmnaant 11m P o sychmlen lixglzlzinb39x d I Euplmmsia stigma Dissnlved cm 3533 Phytoplankton Figure 16 Deptcltons oi tne iood web dlong tn ltgnted in bold gray to illustrate tne importance oi ice e Antarctic Peninsula Sympdgtc organisms me We to tne toodweb structure Dotted lines me around pnytopldnkton dnd copepo 5 15 not all me me dependent Food web was generated based on interactions documented in tne lttetdtute 1994 In theory survivorship of both species would be enhance 39 and copepodites for rstfeeding larvae Keller mann 1996 At thisjuncture insuf cient data exist to determine if larval success of either species tracks with ice cover Little doubt exists that peaks and valleys in the extent of seasonal ice cover and the tim ing of its advance and retreat have the poten tial to in uence the survivorship of Antarctic shes The regional warm currently occur ring in the Palmer Peninsula region Ducklow 52 a1 2007 is an experimentin progress that will likely change the character ofthe sh commu nity there with repercussions up and down the trophic pyramid Fig 16 223 Climateinduced Changes in the Ecology ofAd ie Penguins Antarctic marine food webs were once per ceived as being relatively simple a notion that arose at least in part from the observation that the dies of most of Antarctica s top preda tors seabirds pinnipeds and cetaceans were domina e by a 39mited number ofprey species aws 1985 Although research during the last three decades in particular has demonstrated that these marine food webs c plex as they are in temperate or even tropical oceans Barnes amp Conlan 2007 Clarke 52 a1 2007 an important aspect ofthese earlier ob servations has not only proven to be correct but in fact provided key insighm into the mechanis tic processes linking predatoriprey dynamics 298 Thus while the perception that Antarctic top predators consume a relatively small number ofprey species is correct the reason is not that prey diversity is low but rather that the num ber of species regulating energy ow between primary producers and top consumers often tends to encompass only 375 trophic compo nents Laws 1985 Knox 1994 2007 Antarc tic marine food webs in other words tend to be short and the few key species involved usually dominate system dynamics in terms of both numerical abundance and standing biomass These attributes of Antarctic marine food webs have been instrumental in advancing our understanding of the relationships between ecosystem structure and function for two im portant and related reasons The rst is that with less trophic complexity causal relation ships are easier to detect above background noise Reid eta 1999 Fraser amp Hofmann 2003 Murphy et a 2007 The second is that as a result changes in the biogeography andor population dynamics of marine top predators such as Adelie penguins Pyguseeh39s adeh39ae of ten constitute the rst evidence that food webs may be responding to climateinduced forcing This is addressed by Fraser and Trivelpiece 1996 within the context of both evolution ary and contemporary time scales Adelie pen guins have evolved life histories that are depen dent on sea ice As longlived wideranging top predators they subsequently integrate the effects of variability in seaice dynamics over large spatial and temporal scales The expres sion of this variability can for example be measured annually as iceinduced changes in breeding success Ainley 2002 or over the course ofmillennia as changes in biogeography associated with epochs of Antarctic warming and cooling Emslie 2001 Emslie et a 2007 Both empirically and conceptually the matchi mismatch hypothesis Cushing 1990 has provided a fundamental perspective for under standing these dynamics This tenet is the focus ofthis section and is applied in this case to illus trate how iceinduced changes in Antarctic krill Annals of the New York Academy of Sciences populations due to climate warming are affect ing aspects ofthe ecology ofAd lie penguins in the WAP region The WAP marine ecosystem extends for c 1500 km from its northern tip at 63 S to the Bellingshausen Sea at 75 S and the shelf av erages 200 km in width and 400 m in depth Hofmann et a 1996 Ducklow et a 2007 The WAP as a whole has experienced signi cant warming of surface air temperatures 2 C increase in annual means since 1950 but it is the midwinter record in particular that shows the strongest and most statistically signi cant trends Smith eta 1999b Indeed this record reveals a warming of 576 C over the last 50 years which is unique within the last few mil lennia and exceeds any other rate on Earth since the beginning of the modern instrument record Smith eta 1999b Domack eta 2003 Vaughan et a 2003 Ocean warming has also occurred and is intensi ed toward the surface above 100 m where an increase ofover 1 C has been detected since the mid1950s Meredith amp King 2005 These profound changes in WAP surface sea and air temperatures have had profound effects on the presence and timing of seaice advance and retreat across a range of spatial and tem poral scales These include for example a de crease in the frequency of occurrence of cold years with