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Sustaining Aquatic Biodiversity Chapter 11 * 11-1 What Are the Major Threats to Aquatic Biodiversity? Concept 11-1 Aquatic species are threatened by habitat loss ... – PowerPoint PPT presentation

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Title: Sustaining%20Aquatic%20Biodiversity

Sustaining Aquatic Biodiversity
  • Chapter 11

11-1 What Are the Major Threats to Aquatic
  • Concept 11-1 Aquatic species are threatened by
    habitat loss, invasive species, pollution,
    climate change, and overexploitation, all made
    worse by the growth of the human population.

We Have Much to Learn about Aquatic Biodiversity
  • We know fairly little about the biodiversity of
    the worlds 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 bottom
    because of habitat and food source variety.

Human Activities Are Destroying and Degrading
Aquatic Habitats
  • Just remember H.I.P.P.C.O.!!
  • Habitat destruction
  • Human activities have destroyed, disrupted or
    degraded a large proportion of the worlds
    coastal, marine and freshwater ecosystems.
  • Approximately 20 of the world's coral reefs have
    been destroyed.
  • We have destroyed more than 1/3 of the worlds
    mangrove forests for shipping lanes.
  • Freshwater aquatic zones are also affected
  • Dams and excessive water withdrawal from

Invasive Species, Population Growth, and
Pollution Can Reduce Aquatic Biodiversity
  • 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 worlds Population lives on or
    near a coastal zone and 80 of ocean water.
  • Pollution comes from land-based human activities.
  • Nitrates and phosphates mainly from fertilizers
    enter water
  • Leads to eutrophication
  • Toxic pollutants from industrial and urban areas

Climate Change Is a Growing Threat
  • Climate change as a result of global warming will
    cause sea levels to rise and aquatic biodiversity
    to be threatened.
  • Water too warm for coral reefs
  • Swamp some low-lying islands
  • Drown many highly productive coastal wetlands

Overfishing and Extinction Gone Fishing, Fish
  • Overfishing
  • About 75 of the worlds commercially valuable
    marine fish species are overfished or fished near
    their sustainable limits.
  • Big fish are becoming scarce.
  • Smaller fish are next.
  • Commercial extinction
  • so few exist that it is no longer profitable to
  • Bycatch organisms caught unintentionally in
  • We throw away 30 of the fish we catch.

Major Commercial Fishing Methods Used to Harvest
Various Marine Species
Trawler damage
11-2 How Can We Protect and Sustain Marine
  • Concept 11-2 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.

Legal Protection of Some Endangered and
Threatened Marine Species
  • Why is it hard to protect marine biodiversity?
  • Human ecological footprint and fishprint are
  • Much of the damage in the ocean is not visible
  • The oceans are incorrectly viewed as an
    inexhaustible resource
  • Most of the ocean lies outside the legal
    jurisdiction of any country

Legal Protection of Some Endangered and
Threatened Marine Species
  • Laws, international treaties, and education can
    help reduce the extinction of marine species.
  • CITIES, ESA, etc.
  • Since 1989 the U.S. government has required
    shrimp trawlers to use turtle exclusion devices.
  • Sea turtle tourism brings in almost three times
    as much money as the sale of turtle products.
  • Dolphin Safe tuna

Case Study Protecting Whales A Success Story
So Far
  • International Whaling Commission (IWC)
  • After many of the worlds whale species were
    overharvested, commercial whaling was banned in
  • Annual harvest dropped from 42,000 to 1,300
  • Whale populations have rebounded so much that
    some countries are contemplating hunting again.

Marine Sanctuaries Protect Ecosystems and Species
  • Exclusive economic zones
  • A countrys offshore fishing zone extends 200
    miles from the shore
  • This area is under their jurisdiction and is
    their responsibility
  • High seas beyond legal jurisdiction
  • Difficult to monitor and enforce international

Establishing a Global Network of Marine
ReservesAn Ecosystem Approach
  • Marine reserves areas of the ocean that are
    closed to commercial fishing, dredging, mining
    and waste disposal
  • Less harmful activities allowed
  • E.g., recreational boating and shipping
  • Fully protected marine reserves make up less than
    0.3 of the worlds ocean area.
  • Studies show that fish populations double, size
    grows by 30, reproduction triples, and species
    diversity increases by 25.
  • Integrated Coastal Management conservation
    efforts and methods need to customized to the
    specific region/ecosystem being protected.

11-3 How Should We Manage and Sustain Marine
  • Concept 11-3 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.

11-3 How Should We Manage and Sustain Marine
  • Maximum sustained yield (MSY)
  • The maximum that can be harvested without causing
    a population drop
  • Optimum sustained yield (OSY)
  • Recalculates MSY taking into account the
    interactions with other species and allows for
    more room for error.