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13 ecosystems2 1

  1. 1. Announcements Mar. 9, 2011 March 8 @ 12 noon University YMCA | Latzer Hall   The Sustainable Student Farm: Learn, Grow Food, Eat It   Zack Grant, Farm Manager/Project Coordinator  
  2. 2. Lecture Objectives: <ul><li>Types of Ecosystems II </li></ul><ul><li>Learn the characteristics of the major biomes - aquatic systems </li></ul><ul><li>Learn about human impacts on freshwater and marine systems </li></ul>
  3. 3. Aquatic Biomes <ul><li>Occupy the largest part of the biosphere </li></ul><ul><ul><li>- two thirds of the Earth is covered by oceans </li></ul></ul><ul><li>Marine algae and photosynthetic bacteria produce large portion of world ’s oxygen and consume large amounts of CO 2 </li></ul><ul><li>Differ by salt concentration: </li></ul><ul><ul><li>- freshwater </li></ul></ul><ul><ul><li>- saline </li></ul></ul>
  4. 4. Aquatic Biomes <ul><li>Aquatic biomes primarily influenced by: </li></ul><ul><ul><li>Light penetration </li></ul></ul><ul><ul><li>Type of bottom substrate </li></ul></ul><ul><ul><li>Water temperature </li></ul></ul><ul><ul><li>Dissolved materials </li></ul></ul>
  5. 6. Human Impacts on Marine Systems <ul><li>Many threats to words oceans </li></ul><ul><li>We will focus on: </li></ul><ul><ul><li>Overfishing </li></ul></ul><ul><ul><li>Aquaculture </li></ul></ul><ul><ul><li>Coral reefs </li></ul></ul>
  6. 7. Pelagic Marine <ul><li>Pelagic - open water environment </li></ul><ul><ul><li>Euphotic zone where all photosynthesis occurs </li></ul></ul><ul><ul><ul><li>Upper layer where suns rays penetrate </li></ul></ul></ul><ul><ul><li>Primary producers are phytoplankton </li></ul></ul><ul><ul><ul><li>Small, microscopic algae and bacteria </li></ul></ul></ul><ul><ul><ul><li>Nutrient concentration extremely important in determining productivity </li></ul></ul></ul><ul><ul><li>Phytoplankton consumed by zooplankton, consumed by crustaceans and fish, consumed by larger fish </li></ul></ul>
  7. 8. Biomes: Pelagic Marine (cont.)
  8. 9. Benthic Marine <ul><li>Benthic - bottom </li></ul><ul><ul><li>Several types: coral reefs, mangrove swamps, abyssal </li></ul></ul><ul><ul><li>Type determined by substrate, temperature and depth </li></ul></ul>
  9. 10. Benthic Marine <ul><ul><li>Coral reefs </li></ul></ul><ul><ul><ul><li>Require shallow, clear, warm water </li></ul></ul></ul><ul><ul><ul><li>Coral is a sessile animal that excretes a hard, exoskeleton </li></ul></ul></ul><ul><ul><ul><li>Animals have symbiotic relationship with algae </li></ul></ul></ul><ul><ul><ul><li>One of most diverse and productive biomes on earth </li></ul></ul></ul><ul><ul><ul><li>Protect coasts from storms, uptake carbon </li></ul></ul></ul>
  10. 11. Threats to Coral Reefs <ul><li>Most threatened marine habitat </li></ul><ul><li>1. Trawling and dynamite fishing - breaks up reefs </li></ul><ul><li>2. “Bleaching” - death/loss of algae </li></ul><ul><ul><li>3. Runoff – pollutants </li></ul></ul><ul><ul><li>4. Aquarium industry </li></ul></ul><ul><ul><li>5. Global warming - corals need shallow water </li></ul></ul>
  11. 12. Benthic Marine <ul><ul><li>Mangrove swamps </li></ul></ul><ul><ul><ul><li>Occur in warm, shoreline areas, with low wave action </li></ul></ul></ul><ul><ul><ul><li>Important nursery area for shrimp, fish </li></ul></ul></ul>
  12. 13. Benthic Marine <ul><ul><li>Abyssal ecosystem </li></ul></ul><ul><ul><ul><li>Deep, no light; depend on organic matter from above </li></ul></ul></ul>
  13. 14. Oceanic Fisheries Worldwide, 25% of animal protein 70% of world ’s marine fisheries are overexploited or in danger of becoming overexploited
  14. 15. Oceanic Fisheries <ul><li>Number of fish caught rose steadily until 1990 ’s, but per capita number caught decreased </li></ul><ul><ul><li>Human population growing faster than increase in catch </li></ul></ul><ul><li>Leads to increased demand and overfishing </li></ul><ul><ul><li>many species commercially extinct - no longer economically profitable to harvest </li></ul></ul>
  15. 16. Sustainable harvest <ul><li>Ideal strategy : harvest population to maximize growth rate </li></ul><ul><ul><li>determines how quickly fish can be removed, while still maintaining healthy stock </li></ul></ul><ul><ul><li>keep population at half carrying capacity (too little or too much harvest, population grows slowly) </li></ul></ul>Most fisheries harvest too much!