heavy seaice conditions Fraser eta 1992 Loeb eta 1997 a longterm reduction in seaice concentrations Vaughan eta 2003 Liu eta 2004 and changes in the overall length of the seaice season Parkinson 2002a The latter which is based on a remote sensing record that began only in 1978 is within this context noth ing short of dramatic indicating that the length of the seaice season has decreased by nearly 3 months as a result ofsea ice advancing signif icantly later and retreating signi cantly earlier Stammerjohn eta in press Rhodes and Odum 1996 suggest that one of the mechanisms by which climate warm ing induces change in ecosystem structure and function is its disruption of the evolved life his tory strategies of key component species This Molina et ul Changes in Ice Dynamics and Polar Marine Ecosystems concept forms the mechanistic core of the matchimismatch hypothesis and fundamen tally implies that life history strategies will re main successful in a changing environment only if the range of variability in space and time of the critical resources they require to remain viable does not exceed the thresholds under which they evolved Fraser amp Trivelpiece 1996 Forcada et a1 2006 Both Antarctic krill and Ad lie penguins have evolved life histories that are critically dependent on the availability of sea ice and changes in the spatial and tem poral dynamics of sea ice in the WAP have been implicated as key factors in the signi cant population decreases both these species have experienced in the region during the last 3 decades Fraser et a 1992 Trivelpiece amp Fraser 1996 Fraser amp Patterson 1997 Loeb et a1 1997 Siegel et a1 1998 Atkinson et a1 2004 Forcada et a 2006 Hinke et a1 2007 Although it is beyond the scope of this sec tion to discuss these trends and their causal relationships in detail see Clarke et a1 2007 Ducklow et a1 2007 and Murphy et a1 2007 for recent reviews the matchimismatch hypothe sis provides a clear foundation for understand ing how climate warming and a loss of sea ice in the WAP is changing the phenology of krill abundance and availability to Ad lie penguins variables that contribute directly to important regulatory processes affecting their population dynamics Fraser amp Hofmann 2003 Ad lie penguins have long been regarded as a krilldependent species in the WAP Conroy 1975 Volkman et a 1980 Krill their primary prey are from abiomass perspective one ofthe most abundant organisms in the world s oceans Verity amp Smetacek 1996 Moreover the fact that krill are also phytoplankton grazers exem pli es both the short nature of these Antarctic marine food webs and the dominant ecologi cal role held by such key secondary consumers associated with them Laws 1985 Knox 2007 How changes in the abundance and availabil ity of krill affect Ad lie penguin populations however involves at least two scales of responses that share a common periodicity of 475 years 299 Fraser amp Hofmann 2003 and which are ul timately linked to interactions between WAP climate warming and changes in the phenol ogy of seaice development Fundamentally in the absence of sea ice krill cannot reproduce successfully enough to main tain their populations see section 221 This relationship ensues from the fact that because winter water column primary production is at a minimum krill larvae have evolved a depen dence on underice algae as a primary food source to survive their rst winter of life af ter hatching Daly 1990 Ross amp Quetin 1991 Quetin amp Ross 2001 Krill recruitment and yearclass strength are as a result not only strongly dependent on the presence of sea ice but in fact episodic in the WAP linked to years during which the phenology of winter seaice development is spatially and temporally coher ent with the evolved requirements of this criti cal aspect of krill reproduction Fraser amp Triv elpiece 1995 Siegel amp Loeb 1995 Loeb et a1 1997 Reid eta 1999 Fraser amp Hofmann 2003 Quetin amp Ross 2003 Quetin et a1 2007 According to Fraser and Hofmann 2003 years of optimal seaice conditions conducive to good krill recruitment and strong yearclass development in the WAP are occurring on av erage only once every 45 years Stated dif ferently serial mismatches now appear to be a dominant pattern affecting WAP krill popula tion dynamics and indeed this pattern also represents an important metric insofar as un derstanding the responses and consequences to top predator populations such as Ad lie penguins As previously suggested at least two scales of responses are involved The rst is illus trated in Figure 17 which shows that episodic recruitment leads to equally episodic changes in krill abundance However because serial mis matches result in no additional recruitment the abundance of the strong krill cohorts pro duced diminishes over time until the popula tion is again replenished by another recruit ment event As seen in Figure 17 Ad lie pen guin foraging trip durations respond on very short time scales annual to these recruitment 300 E 100 vFomgxng rnp Duration 7 g Mummy 2quot 3 so 258 g 2043 s so 5 z 15 g g 40 3 3 a 3910 s g 20 5 g 9 e E n 89 90 9E1 91432 92793 9344 913795 9596 