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This 7 page Class Notes was uploaded by Sidnee Notetaker on Wednesday October 21, 2015. The Class Notes belongs to BIOEE 1540 at Cornell University taught by Bruce C. Monger in Fall 2015. Since its upload, it has received 16 views.
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Date Created: 10/21/15
Microbial Processes Wednesday October 21 2015 556 PM I Part 1 A Definition 1 Oligotrophic Pelagic environment water column that has naturally very low plant nutrient concentrations I the vast subtropical gyres are oligotrophic 2 Eutrophic Pelagic environment water column that has naturally high plant nutrient concentrations I coastal upwelling zones are eutrophic B As a general rule the preferred prey size is approximately 110 of consumer size 1 Other than chlorophyll size determines almost everything about an organism s role in the community of pelagic organisms a It determines who it will eat all organisms 110 its own size b It determines who will eat it all organisms 10 times bigger than it Marine Food Webs are Said to be Strongly SizeStructured 2 Simplified Pelagic Food Chain Conceptualization 3 Optimal Prey Size 110 of Pelagic Animals is a Valid General Rule for Even the Smallest Pelagic Organisms Protozoans and Bacteria CILIMfiEii PHDiime w 1 Q a a E 3i L 39 V VHF Im A Ear 39 V g 5555 inn If B 391 7 at inquot IE i m 53 IIm 7 l3quot lII l39 I 1 39 Q G 1 quoth lfll 13 l c l R Fll 39i l W ad Foil H i quot h l n i r g r i H as 3 d 5 E g a g m 1 5 n all 11 Hi 3912 Eta55 Pr 3 C Traditional Food Chain Concept early1970 s 1 Note organisms are placed into a given Trophic Level based on Autotroph versus Heterotrophic ie chlorophyll versus no chlorophyll and on the organism s size Microbial Processes Page 1 4 39ino Heterotrophs 2x103 1339 2x101 Ir 8 gt hot flagellatos I i g k lKCJ 20 gt hat bacteria 02 auto bacterla 2 Traditional Bacterial Concentrations Estimated from Transmission Light Microscopy and CulturePlate Colony Counts Bacterial Concentration lozml I00 Depth From SHrdrup ct al I946 3 Use of Epifluorescent Microscopy and Fluorescent DNA Stains Became Widespread Between 1975 and 1985 a Dramatically increased estimates of bacterial concentrations in the ocean b Also allowed easy distinction between autotrophic and heterotrophic flagellate cells ie chlorophyll containing or chlorophyll lacking 4 Bacterial Concentrations Before Red Fill and After Blue Fill the Introduction of Epifluorescent Microscopy Bacterial Concentration Iosn 0 2 4 6 8 I0 50 5 g l00 Microbial Processes Page 2 a New view of marine food webs recognizes the importance of high bacterial biomass and a large fraction of nanoflagellates 220micron diameter cells that are heterotrophic consumers of bacteria Heterotrophic bacteria are growing on dissolved organic matter sugars amino acids etc released from phytoplankton by steady leakage sudden cell senescence or sloppy feeding by zooplankton The term quotMicrobial Loop is coined by Azam et al 1983 to describe the role that microbes play in the marine ecosystem carbon cycle 5 Discovery of an Important New BacteriaSized Autotroph a c 6 Simpl In 1988 Sally Chisholm and Others Published a Paper Describing the Presence of a New Type of Very Small Autotroph that is Present in High Abundance Especially in Oligotrophic Regions The Discovery was Made using a New Technique called Analytical Flow Cytometry This Important New Autotroph Came to be Known as Prochlorococcus e Diagram of Flow Cytometric Method 7 Prochlorococcus Abundance a Prochlorococcus abundance in the oligotrophic openocean is similar in magnitude to the abundance of heterotrophic bacteria Microbial Processes Page 3 Roughly 13 of all bacteria in the oligotrophic openocean is autotrophic Prochlorococcus 8 New View 1990 s of Marine Food Webs that Recognizes the Importance of Prochlorococcus Dimlwdl Iganic Matter 1 9 In oligotrophic low nutrient openocean environments the growth advantage goes to the smallest phytoplankton cells which are now recognized to be represented mainly by Prochlorococcus a Prochlorococcus is the main contributor to primary production in openocean environments b Altogether Prochlorococcus singlehandedly contributes more than a quarter of total ocean primary production with the remainder being contributed by hundreds of other phytoplankton groups 10 Relative