  16. 18. Why does overfishing occur? <ul><li>Economics - Tragedy of the Commons </li></ul><ul><ul><li>Each group tries to maximize individual returns at expense of common resource </li></ul></ul><ul><li>Quota problems </li></ul><ul><ul><li>Often a fixed number, not percentage </li></ul></ul><ul><ul><li>(Harvesting constant number of decreasing population leads to severe impacts) </li></ul></ul><ul><li>Technological “Improvements” </li></ul>
  17. 19. Overfishing Example: Bluefin Tuna <ul><li>Large, wide ranging, fast animal </li></ul><ul><ul><li>Grows to 1500 lbs. </li></ul></ul><ul><ul><li>Swims up to 50 mph </li></ul></ul><ul><ul><li>Can migrate across oceans </li></ul></ul><ul><li>One of most valuable and over-exploited fish </li></ul><ul><ul><li>Single fish sold for $172,000 in Tokyo fish market auction - sashimi </li></ul></ul><ul><ul><li>Adult population declined 90% since 1975 </li></ul></ul><ul><ul><ul><li>250,000 to about 22,000 </li></ul></ul></ul>
  18. 20. Overfishing: Bluefin Tuna
  19. 21. Overfishing: Bluefin Tuna <ul><li>International Commission for the Conservation of Atlantic Tunas (ICCAT) responsible for management </li></ul><ul><ul><li>Manages tunas and tuna-like species (marlins, swordfish) </li></ul></ul><ul><ul><li>Supposed to manage for maximum sustainable yield </li></ul></ul><ul><li>Has scientific committee </li></ul><ul><ul><li>Compile catch statistics and models population trends </li></ul></ul>
  20. 22. Overfishing: Bluefin Tuna <ul><li>Commission ’s managers repeatedly ignored scientists’ advice </li></ul><ul><ul><li>e.g., 1981 own scientific committee concluded Atlantic tuna population depleted, quotas should be set close to zero </li></ul></ul><ul><li>Set 1160 metric ton quota for “scientific study” </li></ul>
  21. 23. Overfishing: Bluefin Tuna Population continued to decline, but doubled quota Early 1990s - Sweden wanted to list bluefin on CITES (Convention on International Trade in Endangered Species)
  22. 24. Overfishing: Bluefin Tuna <ul><li>Lobbying by U.S., Canada, and Japan, forced Sweden to accept compromise </li></ul><ul><ul><li>50% reduction in catch </li></ul></ul><ul><li>Why did efforts fail? </li></ul><ul><ul><li>1. Lack of commitment by Commission </li></ul></ul><ul><ul><ul><li>conflicts of interest - some work for seafood industry </li></ul></ul></ul><ul><ul><li>2. Quota problem - number not percent </li></ul></ul><ul><ul><li>3. Lack of international support </li></ul></ul><ul><ul><li>4. Non-member nations </li></ul></ul>
  23. 25. Tuna ban 'justified' by science By Richard Black 29 October 2009 Banning trade in Atlantic bluefin tuna is justified by the extent of their decline, an analysis by scientists advising fisheries regulators suggests. The International Commission for the Conservation of Atlantic Tunas' (ICCAT) advisers said stocks are probably less than 15% of their original size. For a number of years, ICCAT has set quotas higher than scientists' recommendations. The pressure this puts on stocks has been compounded by illegal fishing for this valuable species, which according to some estimates adds 30% to the official quota.
  24. 26. Bluefin tuna trade ban gains European Union backing By Richard Black 10 March 2010 EU nations have decided to support a ban on international trade in Atlantic bluefin tuna until stocks recover. The bloc has agreed to back a motion for a ban during next week's meeting of the Convention on International Trade in Endangered Species (CITES). The US has already given its support, but Japan - where most bluefin is eaten - may opt out of CITES controls. The EU is backing exemptions for traditional fishers, and deferring the ban for a year.
