Rocky Intertidal, Coral Reeds, and Whales (Week 9)
Rocky Intertidal, Coral Reeds, and Whales (Week 9) BIOEE 1540
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This 10 page Class Notes was uploaded by Erica on Thursday October 29, 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 25 views.
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Date Created: 10/29/15
Rocky Intertidal Coral Reeds and Whales Rocky Intertidal Zona on Upper limit set by physical environment Lower limit set by biological interactions Competition Predation Vertical Zonation The hallmark of the intertidal zone Communities are divided into distinct bands or zones at characteristic heights Species are not randomly distributed throughout the intertidal zone but rather are arranged within relatively narrow vertical ranges The zones look like sharply divided belts easily distinguished by the colors of assemblage of organisms that live there Upper limit set by physical environment Lower limit set by biological interactions Competition Predation Physical Stresses often set upper limit to species distributions Stress Factors Desiccation Temperature Food Availability Wave Energy Salinity Dissolved Oxygen O EJ39IrPS JNt Biological Interactions often set lower limit to species distributions Biological Factors 1 Competition for Space Space on a rock is the valuable resource that is in short supply 2 Predation Species are not randomly distributed throughout the intertidal zone but rather are arranged within relatively narrow vertical ranges The zones look like sharply divided belts easily distinguished by the colors of assemblage of organisms that live there Cause of Zonation Barnacle Example 1 The upper limit of both species is determined by emersion larvar that settle too high in the intertidal dry out and die physical factor a Little grey barnacles can tolerate drying better than rock barnacles so they settle higher in the intertidal 2 At lower levels where the rock barnacles can survive the rock barnacle out competes the little grey barnacle for space biological factor and this sets the lower limit for the little grey barnacle 3 The lowest limit of the adult rock barnacles is determined by competition for mussels and predation by whelks or sea stars biological factors Species Diversity within Rocky Intertidal Communities Intermediate Disturbance Physical Disturbance can regulate species diversity within a community 1 Physical disturbance can open up gaps or patches in the rocky intertidal ex wave energy from storms 2 Intermediate Disturbance Hypothesis disturbance maximizes species diversity by periodically removing competitively dominant species amp allowing less competitive species to reestablish themselves Too much disturbance 9 keeps the rock bare with few species Too little disturbance 9 dominant competitor for space to take over and form a monoculture Starfish predation9high diversity Sets lower limits of mussel distributions in rocky intertidal Leads to higher species diversity within a rocky intertidal community 0 Mussels can out compete most other organisms for space 0 Pisaster Starfish predation sets the lower limit to mussels and below this lower limit other species can settle in o The removal or Pisaster allows mussels to take over 9 decrease in the community s species diversity just mussels remain Species are not randomly distributed throughout the intertidal zone but rather are arranged within relatively narrow vertical ranges The zones look like sharply divided belts easily distinguished by the colors of assemblage of organisms that live there Keystone Species Species that have effects on their communities that are proportionately much greater than their abundance would suggest Pisaster is a classic type of keystone predator that strongly in uences community diversity Trophic Cascading Effects Sea Otters Kelp Forest Example Sea Otters eat sea urchins Sea urchins are herbivores that eat tiny young kelp Removal of sea otters allows sea urchins to grow to high abundance Low abundance of sea otters 9 high abundance of sea urchins amp low abundance of kelp forests 9053 Coral Reets Coral Anatomy the process of building a calcium carbonate reef structure is a very slow process lt 1mm per year to about 20mm per year Coral Energetics Zooxanthellae are chlorophyllcontaining algal symbionts that live in the tissue of the coral polyp Corals receive 0 90 of their overall nutrition from photosyntheticderived oroducts Limits to Coral Growth 1 Temperature 0 o o 2 Sunlight O 0 Limits coral growth to tropical latitudes Optimal 2628 degrees Celsius Restricted 1836 degrees Celsius Limits coral growth to a depth range extending from the ocean surface down to a maximum of about 25 m Light required for zooxanthellae to photosynthesize 3 Space to Grow O O 4 Predation Because corals rely on the photosynthesis of Zooxanthellae they have a depth limit set by light levels below which they cannot grow effectively This limit is typically about 25m C0ral ReefFormation A new island forms and a fringing reef develops in shallow sunlit waters cose to shore of the island The island slowly sinks with age and the coral slowly upward by secreting its calcium carbonate support structure layerby layer 0 Barrier reef At time point the entire island is submerged and all that s left is the reef o Coral atoll If the island sinks too fast or sea level rises too fast 9 reef cannot keep up with its upward growth 9 reef then stops growing 0 Drowned reefs Corals compete for space Competing with other corals o Sweeper tentacles Competing with macroalgae o The competitive advantage for taking over space is shifted in favor of microalgae when nutrients from agricultural activities run off the coast and onto coral reefs Predati0n by Crown of Thorns Star sh Acanthaster This starfish is an important predator of corals