Sr 7 4 1 2 3 4 t 2 3 FieldSEason Fi ure 17 VGHGlDllHy m Adehe pengum forogr m mp durations lled wales new Palmer Station m relation to lolll stock density gray phont lslond T e num ers elow eslgnote me yem classes be number Winters conducive to good lolll recruwmem and the urn ers and 4 track the trends m lolll stock density associated wnb each remunmem event The table 15 adopted from Fraser and Hofmonn 2003 and Used by permlsslon events and closely track the resulting changes in 39quot L 4 between 39 Modeling studies based on these data Sali hoglu 52 a1 2001 Chapman 5 al in press sug gest that these serial mismatches can negatively affect parental chick feeding rates leading ulti mately to Adelie penguin chicks whose edging weighs are insuf cient to guarantee their own 0 nter survival which in turn com ro mises their future recruitmentinto the breeding population The second scale of response is shown in Figure 18 Adelie penguin breeding popula 39on n mbers in the vicinity ofPalmer Station 64 46 S 64 04 VV Anvers Island have exhib ited a 65 decrease during the years 1974 2005 This change however has not been lin ear exhibiting in general a more rapid and statistically signi cant rate of decrease during the post1990 period VVoehler 52 a1 2001 and speci c years of particularly large stepwise changes in 1987 an 2001 w en the po ula tion decreased by 20 and 19 respectively relative to the previous years 1986 and 2000 censuses he more remarkable features about krill life history is their 54 year longevity Annals of the New York Academy of Sciences which is unique among euphausiids Nicol 1990 Siegel amp Kalinowski 1994 Verity amp Smetacek 1996 and which Fraser and Hof mann 2003 proposed is playing a pivotal role in contemporary matchimismatch dynamics if one considers that seaice conditions conducive to good krill recruitment are manifesting on av erage only once every 475 years Indeed a de tailed analysis ofsea ice conditions and recruit ment frequency by these authors in the decade prior to 1990 revealed that cohort senescence may have greatly diminished the reproductive otential ofthe three strong age classes gener ated during the early part ofthe decade 1979 1980 1981 because it was not until 1986 or 57 6 years later that seaice conditions were again suitable for krill reproduction Loeb 52 a1 1997 Siegel 52 a1 2002 Fraser amp Hofmann 2003 These krill senescence evens likely explain the 20 decrease in Adelie penguin population numbers observed in 1987 Fraser amp Hofmann 200239 Fnrcarla 9006 and the 19 decrease noted in 2001 as a 5year gap also separates 2001 from the previous strong krill year class which was produced in 1996 Loeb a a1 1997 Siegel 52 a1 2002 Fraser amp Hofmann 2003 Within the context of matchimismatch dynam ics these senescence events may therefore be have as additional ecosystem stressors whose effecm have decadalscale consequences from which some krilldependent predator popula tions whose life histories are also reliant on sea ice may not recover concluding it should be noted that the rather focused nature of this discussion is not meant to dismiss or simplify the i portance of other processes that are affecting WAP top predator populations and marine system d namics However as Verity and Smetacek 1996 observe marine ecosystems select the life histories of the s ecies that o ulate them It is not surprising therefore that the predatoriprey dynamics explored in this section have analogs that are temporally co herent over spatial scales that include the sea ice zones of the northern WAP and much of the southwest Atlantic sector of the Southern Molina el al Changes in Ice Dynamics and Polar Marine Ecosystems inn Adeliz Penguin Buzdingl npulatim n 1975 1975 ml um um um um ml min um um mun ml mm min 2ou 2mm YEAR Figure 18 Longrlerm population trend of Ad lle pengmns breeding in Me Vicinity of Palmer Smnon Anvers island WAP Tne trend is based on percent cnange in breeding pans relative to Me firslcensus m 974 Ocean importantly they also involve other krilldependent predator groups besides Adelie penguins Fraser amp Hofmann 2003 Forcada 52 a1 2006 Hinke 52 a1 2007 Murphy 52 a1 2007 3 Indirect Impacts of Changing Polar Hydrogruphy 31 The Arctic Ocean 311 Expansion of North Atlantic Water and Food Web Impacts Atlantic sector of the Arctic has ex perienced widespread warming and declines in ice extent Species normally found further south have recently extended their range north ward eg Berge 52 a1 2005 The southwest coast of Spitsbergen is a particularly dynamic area with heterogeneous oceanographic con ditions Fig 19 There are two water masses found off the southwest coast of Spitsbergen the Sorkapp current sometimes also referred to East Spitsbergen current and the West Spitsbergen current Fig 19 Swerpel 1985 Swerpel amp Zajaczkowski 1990 The West Spimbergen current ows north and originates in the North Atlantic It is characterized by warmer temperatures and carries with it a small species of copepod Calamm nmmthuux The Sorkapp current also ws north a er turning around the southern tip of S imber gen Fig 19 The Sorkapp current is char acterized