Sustaining aquatic biodiversity
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Sustaining Aquatic Biodiversity. Chapter 11. 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.

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A biological roller coaster ride in lake victoria l.jpg
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

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What Are the Major Threats to Aquatic Biodiversity?

  • Aquatic species are threatened by habitat loss, invasive species, pollution, climate change, and overexploitation, all made worse by the growth of the human population.

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We Have Much to Learn about Aquatic Biodiversity

  • Greatest marine biodiversity

    • Coral reefs

    • Estuaries

    • Deep-ocean floor

  • Biodiversity is higher

    • Near the coast than in the open sea

    • In the bottom region of the ocean than the surface region, greater variety of habitats

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Human Activities Are Destroying Habitats

  • Habitat loss and degradation - HIPPCO

    • Marine – only 4% of the world’s oceans are not affected by pollution

      • Coastal

      • Ocean floor: effect of trawlers, which drag huge nets weighted with heavy chains and steel plates, reduce coral reefs to rubble

    • Freshwater

      • Dams

      • Excessive water withdrawal

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Invasive Species Are Degrading Biodiversity

  • Invasive species

    • 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

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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

  • Dr. Richard Lathrop

    • Removed carp from an area of the lake

      • This area appeared to recover

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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

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Climate Change Is a Growing Threat Biodiversity

  • Global warming: sea levels will rise and aquatic biodiversity is threatened – in the past 100 years , average 10-20 cm and scientists estimate another 18-59 cm, perhaps as high as 1-1.6 m

    • Coral reefs

    • Swamp some low-lying islands

    • Drown many highly productive coastal wetlands

      • New Orleans, Louisiana, and New York City

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Overfishing and Extinction Biodiversity

  • 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

  • Bycatch – seals, dolphins. 34% of marine, 71% of fresh water species face extinction within your life time.

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900,000 Biodiversity





Fish landings (tons)














Fig. 11-6, p. 254

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Protecting and Restoring Mangroves Biodiversity

  • Protect and restore mangroves

    • Reduce the impact of rising sea levels

    • Protect against tropical storms and tsunamis

    • Cheaper than building concrete sea walls

    • Mangrove forests in Indonesia

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Industrial Fish Harvesting Methods are vacuuming the seas Biodiversity

  • Trawler fishing- shrimp, scallops

  • Purse-seine fishing

    tuna, mackarel

  • Longlining – tuna, swordfish, sharks

  • Drift-net fishing – 1992 ban on the use of drift nets longer than 2.5 km

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Protect and Sustain Marine Biodiversity.. Biodiversity

  • We can help to sustain marine biodiversity by using laws and economic incentives to protect species, setting aside marine reserves to protect ecosystems, and using community-based integrated coastal management.

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Legal Protection of Some Endangered and Threatened Marine Species

  • Why is it hard to protect marine biodiversity?

    • Human ecological footprint and fish print are expanding

    • Much of the damage in the ocean is not visible

    • The oceans are incorrectly viewed as an inexhaustible resource that can absorb an almost infinite amount of waste

    • Most of the ocean lies outside the legal jurisdiction of any country

    • Treaties - CITES, Marine Mammal Protection Act, Endangered Species Act, Whale Conservation and Protection Act, International Convention on Biological Diversity

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Protecting Whales: Success Story… So Far Species

  • 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

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Economic Incentives Can Be Used to Sustain Aquatic Biodiversity

  • Tourism – example : sea turtles, worth more to local communities alive than dead (WWF)

  • Economic rewards

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Holding Out Hope for BiodiversityMarine Turtles(6 out of 7 endangered)

  • Carl Safina, Voyage of the Turtle

    • Studies of the leatherback turtle

  • Threats to the leatherbacks

    • Trawlers destroy coral reefs which is their feeding grounds

    • Entangled in fishing nets and lines

    • Pollution –discarded plastic bags

    • Climate change- rising sea levels will flood nesting and feeding areas

  • Communities protecting the turtles

  • Turtle Excluder Devices on shrimp boats

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Marine Sanctuaries Protect Ecosystems and Species Net

  • 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

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Ecosystem approach to sustainability Net

  • Marine

    • Commercial fishing

    • Dredging reserves

    • Mining and waste disposal

  • 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

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    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

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    How Should We Manage and Sustain Marine Fisheries? Together

    • Sustaining marine fisheries will require improved monitoring of fish populations, cooperative fisheries management among communities and nations, reduction of fishing subsidies, and careful consumer choices in seafood markets.

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    Estimating and Monitoring Fishery Populations Is the First Step

    • Maximum sustained yield (MSY): maximum number of fish that can be harvested annually without causing a population drop

    • Optimum sustained yield (OSY)-interactions among species

    • Multispecies management – of a number of interacting species

    • Large marine systems:using large complex computer models

    • Precautionary principle because of the uncertainty of all the above methods

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    Some Communities Cooperate to Regulate Fish Harvests Step

    • 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.

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    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

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    Some Countries Use the Marketplace to Control Overfishing billion around the world

    • 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

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    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

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    SOLUTIONS Biodiversity

    Managing Fisheries

    Fishery Regulations


    Set catch limits well below the maximum sustainable yield

    Use wide-meshed nets to allow escape of smaller fish

    Use net escape devices for seabirds and sea turtles

    Improve monitoring and enforcement of regulations

    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

    Restrict coastal locations for fish farms

    Control pollution more strictly

    Protect Areas

    Depend more on herbivorous fish species

    Certify sustainable fisheries

    Establish no-fishing areas

    Nonnative Invasions

    Establish more marine protected areas

    Kill organisms in ship ballast water

    Rely more on integrated coastal management

    Filter organisms from ship ballast water

    Consumer Information

    Label sustainably harvested fish

    Dump ballast water far at sea and replace with deep- sea water

    Publicize overfished and threatened species

    Fig. 11-12, p. 265

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    How Should We Protect and BiodiversitySustain Wetlands?

    • To maintain the ecological and economic services of wetlands, we must maximize preservation of remaining wetlands and restoration of degraded and destroyed wetlands.

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    Coastal and Inland Wetlands Are Disappearing around the World

    • Highly productive wetlands

    • Provide natural flood and erosion control

    • Maintain high water quality; natural filters

    • Effect of rising sea levels

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    Can We Restore the Florida Everglades? World

    • “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

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    Can We Restore the Florida Everglades? World

    • 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

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    Can We Restore the Florida Everglades? World

    • Comprehensive Everglades Restoration Plan (CERP) cont…

      • Create reservoirs and underground water storage areas

      • Build new canals, reservoirs and efficient pumping systems

    • Why isn’t this plan working?

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    Protect and Sustain Freshwater Lakes, Rivers, and Fisheries World

    • Freshwater ecosystems are strongly affected by human activities on adjacent lands, and protecting these ecosystems must include protection of their watersheds.

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    Freshwater Ecosystems Are under WorldMajor Threats

    • 40% of the world’s rivers have been dammed or otherwise engineered

    • invasive species, pollution , climate change

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    Repeated Invasions by Alien Species in the Great Lakes World

    • 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.

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    Managing River Basins Is Complex Worldand Controversial

    • 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

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    Protect Freshwater Ecosystems by Protecting Watersheds World

    • Freshwater ecosystems protected through

      • Laws

      • Economic incentives

      • Restoration efforts

    • National Wild and Scenic Rivers Act-reestablish protection of rivers

    • Sustainable management of freshwater fishes

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    Priorities for Protecting Biodiversity, Ecosystem Services World

    • 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