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Sustaining Aquatic Biodiversity

Sustaining Aquatic Biodiversity. Core Case Study: A Biological Roller Coaster Ride in Lake Victoria. Lake Victoria has lost their endemic fish species to large introduced predatory fish. Core Case Study: A Biological Roller Coaster Ride in Lake Victoria.

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Sustaining Aquatic Biodiversity

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  1. Sustaining Aquatic Biodiversity

  2. Core Case Study: A Biological Roller Coaster Ride in Lake Victoria Lake Victoria has lost their endemic fish species to large introduced predatory fish.

  3. Core Case Study: A Biological Roller Coaster Ride in Lake Victoria Reasons for Lake Victoria’s loss of biodiversity: Introduction of Nile perch. Lake experienced algal blooms from nutrient runoff. Invasion of water hyacinth has blocked sunlight and deprived oxygen. Nile perch is in decline because it has eaten its own food supply.

  4. 11-1 What Are the Major Threats to Aquatic Biodiversity? • Concept 11-1 Aquatic species are threatened by habitat loss, invasive species, pollution, climate change, and overexploitation, all made worse by the growth of the human population.

  5. Three General Patterns of Marine Biodiversity The greatest marine biodiversity occurs in coral reefs, estuaries, and the deep-ocean floor Biodiversity is higher near coasts than in the open sea because of the greater variety of producers and habitats in coastal areas Biodiversity is higher in the bottom region of the ocean than in the surface region because of the greater variety of habitats and food sources on the ocean bottom

  6. Human Activities Are Destroying and Degrading Aquatic Habitats Human activities have destroyed, disrupted or degraded a large proportion of the world’s coastal, marine and freshwater ecosystems. Approximately 20% of the world's coral reefs have been destroyed. During the past 100 years, sea levels have risen 10-25 centimeters. We have destroyed more than 1/3 of the world’s mangrove forests for shipping lanes.

  7. Shrimp farms in areas that were once mangrove forests

  8. Additional ways humans degrade our ocean environment

  9. HUMAN IMPACTS ON AQUATIC BIODIVERSITY Area of ocean before and after a trawler net, acting like a giant plow, scraped it. Figure 12-2

  10. HUMAN IMPACTS ON AQUATIC BIODIVERSITY Harmful invasive species are an increasing threat to marine and freshwater biodiversity. Bioinvaders are blamed for about 2/3 of fish extinctions in the U.S. between 1900-2000. Almost half of the world’s people live on or near a coastal zone and 80% of ocean water pollution comes from land-based human activities.

  11. Invasive Species Are Degrading Aquatic Biodiversity • Invasive species • Threaten native species • Disrupt and degrade whole ecosystems • Three examples • Water hyacinth: Lake Victoria (East Africa) • Asian swamp eel: waterways of south Florida • Purple loosestrife: indigenous to Europe • Treating with natural predators—a weevil species and a leaf-eating beetle—Will it work?

  12. Asian Rice Eel

  13. Population Growth and Pollution Each year plastic items dumped from ships and left as litter on beaches threaten marine life.

  14. It’s just a plastic bag! It can’t hurt anyone. Sea turtle off the coast of Florida

  15. What can you do to make sure this does not continue?

  16. Overfishing and Extinction: Gone Fishing, Fish Gone About 75% of the world’s commercially valuable marine fish species are over fished or fished near their sustainable limits. Big fish are becoming scarce. Smaller fish are next. We throw away 30% of the fish we catch. We needlessly kill sea mammals and birds.

  17. Human impacts on marine biodiversity Coral reef destruction Sea level rising Destruction of mangrove forests Trawler nets destroying ocean floor Invasive species Coastal development Trash Overfishing

  18. Industrial fish harvesting methods Trawler fishing: dragging net along ocean floor Purse-seine fishing: surround fish with net Long-line fishing: 80 miles of fishing line with thousands of baited hooks Drift-net fishing: 80 miles of drifting nets below the surface

  19. Problems with industrial fish harvesting methods Trawler fishing: like clear-cutting forest; destroys ocean floor; captures endangered seals and turtles Purse-seine fishing: kills hundreds of dolphins Long-line fishing: hooks endangered sea turtles, albatross, pilot whales, sharks, dolphins Drift-net fishing: kills non-target fish species and marine mammals

  20. Trawler fishing Fish farming in cage Spotter airplane Sonar Purse-seine fishing Trawl flap Trawl lines Fish school Trawl bag Drift-net fishing Long line fishing Buoy Float Lines with hooks Deep sea aquaculture cage Fish caught by gills Fig. 11-7, p. 256

  21. Trawler fishing By-catch

  22. Purse-seine fishing

  23. Long-line fishing

  24. Several countries have banned the use of drift nets or they are carefully monitoring the use of drift nets

  25. Drift-nets catch and kill anything caught in the net

  26. Why is it Difficult to Protect Aquatic Biodiversity? Rapid increasing human impacts, the invisibility of problems, citizen unawareness, and lack of legal jurisdiction hinder protection of aquatic biodiversity. Human ecological footprint is expanding. Much of the damage to oceans is not visible to most people. Many people incorrectly view the oceans as an inexhaustible resource.