by cold temperatures an it con tains high densities ofthe larger more energy rich copepod Calanu glamah Karnoysky a a1 2003 The distribution and strength of these cur renm Varies interannually eg Schlichtholz amp Sorkappcurrent Figure 19 There are two currenrs Howmg norm along the SW coasr of Spitsbergen the Atlantic derlve l Wesr Spitsbergen currenr and the cold Arcrrcderrved Sorkapp currenr Goszczko 2006 Increases in Atlanticderived water into the region have been linked to pos itive phases of the North Atlantic Oscillation NAO Dickson 32 a1 2000 The NAO index is based on the difference between sealevel air pressure measured in Lisbon Portugal and Stykkisholmer Iceland and has been measured since 1864 Hurrell 1995 Hurrell 52 a1 2001 Since the 1990s the NAO has been in a pre dominantly ositive 39 exceptionally high magnitudes Hurrell 1995 which may be linked to anthropogenic warming Visbeck 52 a1 2001 After strong positive NAO phases there is an expansion ofAtlanticderived water in the region Blindheim 52 a1 2000 Mork amp Blind heim 2000 Schlichtholz amp Goszrzko 2006 Vinje 2001 found that ice extent in the re gion has declined over the past 135 years and that positive phases of the NAO measured in winter are negatively correlated with ice extent measured in April In addition to changing the ice conditions this in ux in uences the entire Arctic food web Annals of the New York Academy of Sciences One way that increases in Atlantic water in the region change the marine food web is by advecting into the region the small boreal species of copepod Calanux nmm huu as op posed to the Sorkapp current s larger more lipidrich oopepod Cahmu glacwa Gaschnov 1961 Hirche 1991 Unstad amp Tande 1991 Karnovsky a a1 2003 The larger Arctic species C gland has 10 times the amount of lipids as C mmmhuu FalkPetersen 52 a1 2006 On the basis of net tows in both wa ter masses in the upper 50 m of the water column adjacent to Hornsund Fjord on the side of Spitsbergen Karnovsky and col leagues 2003 found that the energy content of Calanu copepods in these water masses differed greatly They estimated that there was only 22 k m 3 of energy available in largesize oope ods in the West Spitsbergen current Atlantic derived water whereas the energy content of the Sorkapp current Arcticderived water was 69 k nr3 Karnovsky et a1 2003 Interest ingly densities of zooplankton did not differ substantially between the two water masses Karnovsky 52 a1 2003 Therefore zooplank tivorous predators would have to spend three 39mes as ong to meet their energy needs when feeding in the Atlanticderived water 5 ass The Arctic marine food web is highly de pendent on the consumption of large size Calanu cope ods e Karnov unt 2002 Karnovsky 52 a1 2003 Therefore in Atlantic water in the region could have widespread repercussions for the Arctic marine food web in the region which includes many marine mammals and seabirds The dovekie A1112 alle for example is a zoo planktivorous seabird eg W slawski 52 a1 1999 Karnovsky 52 a1 2003 which nests along the west coast of Spimbergen Norderhaug 1980 Stempniewicz 1981 While it can eat a diversity of zooplankton prey the dovekie relies heavily on Calanu copepods to feed both them selves eg Karnovsky amp Hunt 2002 and their chicks eg Karnovsky 52 a1 2003 Dovekies can dive up to 35 m in search oftheir prey Falk creases in warm Molina el al Changes in Ice Dynamics and Polar Marine Ecosyslems 7 1 9 am 2001 2003 n so 7 Dalanus glacian39s D D Calanus nmarchicus ll other I 5 cm W Calanus hyperboreus 95 2004 6 n BS quot7 Figure 20 Percentobundonce oi differemzooplonklon prey delivered to chicks by W 03 e mber o i k Visioning adult dovekies m 2001 20 52 a1 2000 Both males and females carry food back to their single chick in their gular pouch In 2001 Karnovsky and colleagues 2003 con ducted atsea surveys for seabirds and found that birds breedingin Hornsund Fjord restrict their foraging to the cold Sorkapp current The majority of the that they captured to feed their chicks 93 were Calamity cope pods Furthermore C glamalzrmade up 76 of the biomass of the food they fed their chicks While many of the birds 87 did take some C nmmthuur they were taken in very low num bers 89 ofall prey items The NAOindexin 2001 was slightly negative In contrast in 2003 during apositive phase in the NAO birds at the same colony took high numbers of C nmanhzs my Iakubas 52 a1 2007 In that year 23 of the prey items delivered to chicks were C m manhqu Fig 20 The following year 2004 unusually col year with a negative phase ofthe NAO only 6 of the prey deliv ered to chicks were C nmmthuur Furthermore A 139 51410241115 Garimam wzkkzzzku Omrmu 1mmle were taken in low numbers by dovekies in 2001 and 2003 Karnovsky 52 a1 2003Jakubas a a1 2007 However in 2004 these iceassociated zooplankton were taken by a much higher per centage of birds feeding their chicks In 2004 68 of the birds took A glamalzx 35 ate 0 wzlkzzzku and 21 fed 0 12171774112 to their chicks Iakubas 52 a1 2007 2004 n m Modified from Kornovsky eml 2003 ondlokubos eml 2007 mi is 6 meals analyze Despite the positive phase of the NAG and the