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Sustaining Aquatic Biodiversity Chapter 12 By the Numbers About 50% of the human population depends on the seas for primary source of food. About 90% of fish spawn in the world’s coral reefs, mangrove swamps, coastal wetlands or rivers Coral reefs have the greatest biodiversity About 1% of Earth’s surface is made of freshwater systems. Major Causes of Species Loss in Marine Ecosystems (HIPPCO) Habitat destruction Pollution Erosion Climate change Invasive species – caused over ½ of fish extinctions of last centuary in the US Overfishing – lower size of fish populations; decreases marine keystone species All are made worse by the growth of the human population A Biological Roller Coaster Ride in Lake Victoria Loss of biodiversity and cichlids Nile perch: deliberately introduced Frequent algal blooms Nutrient runoff Spills of untreated sewage Less algae-eating cichlids Reasons Why Protecting Aquatic Biodiversity is Difficult 1. Expanding human ecological footprint 2. Most of the ocean area lies outside political jurisdiction of any one country 3. Damage to oceans is not visible to most people 4. Many view the ocean as an inexhaustible resource Human Activities Are Destroying Habitats Habitat loss and degradation Marine – only 4% of the world’s oceans are not affected by pollution Coastal Ocean floor: fishing methods Freshwater Dams Excessive water withdrawal Invasive species Invasive Species Are Degrading Biodiversity Threaten native species Disrupt and degrade whole ecosystems 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— Invasive water hyacinth Repeated Invasions by Alien Species in the Great Lakes Collectively, world’s largest body of freshwater Invaded by at least 162 nonnative species Sea lamprey Zebra mussel Good and bad Quagga mussel Asian carp Zebra Mussels Attached to a Water Current Meter in Lake Michigan, U.S. How Carp Have Muddied Some Waters Lake Wingra, Wisconsin (U.S.): eutrophic, excessive nutrient inputs from run off with fertilizers from farms/lawns Contains invasive species Purple loosestrife and the common carp, which devour the algae Removed carp from an area of the lake This area appeared to recover Population Growth and Pollution Can Reduce Aquatic Biodiversity Nitrates and phosphates mainly from fertilizers enter water Leads to algal bloom and eventual eutrophication, fish die offs Toxic pollutants from industrial and urban areas, plastic items Hawaiian Monk Seal Climate Change Is a Growing Threat Global warming: sea levels will rise and aquatic biodiversity is threatened ◦ Coral reefs ◦ Swamp some low-lying islands ◦ Drown many highly productive coastal wetlands New Orleans, Louisiana, and New York City Overfishing and Extinction Marine and freshwater fish Threatened with extinction by human activities more than any other group of species Commercial extinction – industrialized fishing fleets can deplete marine life at a much faster rate. Can cause 80% in 10-15 years Collapse of the cod fishery of the coast of Newfoundland and its domino effect leading to collapse of other species By-catch – non-target species that are caught and killed duringy commercial fishing practices (seals, dolphins). 34% of marine, 71% of fresh water species face extinction within your life time. 900,000 800,000 700,000 Fish landings (tons) 600,000 500,000 400,000 1992 300,000 200,000 100,000 0 1900 1920 1940 1960 Year 1980 2000 Fig. 11-6, p. 254 Major Commercial Fishing Practices • Trawl fishing – involves dragging a weighted, funnel-shaped net along ocean floor in order to catch shellfish, flounder; most destructive of fishing practices. • Purse seine – practice used to capture schooling fish (tuna); surrounds and encloses with a net. • Drift net – uses hanging vertical nets in the water column with buoys to catch fish by gills. • Longline fishing – involves putting out lines hung with thousands of baited hooks. Industrial Fish Harvesting Methods are Vacuuming the Seas • Trawl fishing – shrimp & scallops • Purse seine – tuna & mackarel • Longline fishing – tuna, swordfish & sharks • Drift net – 1992 ban on using nets longer than 2.5 km Aquaculture • Deep sea aquaculture cage – Form of “fish farming” – These strains of fish are usually weaker than the “wild” form of the species. If weaker strains escape into the wild, could weaken wild population. Protect and Sustain Marine Biodiversity • We can help to sustain marine biodiversity by – Using laws and incentives to protect species – Setting aside marine reserves to protect ecosystems – Using community-based coastal management – Page 261 Legislation 1. Convention on International Trade in Endangered Species (CITES) 1973 2. Global Treaty on Migratory Species 1979 3. US Marine Mammal Protection Act 1972 4. US Endangered Species Act 1973 5. US Whale Conservation & Protection Act 1976 6. International Convention on Biological Diversity 1995 International Whaling Commission • Established by the International Convention for the Regulation of Whaling in 1946 • Allows Eskimos to continue hunting whales (cultural reasons) • Japan, Norway and Iceland kill about 1300 whales per year for “scientific purposes” – Japan more than doubled whaling catch in 2005 Protecting Whales: Success Story… So Far Cetaceans: Toothed whales and baleen whales 1946: International Whaling Commission (IWC) – set annual quotas 1970: U.S. Stopped all commercial whaling Banned all imports of whale products 1986: moratorium on commercial whaling Japan ,Norway, Iceland, Russia do not support the IWC ban Economic Incentives Can Be Used to Sustain Aquatic Biodiversity Tourism – example : sea turtles, worth more to local communities alive than dead (WWF) Economic rewards Marine Sanctuaries Protect Ecosystems and Species Offshore fishing extends to 370 kilometers Exclusive economic zones-can take certain quotas of