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Chapter 12

Chapter 12. 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. Figure 12-1. Core Case Study: A Biological Roller Coaster Ride in Lake Victoria.

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Chapter 12

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  1. Chapter 12 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. Figure 12-1

  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. AQUATIC BIODIVERSITY • Fairly little known about the biodiversity of the world’s marine and freshwater systems. • Little exploration • Greatest marine biodiversity occurs in coral reefs, estuaries and the deep ocean floor. • Biodiversity is higher near the coast and bottom because of habitat and food source variety.

  5. AQUATIC BIODIVERSITY • Marine and freshwater systems provide important ecological and economic services. • Ecological services ~ $21 trillion/year • >1/2 the world’s population dependent on seas for primary food source • Antibiotic/anticancer: algae, sea anemones, sponges, mollusks, and fish

  6. HUMAN IMPACTS ON AQUATIC BIODIVERSITY • Greatest threat to biodiversity of oceans = loss and degradation of habitats. • Approximately 20% of the world's coral reefs have been destroyed, 20% damaged • Sea levels risen 10-25 centimeters in past 100yrs • > ½ world’s mangroves have been removed. • > ½ world’s coastal wetlands have been removed • Dredging & trawling destroy benthos • Water held behind dams = 3-6x that in flowing rivers

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

  8. 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.

  9. HUMAN IMPACTS ON AQUATIC BIODIVERSITY • 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.

  10. Population Growth and Pollution • Each year plastic items dumped from ships and left as litter on beaches threaten marine life. Figure 12-3

  11. Population Growth and Pollution

  12. 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. • Modern industrial fishing can deplete 80% of target species within 10-15 yrs • Leads to commercial extinction • 90% of large open-ocean fish gone since 1950 • Tuna, swordfish, marlin • > ¼ of annual fish catch = bycatch (thrown back) • Includes birds, turtles & mammals

  13. 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. 12-A, p. 255

  14. Why is it Difficult to Protect Aquatic Biodiversity? • Rapidly increasing human impacts • Human ecological footprint is expanding. • Many people incorrectly view the oceans as an inexhaustible resource. • Invisibility of problems • Citizen unawareness • Lack of legal jurisdiction

  15. PROTECTING AND SUSTAINING MARINE BIODIVERSITY • Ways to reduce premature extinction of marine species: • Laws & International treaties • 1975 Convention on International Trade in Endangered Species (CITES) • 1979 Global Treaty on Migratory Species • U.S. Endangered Species Act of 1973 • U.S. Whale Conservation and Protection Act of 1976 • 1995 International Convention on Biological Diversity • Education

  16. PROTECTING AND SUSTAINING MARINE BIODIVERSITY • All seven major turtle species are threatened or endangered because of human activities. • Coastal development • Pollution • Plastics • Direct harvest • Invasives • Vessel strikes • Since 1989 the U.S. government has required offshore shrimp trawlers to use turtle exclusion devices (TEDs) • Sea turtle tourism brings in 3x as much money as the sale of turtle products (meat, leather, eggs).

  17. PROTECTING AND SUSTAINING MARINE BIODIVERSITY • Reconciliation ecology: • Involves restaurants or other commercial establishments, working with conservation programs to both protect species and provide tourist revenue.

  18. Case Study: The Florida Manatee and Water Hyacinths • Manatee can eat unwanted Water Hyacinths. • Endangered due to: • Habitat loss. • Entanglement from fishing lines and nets. • Hit by speed boats. • Stress from cold. • Low reproductive rate Figure 12-B

  19. Case Study: Commercial Whaling • After many of the world’s whale species were overharvested, the IWC banned commercial whaling in 1986, but the ban may be overturned. Figure 12-6

  20. Case Study: Commercial Whaling • Cetaceans = marine mammals • Toothed & Baleen • Easy targets: • Large & surface for air • 8 of 11 major species commercially extinct, blue whale – biologic extinction • IWC: est. 1946, set quotas • Based on inadequate data • No power of enforcement • US banned whaling and whale products in 1970 Figure 12-5

  21. Case Study: Commercial Whaling • Despite ban, Japan, Norway, and Iceland kill about 1,300 whales of certain species for scientific purposes. • Meat is still sold commercially. • These countries work to overthrow ban • Scientists think recovery estimates are too high. • Especially blue whale • Only 10,00 remaining • Slow maturation – 25yrs • 1 calf every 2-5 years Figure 12-5

  22. How Would You Vote? • Should carefully controlled commercial whaling be resumed for species with populations of 1 million or more? • No. The hunting of whales is no longer necessary and simply encourages disrespect for these intelligent giants. • Yes. Some whale species have recovered and products from them are valuable resources for humans.

  23. PROTECTING AND SUSTAINING MARINE BIODIVERSITY • Nations have sovereignty over waters and seabed up to 12 miles offshore. • Exclusive Economic Zone (EEZ) = 200 miles from shore; not regulated to sustain fish harvest, rather, they have been overfished.

  24. PROTECTING AND SUSTAINING MARINE BIODIVERSITY • Nations have established marine sanctuaries, but many are only partially protected. • The World Conservation Union helped establish a global system of marine protected areas (MPAs). • 1,300 MPAs/200 in U.S.; most allow ecologically harmful activities like trawling , dredging, and resource extraction.