in ux of Atlantic water in 2003 the dovekies breeding that year were able to suc cessfully raise their chicks It seems that the birds were able to uffer the costs of feeding energetically inferior prey to their chicks by feeding them 14 times more often in a 24hour period than in 2004 Iakubas 52 a1 2007 Even though 2003 was considered a warm year the majority ofthe chick meals were still made up of the larger and more energyrich Cghmalzr The particular oceanographic conditions in which the reproductive success of these birds will be impacted are unknown Currently dovekies are the most abundant bird in the Arctic and possibly in the world Stempniewicz 2001 Declines in dovekies could indirectly impact the terrestrial Arctic system Reindeer geese and other herbi vores feed on the tundra fertilized by dovekies ying to and from their nests Stempniewirz 1990 estimated that dovekies at the Horn sund culuu 39 r 39 39 f km 2 per year Furthermore dovekies them selves are prey of Arctic foxes 1le ZagMur glaucous gulls Linux erbmeur and on ooca sion polar bears Urm mummy Kapel 1999 Stempniewicz 1995 2 06 FalkPetersen and colleagues 2006 predict with warmin d further declines in ice cover in the region C nmmthuur will become the dominant copepod species in the region E 3 304 C nmarchicus will be able to expand the range where it lives and reproduces because declines in ice will create phytoplankton bloom con ditions similar to what the Norwegian Sea to the south currently eXperiences The regions where C nmarchicus breeds off the Norwegian coast eXperience a regular early phytoplankton bloom of smallersized cells which support C nmarchicus They predict that the shift from C glacialis to C nmarchicus will lead to a food web where energy is transferred from C nmarchz cm to herring and ultimately to Minke whales Balamaptem acummmta instead of to dovekies FalkPetersen et a1 2006 Both exceptionally cold and warm years have been documented in the past eg Weslawski amp Adamski 1987 Weslawski amp Kwasniewski 1990 with increases in the den sities of C nmarchicus during the warm years see Fig 9 in Hop et a1 2002 Despite the in terannual variability in oceanographic condi tions in the study area there has been an over all warming trend of 1 C in the Sorkapp cur rent from 196571997 Blindheim et a1 2000 The temperature and thickness of the Atlantic water layer are highly correlated with positive phases of the NAO winter indeX although in some areas there is a lagged response to the NAO Mork amp Blindheim 2000 Schlichtholz amp Goszczko 2006 With increased advection of C nmarchicus into the Arctic and with the declines in sea ice it is likely there will be a shift in the pathways of energy ow to a very differ ent community of upper trophic predators Upper trophic predators that rely on the ad vection of prey into their foraging range are especially vulnerable to shifts in climate that result in changes in the timing strength and eXtent ofwater masses Dovekies with their re liance on the advection of large energyrich copepods of Arctic origin may be especially susceptible to shifm in climate that alter ei ther the production of prey at a distant loca tion or the movement of these prey to near their colonies If there is a mismatch between when they initiate breeding and when their prey is available they may eXperience reproductive Annals of the New York Academy of Sciences failure If Arctic conditions shift to a more bo real state dovekies may be forced to feed on lowerquality prey A sustained increase in the distribution and strength of North Atlantici derived water in the region will change both the amount and pathways ofenergy ux to up per trophic predators 32 The Southern Ocean 32 7 Phyfoplankfon Communify Response to Regional Warming As highlighted in sections 122 and 223 the WAP is undergoing the most rapid warm ing on Earth in the last few millennia This has impacted the eXtent and duration of sea ice in the region the stability of ice sheets and the retreat ofthe majority of glaciers in the re gion Cook et a1 2005 Dierssen and colleagues 2002 highlighted the effects of this signi cant seasonal glacial meltwater input on regional hy drography up to 100 km offshore Increased watercolumn stability and potential longer term impacts on seaice formation are likely secondary impacts of this increasing freshwa ter supply It was also suggested that meltwater could be a cause of limiting trace elements in the region and in fact phytoplankton biomass was related to the spatial and temporal re gions oflow salinity along the WAP Dierssen et a1 2002 The in uence of meltwater how ever could only eXplain about 30 of the variability in phytoplankton biomass Previous studies in the area show signi cant variabil ity in phytoplankton biomass related to water column stability Mitchell and Holm Hansen 1991 Moline 1998 Garibotti et al 2005a photoacclimation Moline amp Pr zelin 1996 Claustr et a 1997 Moline 1998 Moline amp Pr zelin 2000 andnutrient intrusions from the CDW onto shelf waters Prezelin et a1 2000 2004 Despite high interannual variability in phytoplankton biomass along the coastlines