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Understanding Marine Biodiversity (1995) / Chapter Skim
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3 BIODIVERSITY CHANGES DUE TO ANTHROPOGENIC EFFECTS: CRITICAL ENVIRONMENTAL ISSUES
Pages 24-34

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From page 24...
... Natural perturbations have always occurred in the oceans ranging from seasonal climatic events (such as hurricanes, typhoons, and storm tides) leading to local habitat destruction, to E1 Nino-Southern Oscillation events, to natural oil seeps but the resulting changes in biodiversity were frequently reversible or have been long integrated into the larger spatial and temporal patterns of ecosystem structure and function.
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From page 25...
... However, it will not always be possible to separate longterm natural variation or cyclic changes from human impacts and the potentially large synergistic interactions between them. The ubiquity and magnitude of human perturbations have already reduced and in some areas eliminated opportunities to study pristine habitats or communities within habitats.
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From page 27...
... The native oyster Crassostrea virginica once supported an enormous; fishery that began to show significant declines a century ago due to overfishing and associated activities (such as the nonreplacemer~t of shell for larval oysters to settle upon)
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From page 28...
... Even with management practices now in place, fisheries have major impacts on ocean environments, ranging from direct harvest to by-catch effects, habitat destruction, genetic changes, and food web changes. The challenge is to pursue a balanced view that incorporates ecological considerations and societal needs that is, for longterm sustainable use of marine organisms for food and other products.
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From page 29...
... , and ancillary impacts on interacting species or ecosystem effects. In the eastern tropical Pacific, tuna purse seine fisheries began in the late 1950s and incidentally encircled dolphins to capture the yellowfin tuna schools typically found underneath them.
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From page 30...
... Mariculture in the form of sea-ranching can reduce the genetic diversity of a species if the individuals in cultivation begin to contribute substantially to the gene pool of the wild population (that is, through external fertilization between gametes from cultivated and wild members of the species EMork, 1991; Gharrett and Smoker, 199311. Mariculture also has the potential to subject wild populations to an increased incidence of disease because of the well-known susceptibility of large, homogeneous populations (Lannan et al., 1989; Padhi and Mandal, 1994~.
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From page 31...
... , mining wastes, fuel ash, and radioactive materials are among the primary marine pollutants (Hughes and Goodall, 1992~. An increased incidence of tumors and diseases in fish is one of the many consequences of contamination of estuarine and coastal environments by this broad range of pollutants (Myers et al., 1991; McCain et al., 1992; Vethaak and Rheinaldt, 1992~.
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From page 32...
... Box 7 focuses on biological invasions via ballast-water transport, and a specific example of ecosystem-level effects of a ballast-water invasion was given in Box 6. The extent to which exotic invasions have affected the pelagic ocean, the coastal shelf, and tropical ecosystems such as coral reefs is largely unknown because of a lack of baseline information on the composition of these communities and a lack of studies focused specifically on invasions.
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From page 33...
... BlODIVERSITY CHANGES DUE TO ANTHROPOGENIC EFFECTS 33 ~ ~ at: ~ i In .
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From page 34...
... A warming Earth could affect the sea, from the most inland marshes to the deepest oceans, in predicted ways that range from sea-level rise to modified patterns of rainfall and oceanic circulation (which, in turn, would affect nutrient supply and distribution)
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Key Terms

  • ballast water
  • human perturbations
  • synergistic interactions
  • fish populations
  • critical environmental

  • sea urchins
  • phytoplankton blooms
  • coral reefs
  • affect biodiversity
  • sea urchin

  • cascading effects
  • nearshore habitats
  • ecosystem structure
  • marine mammals
  • habitat destruction

  • interacting species
  • potential genetic
  • marine pollutants
  • marine habitats
  • food web

  • herbivorous fish
  • energy flow
  • nontarget species
  • associated activities
  • human stresses

  • curio trade
  • estuarine habitat
  • homogeneous populations
  • compounds rising
  • primary marine


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