  25. 27. Bluefin tuna ban proposal meets rejection By Richard Black 18 March 2010 A proposal to ban international trade in Atlantic bluefin tuna, which is a sushi mainstay in Japan, has been rejected by a UN wildlife meeting. Thursday's decision occurred after Japan, Canada and many poor nations opposed the measure on the grounds it would devastate fishing economies. Stocks have fallen by about 85% since the industrial fishing era began. &quot;Welcome to the strange world of globalisation.&quot;
  26. 28. Is Aquaculture the answer? Aquaculture - breeding and raising of fish and shellfish for food Rapidly increasing industry Provides 1/4 world ’s marine fisheries
  27. 29. Aquaculture <ul><li>Problems </li></ul><ul><ul><li>1. Still depletes natural fish populations </li></ul></ul><ul><ul><ul><li>Feeds often include fishmeal from wild populations </li></ul></ul></ul><ul><ul><ul><ul><li>especially problematic for carnivores fish (e.g. salmon) </li></ul></ul></ul></ul><ul><ul><li>2. Fish wastes - aquatic pollution, disease </li></ul></ul><ul><ul><li>3. Genetic diversity </li></ul></ul><ul><ul><ul><li>raised fish escape and breed with wild fish </li></ul></ul></ul><ul><ul><li>4. Can still be bycatch </li></ul></ul><ul><ul><li>5. Habitat destruction - loss of mangroves, coastal wetlands habitats </li></ul></ul>
  28. 30. GMO Salmon GMO fish grow faster and need less food Concern over possible escape from aquaculture “ Trojan gene affect” – Muir & Howard, 1999; Howard et al. 2004
  29. 32. Freshwater Ecosystems <ul><li>Overharvesting of resources </li></ul><ul><li>Habitat Modification </li></ul><ul><ul><li>Channelization </li></ul></ul><ul><ul><li>Dams </li></ul></ul><ul><ul><li>Draining wetlands </li></ul></ul><ul><ul><li>Changes in terrestrial landscape </li></ul></ul><ul><li>Invasive Species (e.g., zebra mussel, lamprey) </li></ul><ul><li>Pollution </li></ul><ul><li> (will discuss invasions and pollution in later lectures) </li></ul>
  30. 33. Estuary <ul><li>Shallow, partly enclosed area where salinity changes with tides </li></ul><ul><li>Very productive </li></ul><ul><ul><li>Nutrients from rivers </li></ul></ul><ul><ul><li>Light penetration </li></ul></ul><ul><li>Important nursery areas for crustaceans and fish </li></ul>
  31. 34. Freshwater - lakes <ul><li>Three main habitats: </li></ul><ul><ul><li>Littoral Zone : shallow areas with rooted submergent and emergent plants </li></ul></ul><ul><ul><li>Pelagic Zone : deeper areas of open water </li></ul></ul><ul><ul><li>Benthic Zone : Bottom </li></ul></ul>
  32. 35. Rivers and Streams <ul><li>Characterized by running water </li></ul><ul><ul><li>Attached algae main producer </li></ul></ul><ul><ul><li>Many nutrients come from input of terrestrial organic matter </li></ul></ul><ul><ul><li>In large rivers, floodplain important source of nutrients, spawning habitat for fish </li></ul></ul>
  33. 37. Channelization <ul><li>the dredging and straightening of stream channels </li></ul><ul><li>Why? </li></ul><ul><ul><li>Divert water for irrigation </li></ul></ul><ul><ul><li>Drain fields for agriculture </li></ul></ul><ul><ul><li>Increase “usable” land </li></ul></ul><ul><ul><li>Prevent flooding </li></ul></ul>Kissimmee River, FL 1961 Present
  34. 38. Problems with Channelization <ul><ul><li>Altered flow regimes </li></ul></ul><ul><ul><ul><li>Many species not adapted to different flows </li></ul></ul></ul><ul><ul><li>Loss of habitat </li></ul></ul><ul><ul><li>Reduces habitat complexity </li></ul></ul><ul><ul><ul><li>Total stream area </li></ul></ul></ul><ul><ul><ul><li>Floodplains </li></ul></ul></ul>
  35. 39. Dams and stream modifications <ul><li>Long history of modifying rivers </li></ul><ul><ul><li>Egypt had irrigation ditches by 3200 B.C. and dams by 2760 B.C. </li></ul></ul><ul><li>Dams built per year steadily increased from around 1800 to a peak in the 1970 ’s. </li></ul>
  36. 40. Dams and stream modifications 75,000 dams over 2m tall, plus 2.5 million smaller dams in the U.S. alone
  37. 41. Effects of Dams <ul><li>Benefits: </li></ul><ul><ul><li>Water supply </li></ul></ul><ul><ul><li>Navigation </li></ul></ul><ul><ul><li>Hydropower </li></ul></ul><ul><ul><li>Flood Control </li></ul></ul><ul><ul><ul><li>Decreased frequency, but increased severity </li></ul></ul></ul>