of the WAP and associated shelf a consistent and repeated pattern in phytoplankton community composition and succession has been observed along the coastline Moline eta 2004 Garibotti Molina et al Changes in Ice Dynamics and Polar Marine Ecosyslems Cryplnpllytes 2 a 2 g r 0 L5 1 5 0 5 10 Mean Daily Air Temperature C 1 39 ILIM f Figu Palmer Statron from 199 1 re 21 A Percent cryptopnytes as a tunctron of mea 171996 n 696 B Brvarrate plot at temperature and Gl1 E Salinity ppt E E 15 n aarly arr temperature at my Sample pomts rnarcate a gt50 e contttbutton to tne total pnytoplankton btomoss by aratorns cryptopnytes and pr mnestoplt tes a tPalrner Statron from 19 171 994 When domrnant Y cryptopnytes occuprea stgmftcontly lower soltmty water t an ertner aratorns or ptymnestor pnytes C Surface wotetsoltmty tor a sutv tne Antarctrc Penrnsula ltnes wnrte ltnes D Concurrent rntegratea water co eyDecembet1991throughlonuoty k tatorg 1992 tottons were occuprea every 20 m along tne lttstottcol LTER transect 1urnn contttbutton at ctyptop ytes to total pnytoplankton btomoss Frgures adopted from Molme et al 2004 1n color 1n Annas onltne 52 al 2005b Diatoms dominated spring phyto plankton populations each year However there was aconsistent transition from diatoms to pop ulations ofcryptophytes every summer Moline amp Prezelin 1996 Moline 5 a1 2004 The dom inance of cryptophytes was coincident with the occurrence oflowsalinity water which was as sociated with glacial meltwater input when air emperatures were above freezing Fig 21A Cryptophytes dominated algal biomass during meltwater events and their presence was con ned to the relatively hightemperaturelow n1ty water characteristic of the meltwater lens Fig 21B While con ned to surface wa ters the meltwater plume often extended to depths as great as 50 m Dierssen 52 a1 2002 In contrast diatoms and prymnesiophytes domi nated the phytoplankton communities in other physiochemical domains The annual domi ance of cryptophytes in lowsalinity waters occurs over a large area ranging in size from 11000 to 48000 km2 depending on the year and extended as far as a 100 km offshore Fig 21C D Garibotti 32 al 2005b This domi ance of crypto hytes within lowsalinity envi ronments is consistent with observations from other coastal areas around the Antarctic conti nent Kopczynska 1992 McMinn amp Hodgson 1993 Kang amp Lee 1995 Arrigo 52 a1 1998 Garibotti 52 a1 2003 The recurrent transition from diatoms to cryptophytes represents a fundamental de crease in the size class of the phytoplankton size from Bloomforming diatoms range in 306 ur a u N Ice Index 105 x km7 per month at 7 001 Annals of he New York Academy of Sciences Mean Air Temperature 0 Mean SalpKril Ratio Figure 22 Ratio of mean abundances of salps to Anmrcrrc krrH No 1 function ofthe regional senice rndex open crrcles and mean arr temperature for theAntorctic Peninsula close 157270 Lm Kopczynska 1992 Moline and Prezelin 1996 while the Antarctic crypto phytes have been measured microscopically at um McMinn amp Hodgson 1993 This size difference may be signi cant in driving the observed patterns in krill and salp abundance Fig 22 Koprzynska 1992 Hosie 52 a1 2000 Moline 5 a1 2004 Salps can efficiently graze food particles as small as 4 um in size Har bison amp McAlister 1979 Deibel 1985 Harbi son 52 a1 1986 Kremer amp Madin 1992 Madin amp Kremer 1995 but adult krill cannot The grazing efficiency of E mperba decreases sig ni cantly with particles lt20 um Meyer amp El Sayed1983Weber amp ElSayed 1985 Boyd 5 a1 1984 Quetin amp Ross 1985 therefore it is not surprising that grazing rates ofkrill on crypto phytes are negligible Haberman 52 a1 2003 the regional warming trend along the WAP is likely to continue with glacial melt water in uencing the largerscale hydrography the proportion of cryptophyte biomass to total phytoplankton biomass is expected to increase This indirect effect of climate change may be ecologically signi cant and would negatively impact the coastal food webs in the Antarctic A decrease in the phytoplankton size spectrum with warming and loss of sea ice would favor an increase in salps and would not favor krill circles Drawn from Table r 000 m4 as o m Loeb ercl 1997 through bottomup control Fig 22 As salps represent a relatively poor food source and an effective dead end in the Antarctic food web Fig 16 Dubischar 52 a1 2006 an alteration in the grazing assemblage would in turn lead to changes in the carbon transfer within the system Based on published grazing rates and efficiencies Moline and coworkers 2004 esti mated that the transition in the phytoplankton community dominated by diatoms to one dom inated by cryptophytes could lead to a 405 decrease in carbon transferred to higher trophic levels and an increase to the benthos In fact Gili and colleagues 2006 found that salps facil itated transfer ofcarbon to the benthic systems along the WAP These alterations in the food web if persistent will ultimately impact bio geochemical cycling in Antarctic coastal waters Walsh 52 a1 2001 Antarctic krill is central to the Antarctic marine food web and broadscale shifts in