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Title: Sustaining%20Aquatic%20Biodiversity


1
Sustaining Aquatic Biodiversity
  • Chapter 11

2
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.

3
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.

4
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

5
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

6
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

7
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.

8
Major Commercial Fishing Methods Used to Harvest
Various Marine Species
Trawler damage
9
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.

10
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

11
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

12
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.

13
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

14
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.

15
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.

16
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.
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