  27. Case Study: Protecting Whales: A Success Story… So Far • Cetaceans: Toothed whales and baleen whales • 1946: International Whaling Commission (IWC) • 1970: U.S. • Stopped all commercial whaling • Banned all imports of whale products • 1986: moratorium on commercial whaling • Pros • Cons

  28. Case Study: Holding Out Hope for Marine Turtles • Carl Safina, Voyage of the Turtle • Studies of the leatherback turtle • Threats to the leatherbacks • Trawlers • Pollution • Climate change • Communities protecting the turtles

  29. PROTECTING AND SUSTAINING MARINE BIODIVERSITY Laws, international treaties, and education can help reduce the premature extinction of marine species. Since 1989 the U.S. government has required offshore shrimp trawlers to use turtle exclusion devices (TEDs). Sea turtle tourism brings in almost three times as much money as the sale of turtle products.

  30. PROTECTING AND SUSTAINING MARINE BIODIVERSITY Six of the world’s seven major turtle species are threatened or endangered because of human activities. Figure 12-4

  31. Laws and international treaties protecting marine biodiversity CITES (Convention on International Trade in Endangered Species ) Global Treaty on Migratory Species Marine Mammal Protection Act ESA (Endangered Species Act of 1973 ) Whale Conservation and Protection Act International Convention on Biological Diversity Offshore fishing Exclusive economic zones High seas Law of the Sea Treaty Marine Protected Areas (MPAs)

  32. Exclusive Economic Zone

  33. PROTECTING AND SUSTAINING MARINE BIODIVERSITY Fully protected marine reserves make up less than 0.3% of the world’s ocean area. Studies show that fish populations double, size grows by almost a third, reproduction triples and species diversity increases by almost one fourth. Some communities work together to develop integrated plans for managing their coastal areas.

  34. Integrated Coastal Management • Fisheries scientists • Conservationists • Citizens • Business interests • Developers • Politicians Competing for the same resource – identify shared problems and goals and attempt to develop workable, cost-effective, and adaptable solutions that preserve biodiversity and environmental quality while meeting economic and social needs.

  35. Revamping Ocean Policy Two recent studies called for an overhaul of U.S. ocean policy and management. Develop unified national policy. Double federal budget for ocean research. Centralize the National Oceans Agency. Set up network of marine reserves. Reorient fisheries management towards ecosystem function. Increase public awareness.

  36. PROTECTING, SUSTAINING, AND RESTORING WETLANDS Requiring government permits for filling or destroying U.S. wetlands has slowed their loss, but attempts to weaken this protection continue. Figure 11.13 Natural capital restoration: wetland restoration at Fort Erie, Ontario, Canada before (right) and after (left).

  37. Case Study: Restoring the Florida Everglades The world’s largest ecological restoration project involves trying to undo some of the damage inflicted on the Everglades by human activities. 90% of park’s wading birds have vanished. Other vertebrate populations down 75-95%. Large volumes of water that once flowed through the park have been diverted for crops and cities. Runoff has caused noxious algal blooms.

  38. Restoring the Florida Everglades The project has been attempting to restore the Everglades and Florida water supplies. Figure similar to 11-14

  39. PROTECTING, SUSTAINING, AND RESTORING LAKES AND RIVERS Lakes are difficult to manage and are vulnerable to planned or unplanned introductions of nonnative species. For decades, invasions by nonnative species have caused major ecological and economic damage to North America’s Great lakes. • Sea lamprey, zebra mussel, quagga mussel, Asian carp.

  40. PROTECTING, SUSTAINING, AND RESTORING LAKES AND RIVERS Dams can provide many human benefits but can also disrupt some of the ecological services that rivers provide. 119 dams on Columbia River have sharply reduced (94% drop) populations of wild salmon. U.S. government has spent $3 billion in unsuccessful efforts to save the salmon. Removing hydroelectric dams will restore native spawning grounds.

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