its spatial distribution during summer Loeb 52 a1 1997 Atkinson 52 a1 2004 would affect higher trophic levels including penguins see section 223 seals and whales The im pact on higher trophic levels may be especially signi th from a matchimismatch perspec tive as cryptophyte dominance occurs during u e months when feeding activities are at a maximum Laws 1985 Molina et ul Changes in Ice Dynamics and Polar Marine Ecosystems 4 Conclusion Sea ice is recognized as a fundamental com ponent of Earth s atmospheric and oceanic cli mate Recent trends in ice dynamics in the high latitudes show rising temperatures collapsing ice sheets and decreased seaice eXtent and in dicate that rapid environmental change is un der way with major changes in ocean chem istry Anderson amp Kaltin 2001 and productiv ity regimes Smetacek and Nicol 2005 These changes are revealing measurable and signi cant changes in individual organisms popula tions communities and ecosystems affecting energetics predatoriprey interactions repro ductive success phenology abundance diver sity and demographic shifts on large scales The largest uncertainty in forecasting the ef fects of climate change on ecosystems is in un derstanding how it will affect the nature of in teractions among species Winder amp Schindler 2004 Speci cally it will depend on whether climate disruptions of predatoriprey interac tions are maintained or whether species have the ability to adjust their phenology and spa tial demographics to climate change decreas ing the degree ofmismatch through changes at the population level In evolutionary history the persistence ofa given species has been largely governed by natural selection The rapid and dramatic changes along the Antarctic Penin sula and model simulation predicting the Arc tic being ice free in the summer by the latter halfofthe 21st century Walsh amp Timlin 2003 Johannessen et a1 2004 Overpeck et a 2006 suggest the time required for natural selection to occur is not available BerteauX and col leagues 2006 advocate quantitative criteria for assessing causal relationships between ecology and climate change which would help establish the different mechanistic links between the dy namics of populations and climate variability and help in predicting change Stenseth et a1 2002 Accurate predictions would be required for conservation and management of polar ma rine populations Simmonds amp Isaac 2007 It 307 should also be appreciated that under condi tions of climate change scienti c results and conclusions will need to be revisited frequently for example to rede ne phenology and popu lation boundaries Lombard et a1 2007 This identi es the need for time series studies on ap propriate spatial scales to resolve these changes Ducklow et a1 2007 The impacts of climate on ecosystems require interdisciplinary efforts in among others geophysics glaciologyg geol ogy chemistryg biogeochemistryg and numerous branches of biology March 2007 marked the beginning of the International Polar Year In an edito rial describing the event Walton 2007 sug gested a public information overload and a gen eral lack of public interest Since that opening event much has happened Fig 2 with cli mate change as a growing topic of public dis cussion see Kerr amp Kintisch 2007 Pennisi et a1 2007 Schiermeier 2007 A signi cant segment ofthe scienti c effort during the IPY is focused on climate and climate impacts Results from these studies during a year of dramatic changes in ice dynamics will provide more perspective and serve to increase attention to the compleX ityg scale and impacts of the changes occurring in polar marine ecosystems Acknowledgmenls We would like to thank the many people who help collect data in the eld for the work included here and recognize our sponsors Section 212 was supported by a grant from the World Wildlife Fund and from longterm funding by the Friends of Cooper Island to G Divoky Sections 213 and 311 were supported by NSFOPP awards 0612504 and 0301469 to N Karnovsky and by a Mellon Foundation postbaccalaureate grant to Z Brown Section 221 was supported in part by NSFOPP award 0336469 to T Frazer Data for section 223 are based on NSF OPP awards 7421374 7615350 8918324 9011927 9103429 9320115 9396281 308 9505596 9632763 9907950 9910095 0130525 0217282 0224727 and 0523261 to W Fraser Section 321 was supported by NSFOPP awards 9011927 and 9632763 to the Palmer LTER program Conflicls of Inleresl The authors declare no con icm of interest References Aagaard K amp EC Carmack 1989 The role of seaice and other fresh water in the Arctic circulation Gaa zys R55 94 14485714498 Ackley S at al 2003 Decadal decrease ofAntarctic sea ice extent inferred from halin record re 1 ired on the basis of historical and modern seaice records Palm R55 22 19725 Agnew DJ amp S Nicol 1996 Marine disturbancesi commercial shing 1n Faundallam fa Eaalaglaal Rae mm Wm af za Airmail Pmlnmla RM Ross EE Hofmann amp LB Quetin Eds 4177435 American Geophysical Union Washington DC Ainley D 2002 7725 Ad lla ngum Ballwallm af Climala Changa Columbia University Press New York p 310 Ainley DC at al 1986 Antarctic pack ice 