fish High seas-beyond legal jurisdiction of any country Law of the Sea Treaty – world’s coastal nations have jurisdiction over 36% of the ocean surface and 90% of the world’s fish stocks Marine Protected Areas (MPAs) – 4000 world wide, 200 in US waters In 2006, President George W. Bush created the world’s largest marine reserve in Hawaii. Ecosystem approach to sustainability Core zone No human activity allowed Less harmful activities allowed E.g., recreational boating and shipping Fully protected marine reserves work fast Fish populations double Fish size grows Reproduction triples Species diversity increase by almost one-fourth Protecting Marine Biodiversity: Individuals and Communities Together Integrated Coastal Management Community-based group to prevent further degradation of the ocean More that 100 such groups seek reasonable short term trade offs that can lead to long term ecological and economic benefits How Should We Manage and Sustain Marine Fisheries? Sustaining marine fisheries will require improved monitoring of fish populations, cooperative fisheries management among communities and nations, reduction of fishing subsidies, careful consumer choices in seafood markets. Estimating and Monitoring Fishery Populations is the First Step Maximum Sustained Yield (MSY) – model to project the maximum number of fish that can be harvested from a fish stock without causing a population drop. Optimum Sustained Yield (OSY) – takes into account interactions with other species and provides more room for error. Tragedy in the commons activity Some Communities Cooperate to Regulate Fish Harvests Community management of the fisheries – allotment and enforcement systems. Norway’s Lofoten fishery (cod) Co-management of the fisheries with the government – sets quotas for various species and divide the quotas among communities. Government Subsidies Can Encourage Overfishing-$30-34 billion around the world 2007: World Trade Organization, U.S. Proposed a ban on fishing subsidies Reduce illegal fishing on the high seas and in coastal waters Close ports and markets to such fishers Check authenticity of ship flags Prosecution of offenders Some Countries Use the Marketplace to Control Overfishing Individual transfer rights (ITRs) Control access to fisheries New Zealand and Iceland Difficult to enforce US 1995 to protect the halibut fishery Problems with the ITR approach transfer ownership of fisheries in publically owned waters to private owners squeeze out small fishing companies Consumer Choices Can Help to Sustain Fisheries and Aquatic Biodiversity 1997: Marine Stewardship Council (MSC), London – 20 nations Certifies that fish caught using sustainable practices Manage global fisheries more sustainably Individuals Organizations Governments How Should We Protect and Sustain Wetlands and Beach Areas? To maintain the ecological and economic services of wetlands, we must maximize preservation of remaining wetlands and restoration of degraded and destroyed wetlands. Best long-range strategy to reduce beach erosion: Prevent development on beach areas or allow development only behind protective dunes Coastal Wetlands 1. Serve as buffers against storms 2. Trap sediments and filter water 3. Act as nurseries for fish, shellfish and birds 4. More than half of the coastal wetlands have disappeared Florida Everglades – Largest Ever Wetlands Restoration Project “River of Grass”: south Florida, U.S. Since 1948: damaged Drained Diverted Paved over Nutrient pollution from agriculture Invasive plant species 1947: Everglades National Park unsuccessful protection project Can We Restore the Florida Everglades? 1970s: political haggling 1990: Comprehensive Everglades Restoration Plan (CERP) Restore the curving flow of most of the Kissimmee River Remove canals and levees in strategic locations Flood 240 sq. km farmland to create artificial marshes Can We Restore the Florida Everglades? Comprehensive Everglades Restoration Plan (CERP) cont… Create reservoirs and underground water storage areas Build new canals, reservoirs and efficient pumping systems US Army Corps of Engineers – federal agency responsible for undoing development (dredging canals, levees)in Everglades. Ironically, this same agency oversaw the development of the Everglades since the 1940s. Plan isn’t working……not sure why. The World’s Largest Restoration Project Managing River Basins Is Complex and Controversial 40% of the world’s rivers have been dammed or otherwise engineered Columbia River: U.S. and Canada Dam system 119 dams , 19 of which are hydroelectric power plants Pros –electricity ; con –salmon affected Snake River: Washington state, U.S. Hydroelectric dams removed Pro – salmon saved ; con – economy affected Dams and Reservoirs 1. May kill young salmon as they pass through turbines 2. Slow downstream migration, exposing juvenile salmon to more predation 3. May prevent upstream migration of mature salmon Columbia River Rehabilitation and Restoration Ecosystem rehabilitation and salmon restoration on the Columbia River includes 1. Building new hatcheries upstream of the dams 2. Putting 40,000 miles of stream off limits to hydropower development 3. Reducing runoff of silt from logging roads. Natural Capital: Ecological Services of Rivers Protect Freshwater Ecosystems by Protecting Watersheds Freshwater ecosystems protected through Laws Economic incentives Restoration efforts National Wild and Scenic Rivers Act-reestablish protection of rivers Sustainable management of freshwater fishes Priorities for Protecting Biodiversity, Ecosystem Services 2002: Edward O. Wilson Complete the mapping of the world’s terrestrial and aquatic biodiversity Keep old-growth forests intact; cease their logging Identify and preserve hotspots and deteriorating ecosystem services that threaten life Ecological restoration projects Make conservation financially rewarding