  25. 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. • Using solutions that preserve biodiversity & meet economic needs • US has 90 counties working on this, only 20 implemented

  26. PROTECTING AND SUSTAINING MARINE BIODIVERSITY • In 2006, U.S. president George W. Bush created the world’s largest protect marine area—140,00 square miles (360,000 square kilometers)—the Northwest Hawaiian Marine National Monument.

  27. 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.

  28. MANAGING AND SUSTAINING MARINE FISHERIES • Coastal & open-water fish species are overfished • Many ways to manage marine fisheries more sustainably and protect marine biodiversity. • Project fish populations: maximum sustainable yield: however pop/growth data is unreliable, interspecific effects unmeasured, quotas difficult to enforce The maximum sustainable yield can be calculated as rN where r is the rate of natural increase and N is the average number of animals in the population during the year

  29. MANAGING AND SUSTAINING MARINE FISHERIES OTHER APPROACHES • Optimum sustainable yield: • Allows room for error & interspecific interactions • Multi-species management: • Considers competition & predator-prey interactions

  30. MANAGING AND SUSTAINING MARINE FISHERIES • Some fishing communities regulate fish harvests on their own and others work with the government to regulate them. • Modern fisheries have weakened the ability of many coastal communities to regulate their own fisheries. • LARGE industrial boats/fleets have decreased local fisheries

  31. MANAGING AND SUSTAINING MARINE FISHERIES • Many communities are CO-managed: • Government sets and allocates quotas • Government limits seasons and gear • Communities allocate Individual Transfer Quotas (ITQs): can be bought, sold, leased • Hasn’t lessened by-catch/but privately owned now • Public still responsible for enforcement costs (could make quota owners pay instead) • Small scale squeezed out • Poaching may increase (record keeping/observers) • Quotas too high (limit to 10-50% below MSY)

  32. Solutions Managing Fisheries Fishery Regulations Set catch limits well below the maximum sustainable yield Improve monitoring and enforcement of regulations Bycatch Use wide-meshed nets to allow escape of smaller fish Use net escape devices for sea birds and sea turtles Ban throwing edible and marketable fish back into the sea Economic Approaches Sharply reduce or eliminate fishing subsidies Charge fees for harvesting fish and shellfish from publicly owned offshore waters Certify sustainable fisheries Aquaculture Restrict coastal locations for fish farms Control pollution more strictly Depend more on herbivorous fish species Protected Areas Establish no-fishing areas Establish more marine protected areas Rely more on integrated coastal management Nonnative Invasions Kill organisms in ship ballast water Filter organisms from ship ballast water Dump ballast water far at sea and replace with deep-sea water Consumer Information Label sustainably harvested fish Publicize overfished and threatened species Fig. 12-7, p. 261

  33. PROTECTING, SUSTAINING, AND RESTORING WETLANDS • Coastal and inland wetlands: • Reservoirs of aquatic biodiversity

  34. PROTECTING, SUSTAINING, AND RESTORING WETLANDS • 50% of US wetlands filled/destroyed; climate change will destroy more (rising sea levels) • Requiring government permits for filling or destroying U.S. wetlands has slowed their loss, but attempts to weaken this protection continue. • US ‘zero-net-loss’ goal (mitigation banking) Figure 12-8

  35. Solutions Protecting Wetlands Legally protect existing wetlands Steer development away from existing wetlands Use mitigation banking only as a last resort Require creation and evaluation of a new wetland before destroying an existing wetland Restore degraded wetlands Try to prevent and control invasions by nonnative species Fig. 12-9, p. 264

  36. Case Study: Restoring the Florida Everglades • The world’s largest ecological restoration project: • 50% everglades gone, dried out, subject to invasives

  37. Case Study: Restoring the Florida Everglades • 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: threatens reefs, hinders diving, fishing, and tourism

  38. Restoring the Florida Everglades • The project has been attempting to restore the Everglades and Florida water supplies. • Restore river flow • Remove canals/levees • Buy farmland & create artificial wetlands • Create reservoirs for drinking water • Recapture 80% of water and return it to Everglades Figure 12-10

  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.

  41. How Would You Vote? Should federal efforts to rebuild wild salmon populations in the Columbia River Basin be abandoned? • No. Restoring salmon populations is critical for the environmental health of the river and surrounding forests. • Yes. The restoration program would create unnecessary and severe economic hardships for local residents.

  42. PROTECTING, SUSTAINING, AND RESTORING LAKES AND RIVERS • We can help sustain freshwater fisheries by building and protecting populations of desirable species, preventing over-fishing, and decreasing populations of less desirable species. • A federal law helps protect a tiny fraction of U.S. wild and scenic rivers from dams and other forms of development. • National Wild and Scenic Rivers Act (1968) – protects rivers and segments with outstanding scenic, recreational, geological, wildlife and historical or cultural values

  43. PROTECTING, SUSTAINING, AND RESTORING LAKES AND RIVERS • THREE-TIERED CLASSIFICATION SCHEME: • WILD RIVERS: relatively inaccessible, not permitted to be widened, straightened, dredged, filled or dammed • SCENIC RIVERS: free from dams, mostly undeveloped, great scenic value, somewhat accessible • RECREATIONAL RIVERS: readily accessible, some dams or development • Only 0.2% of 3.5 million miles of river protected; 17% dammed • Research, protection, restoration and integrated management needed

  44. Natural Capital Ecological Services of Rivers • Deliver nutrients to sea to help sustain coastal fisheries • Deposit silt that maintains deltas • Purify water • Renew and renourish wetlands • Provide habitats for wildlife Fig. 12-11, p. 267

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