  38. 42. Physical Effects of Dams <ul><li>Alterations of flow </li></ul><ul><ul><li>Prevents movement of sediment, nutrients downstream </li></ul></ul><ul><ul><li>Slower flows upstream </li></ul></ul><ul><ul><ul><li>leads to settling of sediment </li></ul></ul></ul><ul><ul><ul><li>reservoirs can fill by as much as 80% in 12 years </li></ul></ul></ul><ul><ul><li>More unpredictable flows downstream </li></ul></ul><ul><ul><li>Disturbs normal flood-pulse in spring </li></ul></ul><ul><ul><ul><li>Interchange of nutrients between river and floodplains </li></ul></ul></ul>
  39. 43. Biological Effects of Dams <ul><li>Interrupts fish migration (e.g., salmon) </li></ul><ul><ul><li>Fish ladders can help </li></ul></ul><ul><ul><li>Still can have 10-20% fish loss during outmigration </li></ul></ul>
  40. 44. Human Health Effects of Dams Aswan Dam, Egypt – completed in 1970 Schistosomiasis (Bilharzia ) Parasite passes from humans to snails to humans Irrigation from lake provided more habitat for snails
  41. 45. Wetlands <ul><li>Transitional habitats between aquatic and terrestrial environments, where water table is at or near the surface </li></ul><ul><ul><li>Includes marshes, swamps, bogs, estuaries, temporary ponds, etc. </li></ul></ul><ul><li>Estimated loss of 53% of total wetlands in U.S. </li></ul><ul><ul><li>9.2 million acres lost between 1950 ’s-1970’s </li></ul></ul><ul><ul><li>2.6 million acres lost between 1970 ’2-1980’s </li></ul></ul><ul><ul><li>current loss of 124,000 acres per year </li></ul></ul>
  42. 47. Wetland Loss <ul><li>Wetlands provide important ecosystem services </li></ul><ul><ul><li>1. Mitigate flooding </li></ul></ul><ul><ul><li>2. Retention of sediments, nutrients, pollutants </li></ul></ul><ul><ul><ul><li>Natural sewage treatment plants </li></ul></ul></ul><ul><ul><li>3. Wildlife habitat </li></ul></ul><ul><ul><ul><li>20% of threatened and endangered species associated with wetlands </li></ul></ul></ul>
  43. 48. Audubon Society Seafood Ratings <ul><li>Green – abundant, well managed </li></ul><ul><ul><li>Farmed mussels and clams </li></ul></ul><ul><ul><li>Alaska salmon </li></ul></ul><ul><ul><li>Troll caught Mahimahi </li></ul></ul><ul><ul><li>U.S. farmed Tilapia </li></ul></ul><ul><ul><li>Pole/troll caught yellowfin, bigeye, albacore tuna </li></ul></ul><ul><li>Yellow – some concern over status. </li></ul><ul><ul><li>Longline caught Mahimahi </li></ul></ul><ul><ul><li>Pacific cod </li></ul></ul><ul><ul><li>Rainbow trout </li></ul></ul><ul><ul><li>Maine lobster </li></ul></ul><ul><ul><li>Squid (calamari) </li></ul></ul><ul><ul><li>Canned tuna </li></ul></ul><ul><li>Red – severe overfishing, poor management </li></ul><ul><ul><li>Atlantic cod </li></ul></ul><ul><ul><li>Shrimp </li></ul></ul><ul><ul><li>Atlantic flounders and soles </li></ul></ul><ul><ul><li>Sharks </li></ul></ul><ul><ul><li>Farmed salmon </li></ul></ul><ul><ul><li>Orange Roughy </li></ul></ul><ul><ul><li>Chilean seabass (toothfish) </li></ul></ul>http://www.montereybayaquarium.org/cr/cr_seafoodwatch/download.aspx
  44. 49. Points to know: <ul><li>What factors affect the type of ecosystem that will develop? </li></ul><ul><li>Know the characteristics of the major terrestrial biomes. </li></ul><ul><li>Aquatic biomes can be categorized by several axes: </li></ul><ul><ul><li>Marine, Freshwater, or Estuary </li></ul></ul><ul><ul><li>Benthic, Pelagic, Littoral </li></ul></ul><ul><li>What are some differences between lakes/ponds and rivers/streams? </li></ul><ul><li>Understand differences between primary and secondary succession. </li></ul>
  45. 50. Points to know 2 <ul><li>What is channelization? Why is it done and what problems can it cause? </li></ul><ul><li>What can be the problems with dams and flood control? How do they affect sediment & water flows, fish migration, and floodplains? </li></ul><ul><li>What is a wetland and how much has been lost in the U.S.? What ecosystem services do they provide? </li></ul><ul><li>Why is oceanic fishing important (2 reasons)? Name 3 reasons for overfishing. What does the bluefin tuna example tell us about the effects politics & conflict of interests on fishing policies? </li></ul><ul><li>What are the pros and cons of aquaculture? </li></ul><ul><li>Why should you care about the destruction of coral reefs? </li></ul>