Sustaining%20Aquatic%20Biodiversity

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Sustaining Aquatic Biodiversity

• Chapter 11

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11-1 What Are the Major Threats to Aquatic
Biodiversity?

• 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.

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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.

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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
  rivers/lakes

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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

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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

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Overfishing and Extinction Gone Fishing, Fish
Gone

• 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
  continue

• Bycatch organisms caught unintentionally in
  nets
• We throw away 30 of the fish we catch.

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

• 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.

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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 fishprint are
  expanding
• 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

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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

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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
  1986.
• Annual harvest dropped from 42,000 to 1,300
• Whale populations have rebounded so much that
  some countries are contemplating hunting again.

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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
  treaties

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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.

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11-3 How Should We Manage and Sustain Marine
Fisheries?

• 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.

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11-3 How Should We Manage and Sustain Marine
Fisheries?

• 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.