One of the main sources of coral mortality Eutrophic conditions increase phytoplankton abundance that enhances the growth of the Starfish larvae 9 to the large increase in abundance of adults and high coral mortality C0ral Bleaching It s the zooxanthellae algae that give gorals all of their natural vibrant colors Coral bleaching is the name given the an event where corals expel their symbiotic zooxanthellae algae due to environmental stress such as unusually warm water Corals can recover and regain their zooxanthellae if the stress is small or shortlived Coral death follows if the stress is extreme or prolonged Corals are extremely sensitive to rises in sea temperature 1 degree Celsius above normal for just a few weeks can result In bleaching gtquotThe developing 2015 El Ni o event will bring wide spread cloral bleaching amp death The global average loss of coral is now at about 27 0verall Coral reefs around the world are in rapid decline Coral reefs are degrading at an increasing pace because of the effects of both localscale stressors due to pollution and globalscale stressors due to planet warming amp acidification of the ocean Localscale stressors should be minimized to offset increasing globalscale stressors Managing local water quality conditions to alleviate the pressure from globalscale stresses is now a top priority Whales Coral Anatomy the process of building a calcium carbonate reef structure is a very slow process lt 1mm per year to about 20mm per year Whale Evolution 1 Pakicetus 53 million years ago after dinosaur age 0 Dogwolf with hoofed feat and long thick tale 0 Special ear bone feature diagnosed for cetaceans and found in no species other than whales 2 Ambulocetus walking whalequot 5049 million years ago 0 Early cetacean that could walk and swim 3 Rodhocetus 4647 million years ago 0 Could still walk on land but not well 4 Dorudon 4036 million years ago 0 5 meters in length o Carnivore 0 Couldn t go on land 5 Basilosaurus 4037 million years ago 0 2 feet long 0 Very small hind legs 0 Equipped with cone shaped teeth in front amp triangular teeth in back Evolution from Toothed Whales to Baleen Whales All Baleen Whales Mysticetes are large filterfeeders Used differently among species 0 Gulpfeeding o Skimfeeding 0 Bottom plowing The first members appeared about 35 million years ago 0 May have resulted from environmental amp physical changes in the oceans Feeding Modes Baleen whales feed by gulping large quantities of seawater and then squeezing the water through the baleen quotfilterquot to retain krill and small fish V0calizati0ns 1 Odontocetes toothed whales Produce rapid bursts of clicks and whistles Do not make the long lowfrequency sounds known as the whale song Single clicks are generally used for echolocation Collections of clicks and whistles are used for communication The multiple sounds themselves are produced by passing air through a structure in the head rater like the human nasal passage 2 Odontocetes toothed whales Often make the long lowfrequency sounds known as the whale song Have a larynx that appears to play a role in sound production but it lacks vocal cords and scientists remain uncertain as to the exact mechanism Mysticete Vocalization Sexual Selection or Navigation The complex and haunting sounds of the humpback Whale are believed to be primarily used in sexual selection during mating season but the simpler sounds of other whales have a yearround use 0 Toothed whales are capable of using echolocation to detect size amp nature but this hasn t been demonstrated in Baleen Whales 0 Simple sounds may play a role in navigation because there is poor visibility in the oceans and sound travels well in water 0 Spectograms Used to visualize the whale vocalization 0 Time on xaxis 0 Frequency on yaxis o Loudness is denoted by brighter colors Frequency Christopher Clark Cornell Lab of Ornithology Whaling Whaling 0 Sources of Anthropogenic Sound I Commercial Shipping Engine amp propeller noise I Naval Operations Low frequency active sonar I Oil Exploration Seismic surveys with explosive air guns cannons 0 Repeated every 10 seconds 24 hours amp weeks at a time 0 Noise Pollution I Acoustic Habitatquot no different than spatial habitat and must be preserved I quotNoise Pollutionquot every bit as destructive as other forms of more familiar marine pollution oil plastic etc This starfish is an important predator of corals One of the main sources of coral mortality Eutrophic conditions increase phytoplankton abundance that enhances the growth of the Starfish larvae 9 to the large increase in abundance of adults and high coral mortality International Convention for the Regulation of Whaling ICRW International Whaling Commission IWC was set up under the terms of the ICRW to make decisions on quota levels based on findings from the Scientific Committee of the IWC Members of the IWC voted on July 23 1982 to apply a moratorium to all commercial whaling beginning in 1985 Japan 0 O Continues to whale by claiming its whaling operation is now for scientific purposes The IWC allows lethal scientific whaling but only when it addresses questions vital to management Numbers vary each year but on average it is close to 1000 Minke notendangered 50 Fin endangered 50 Humpback endangered and 5 Sperm endangered whales each year Norway 0 Registered an objection when the 1982 IWC whaling moratorium was signed amp was not bound by it 1993 Norway decided to exercise its reservation and resumed domestic commercial whaling They now take about 600 Minke notendangered whales each year Iceland 0 Issued licenses in October 2006 for a commercial whale hunt in addition to its continuing hunt for scientific purposes Iceland has an exemption to the moratorium through the reservation it made in 2002 They take about 150 Fin endangered and 200 Minke notendangered whales each year