Chapter 12 Sustaining Aquatic Biodiversity
Aquatic Biodiversity • What do we know? • Only have explored 5% of the oceans • Greatest marine biodiversity occurs in coral reefs, estuaries and deep ocean floor. • Biodiversity is higher by the coast then the open sea • Biodiversity is greater in the bottom region of the ocean then the surface region
Aquatic Biodiversity • Values of Aquatic Biodiversity • Provide us with an estimated $21 trillion a year • At least 3.5 billion people depend on the oceans for survival • Many marine organisms have chemicals used in medicines • Freshwater systems provide services worth $1.7 trillion.
Loss and degradation 90% of fish living in the oceans spawn in coral reefs, mangroves, coastal wetlands or rivers. 20% of coral reefs have been destroyed. Up to 58% could be lost by 2050. 15% of worlds seagrass beds have disappeared since 1995 Sea level is rising- over the past 100 years level has risen by 10-25 cm Mangroves and wetlands have been lost to development Trawlers are destroying bottom ecosystems Human Impacts on Aquatic Biodiversity
Human Impacts on Aquatic Biodiversity • Invasive Species • Blamed for about 2/3 of fish extinctions in the US between 1900 and 2000 and cost an average of $16 million per HOUR. • Most arrive in ballast water • Examples: • Asian swamp eel eats many types of fish. It can withstand cold weather, drought, fires and predators because it can burrow. It can also breath air.
Human Impacts on Aquatic Biodiversity • Population Growth and Pollution • 2006 45% of the worlds population lives on or near a coast. • Estimated that 80% of ocean pollution comes from land based activities • Amount of nitrate fertilizers has doubled since 1860. Excess nutrients can cause eutrophication which can lead to algae blooms and then fish die offs. • Toxic pollutants from industrial and urban areas • Plastic pollution kills 1 million seabirds and 100,000 sea turtles.
Human Impacts on Aquatic Biodiversity • Overfishing and Extinction • Modern industrialized fishing can deplete marine life very rapidly. Can cause 80% depletion of a target fish species in only 10-15 years. • Usually leads to commercial extinction. • In 1992 Canada’s cod fishery collapsed. Still has not recovered. • 90% of the large open ocean fish have disappeared since 1950 • Can cause bycatch – organisms caught unintentionally in nets.
Human Impacts on Aquatic Biodiversity • Why is it difficult to protect? • Human ecological footprint is expanding so rapidly that it is difficult to monitor the impacts. • Damage to oceans is not visible to humans • People view the sea as an inexhaustible resource that can absorb an infinite number of pollutants • Most oceans lie outside the legal jurisdiction of any country.
Protecting and Sustaining Marine Biodiversity • Legal and economic approaches • 1975 CITES • 1979 Global Treaty on Migratory Species • US Marine Mammal Protection Act of 1972 • US Endangered Species Act of 1973 • US Whale and Conservation and Protection Act of 1973 • 1995 International Convention on Biological Diversity
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
Case Study: 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
Protecting and Sustaining Marine Biodiversity • Marine sanctuaries • International law states that a country’s offshore fishing zone extends to 370km (200 miles) from its shores. • Exclusive economic zones: • High seas: • Marine protected areas (MPAs): • Marine reserves: • Works and works fast – fish populations double, fish size grows by a third, fish reproduction triples, species diversity increases by a fourth.
Protecting and Sustaining Marine Biodiversity • Less than 0.3% of the world’s ocean area consists of fully protected marine reserves. • Scientist call for 30% of the ocean to become protected marine reserves. • World’s largest marine reserve was created in 2006. • 360,000 sq km (140,000 sq miles) surrounding some Hawaiian island.
Protecting and Sustaining Marine Biodiversity • Integrated coastal management • Community based effort to develop and use coastal resources more sustainably. • Revamping US Ocean Policy • 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.
Managing and Sustaining Marine Fisheries • Make better estimates of fish populations. • Traditional approach is to use a maximum sustainable yield (MSY): • Hasn’t been very successful • Optimum sustainable yield (OSY): • Multispecies management:
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
PROTECTING, SUSTAINING, AND RESTORING WETLANDS • US has lost more then ½ of its wetlands since 1900 • Louisiana has 40% of US salt marshes. Much is lost due to sinking. Dams and levees block sediment from flowing down Mississippi River that would normally be deposited. Plus, sea level is rising due to climate change. • Federal permits are required now to fill or dredge a wetland. This has help cut he average annual wetland lost by 80% since 1969. • Mitigation banking:
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 12-8
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
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 • The project has been attempting to restore the Everglades and Florida water supplies. Figure 12-10
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 ($15 million/yr for chemical to kill young), zebra mussel ($140 million a year), quagga mussel, Asian carp.
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 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).
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