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Sakshaug 1990 Polar Phytoplankton In Palm 055anagm 7y Pmi B Cl75ml517y Blalagy and G57 alagy W0 Smith Ed 4777525 Academic Press San Diego Stammerjohn SE amp RC Smith 1996 Spatial and tem poral variation of western Antarch Peninsula sea ice overage Faundallam fm E5alagl5al R555m57 W55l af 75 Aalm5ll5 Pmlmula In RM Ross EE Hofmann amp LB Quetin Eds 817104 American Geophysical Union Washington DC Stammerjohn SE 5t al 2008 Trends in Antarctic an nual seaice retreat and advance and their relation to EN SO and southern annular mode variability G5aj7lzy5 R55 113 doi10l0292007JC004269 Stammerjohn SE 5t al in press Seaice in the Palmer LTER region spatiotemporal variability from eco logical and climate change perspectives D5517 S551 k5 Stein R amp RM MacDonald Eds 2004 7775 07gmll5 Car l7an 25l5 in 75 A75ll5 055ml Springer Berlin Germany ISBN 3540011536 XIX 363 pp Stempniewicz L 1981 Breeding biology of the Little Auk Plaulu5 all5 in the Hornsund region SW Spitsber gen A5la Omit7d 18 1417165 Stempniewicz L 1990 Biomass of Dovekie Excreta in the vicinity of a breeding colony Calamal Wal57l7l7d5 l3 626 318 Stempniewicz L 1993 The polar bear 7505 70071117005 feeding in a seabird colony in FransJosefLand P0107 1amp51233736 Stempniewicz L 1995 Predatoryprey interactions be tween Glaucous gull 07155 15717571707505 and Little Auk A115 0115 in Spitsbergen A510 0775111501 29 1557170 Stempniewicz L 2001 A115 0115 L11115 Auk T175J015775010f 175 171705 0f 175 W5515775 P015075115 BWP Update Vol 5 Oxford University Press Oxford pp 1757201 Stempniewicz L 2006 Polar bear predatory behaviour toward molting Barnacle geese and nesting Glaucous gulls on Spitzbergen A75115 59 2477251 Stenhouse L 51 01 2004 Recoveries and survival rate of Ivory Gulls banded in Nunavut Canada 19717 1999 W01571717d5 27 4867492 Stenseth NC 51 01 2002 Ecological effects of climate uctuations S515055 297 129271296 amp HeideJizirgensen MP 2003 Tends and variability of seaice in Baf n Bay and Davis Strait 195372001 P0107 1amp5 22 11718 Stirling l 1997 The importance ofpolynyas ice edges and leads to marine mammals and birds M07 751 10 9721 Stirling l 2002 Polar Bears and Seals in the Eastern Beaufort Sea and Amundsen Gulf A synthesis of PopulationTrends and Ecological 39 39 Three Decades A75115 55 59776 Stirling l 5101 1999 Longterm Trends in the Population cology of Polar Bears in Western Hudson Bay in Relation to Climate Change A75115 52 2947306 Stirling l 5101 1977 7775 550105 0f117517010717507 U75u5 70077 11170155 01075g 1155 505515775 50051 0fHud5075 35y Cana 39an Wildlife Service Occasional Paper 53 Can Wildl Serv Ottawa 64 pp Stirling l 51 01 2007 Polar bear populations status in the northern beaufort sea Administrative Report United States Geological Survey Stirling I amp AE Derocher 1993 Possible impacts of climatic warming on polar bears A75115 46 2407245 Stirling I amp NJ Lunn 1997 Environmental uctuations in Arctic Marine Ecosystems as Re ected by Vari ability in Reproduction of Polar Bears and Ringed Seals ln E50105 0fA75115 E05170757057515 SJ Woodin amp M Marquiss Eds 1677181 Oxford Blackwell Science Ltd Stretch 51 01 1988 Foraging behaviour of Antarctic krill E15 i00510 5151757170 on seaice microalgae M07 E501 P70g S57 44 1317139 Stroeve JC 51 01 2005 Tracking the Arctic s shrink ing ice cover Another extreme September min imum in 2004 G50 g25 1amp5 L511 32 doi 1010292004GL021810 Stroeve JC 51 01 2007 Arctic seaice decline Faster than forecast 050171925 R55 L511 34 1109501 doi 1010292007GL029703 Annals of 1he New York Academy of Sciences Summerhayes VS amp CS Elton 1928 Further contri butions to the ecology of Spitsbergen E501 16 l 93268 Swerpel S amp M Zajaczkowski 1990 Physical environ ment of South Spitsbergen ln A1105 0f 175 M071755 F0000 0fS015175775 S171151757g575 RZ Klekowski ampJM Weslawski Eds 25741 Ossolineum Wroclaw Swerpel S 1985 The Hornsund Fiord Water Masses P011515 P0107 R55 6 475496 TremblayJ E 5101 2006 Trophic structure and pathways of biogenic 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3317 9 Werner ll amp Rs Gradingerl 2002 Underice amphipods in the Greenland Sea and Fram Strait Arctic envi ronmental controls and seasonal patterns below the pack ices Mm Biol 140 31773261 319 Werner ll ot at 2007 Seaice algae in Arctic pack ice during winters Polo Biol 30 1493715041 Weslawski amp R AdamskL 1987 Cold and warm o L L 1 Polish Polo ks 8 9571061 WeslawskiJlMl amp Sr Kwasniewskil 1990 Tho oohsoquonoos of o wo Procl Q47EMBS Symposium Aberbeen University Press pp 28172951 Weslawski ot a 1999 Summer feeding strategy of the little auk Alto alto from Bjornrzlya Barents Sea PoherioZ 21 12971341 Weslawski ot a 1994 Diet of ringed seals Phooo hts do in a fjord of West Svalbardl Arotto 47 1097 VVlnder Ml amp DlEl Schindler 2004 Climate change un cou les trophic interactions in an aquatic ecosystems Eoology 85 2100721061 VVlnther J Gl ot a 2004 Surface re ectance of seaice and underice irradiance in Kongsfjorden Svalbardl Polar Ros 23 11571181 Woehler ot a 2001 A Stotisttool 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