Presentation on theme: "Chapter 12 Sustaining Aquatic Biodiversity. Lake Victoria Lake Victoria has lost their endemic fish species- the cichlid- to large introduced predatory."— Presentation transcript:
Lake Victoria Lake Victoria has lost their endemic fish species- the cichlid- to large introduced predatory fish. Figure 12-1
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.
AQUATIC BIODIVERSITY Little is known about the biodiversity of the world’s marine and freshwater systems. ◦ The greatest marine biodiversity occurs in coral reefs, estuaries and the deep ocean floor. ◦ Biodiversity is higher near the coast and surface because of habitat and food source variety.
HUMAN IMPACTS ON AQUATIC BIODIVERSITY 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.
HUMAN IMPACTS ON AQUATIC BIODIVERSITY Area of ocean before and after a trawler net, acting like a giant plow, scraped it. Importance of zooxanthallaezooxanthallae Figure 12-2
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.
Population Growth and Pollution Each year plastic items dumped from ships and left as litter on beaches threaten marine life. Figure 12-3
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.
Fig. 12-A, p. 255 Fish farming in cage Trawler fishing Spotter airplane Sonar Trawl flap Trawl lines Purse-seine fishing Trawl bag Fish school Drift-net fishing Long line fishing Lines with hooks Fish caught by gills Deep sea aquaculture cage Float Buoy
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.
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. ◦ Sea turtle tourism brings in almost three times as much money as the sale of turtle products.
PROTECTING AND SUSTAINING MARINE BIODIVERSITY Six of the world’s seven major turtle species are threatened or endangered because o human activities. Figure 12-4
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
Commercial Whaling Commercial Whaling After many of the world’s whale species were overharvested, commercial whaling was banned in 1960, but the ban may be overturned. Figure 12-6
Case Study: Commercial Whaling Despite ban, Japan, Norway, and Iceland kill about 1,300 whales of certain species for scientific purposes. ◦ Although meat is still sold commercially. Figure 12-5
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.
Fig. 12-7, p. 261 Solutions Managing Fisheries Fishery Regulations Set catch limits well below the maximum sustainable yield Improve monitoring and enforcement of regulations Economic Approaches Sharply reduce or eliminate fishing subsidies Charge fees for harvesting fish and shellfish from publicly owned offshore waters Certify sustainable fisheries Protected Areas Establish no-fishing areas Establish more marine protected areas Rely more on integrated coastal management Consumer Information Label sustainably harvested fish Publicize overfished and threatened species 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 Aquaculture Restrict coastal locations for fish farms Control pollution more strictly Depend more on herbivorous fish species 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
PROTECTING, SUSTAINING, AND RESTORING WETLANDS Requiring government permits for filling or destroying U.S. wetlands has slowed their loss. Why are wetlands so important? Figure 12-8
Fig. 12-9, p. 264 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
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.
Restoring the Florida Everglades video Figure 12-10
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.
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 protecting rivers from development or dams. ◦ National Wild and Scenic Rivers Act (1968).
Fig. 12-11, p. 267 Deliver nutrients to sea to help sustain coastal fisheries Deposit silt that maintains deltas Purify water Renew and renourish wetlands Provide habitats for wildlife Natural Capital Ecological Services of Rivers