Importance of Prochlorococcus and Heterotrophic Bacteria in Oligotrophic Systems Modi ed rum Camping rut in I 1994 Team Carbon lg If m39 I II Part2 A The Role of Microbes in Carbon Cycling in the Ocean The Biological Carbon Pump 1 Carbon Cycling and the Biological Carbon Pump Microbial Processes Page 4 E39ullir plhic Conditions Uligntmpllic Condititms El When the dominant phytoplankton cells are large the dominant grazers are large and their large fecal material easily sinks to the deep ocean taking organic carbon down with it this forms an efficient biological carbon pump The opposite is true when the dominant phytoplankton is small and grazers are small and fecal material is so small it cannot easily sink and the particulate carbon is instead respired back to C02 and overall the biological pump is inefficient 2 What is the expected efficiency of the Biological Carbon Pump for Costal Upwelling Zones CI The carbon pump is very efficient in coastal upwelling zones B Role of Microbes in Nitrogen Cycling in Marine Ecosystems 1 All living things have a roughly fixed ratio of major elements in their cells carbon to nitrogen to phosphorous to oxygen etc which is often referred to a fixed chemical stoichiometry 2 Because of this fixed chemical stoichometry in all living matter the pattern of recycling and export to the deep ocean for all of major elements will look quite similar For example a Where you find carbon being recycled you also find nitrogen being proportionally recycled b And where you find carbon being exported to the deep ocean you also find nitrogen being proportionally exported to the deep ocean 3 Nitrogen Cycling the concept of New amp Recycled Primary Production Total Primary Production Recycled New Primary Production Upper Ocean 1 W Primary quotquot39 production uses no Ammonia We generated by animal quot17 excretion in the upper ocean for its nitrogen source a 2 New Primary T Production uses Nitrate N03 from the deep ocean for its nitrogen source NH4 Ammonia N03 Nitrate Y It a 1l0I L 1 Nitrogen Uptake Deep Ocean Microbial Processes Page 5 Eutrlphic Oligotmphie ljppel Emmi ljppigI imam me man a Eutrophic high nutrients conditions are dominated by large cell and most of the primary production is New production b Oligotrophic low nutrients conditions are dominated by small cells and most ofthe primary production is Recycled production c NOTE New Production is the portion of total primary production that is available to sink out of the upper water column and into the deep ocean C Evolving Concepts of Microbial Food Webs 1 Iron Cycling in HNLC Regions l ppcr ccun IRJ Napmu hum lit ukqu quotum um nlnmpxhrnr Jqnlun u ulna up D JIHHHUIDh In Kqummlnl I lmlwIun I llhu n fur lk h 33 5 Station Aloha ab 5 2 5 39 8 S 8 y 81L1111111111111111111111111111111111 0 30 s 6039E EYE 120 150 13039 150M120 N 90quot m m 039 Longitude m 0 5 10 5 20 25 Nitrate mcrornolar 3 Time Series of NP Ratio for Total Dissolved Suspended Particulates in the North Pacific Subtropical Gyre from Karl 1999 Showing a shift to Phosphorous Limitation Iiiiiiiiillli IIllhliliiiIillFllililsiiliivi lllldilvlili Busnaioeo FWELES 5 i i ll l 7 ill 1 rill Microbial Processes Page 6 iiifliil39l39lllliililllllilllliIm41 JngiiLimnisliul Stream PWELES lmolzmoli r l l l v l l l l K g l l 539 g l 139 39 3 l l 39 l g w 1 1 I cl 2U 5 m l 5 it v y t 39 w quotH j 1 5 may 3 r 39 5 a A I gt L 1 g 7 39 g 1 j a o 2 3 i a L m I I w 5 g i Hallie iiillll lllIlLLIlllmlll1lll lllmlllllllijililiillillllI MlJDJEJ DJAJDJEJJ J J J 39JAJDellJ39DJ JAJD 1W1 39ll Sampling lute 4 Phos horousC lin Ll puper llillman in the ni organic organic phosphorous Inorganic Phosphate 5 Nitrogen Fixation lppcrUuun Ioo O 0 un rlnuun ilrumn 1 9 Human lI k I I llutvuphl O 0quot oln vu u Iquot hu 1 mumm I mm l cumin lulu up in quot Iluhylruph fnr rmll l Y lkcp ccan 6 Role of Microbes in the Cycling of Other Chemical Elements a Typically oceanographers want to study the cycling of the element that is limiting the growth of phytoplankton in the region of interest i So for the Southern Ocean they study iron cycling ii And in the North Pacific Subtropical Gyre north of Hawaii they study the cycling of phosphorous iii But for a great many places in the world ocean nitrogen is limiting and nitrogen cycling is studied Microbial Processes Page 7
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