Marine Protected Areas Tools for Sustaining Ocean Ecosystems (2001) / Chapter Skim
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Conservation Goals
Conservation Goals
Pages 17-29
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From page 17... ...
The discussion that follows highlights some of the differences that may affect application of terrestrial-based models to conserve marine species. Marine and terrestrial ecosystems differ in that marine ecosystems are relatively open, while terrestrial ecosystems have more discrete boundaries.
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From page 18... ...
Marine ecosystems are subject to the physics of the surrounding medium and respond to forces such as tides, circulation patterns, and decadal shifts in overall productivity, whereas terrestrial ecosystems are more internally controlled by the life processes of the dominant organisms (e.g., trees) and may change only slowly, sometimes on century time scales, unless humans intervene (Steele, 1985, 1991, 1996~.
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From page 19... ...
In the marine environment, mobile species such as fish, marine mammals, and sea turtles, move in three dimensions and have a much greater ability to migrate over long distances than is common for organisms in terrestrial ecosystems. This makes it more difficult to identify discrete populations and blurs the apparent boundaries of marine ecosystems.
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From page 20... ...
In the Florida Keys National Marine Sanctuary, less than 0.5% of the sanctuary is closed to all fishing, and most of the other national marine sanctuaries have no areas closed to fisheries. It is difficult to change the perception that access to marine resources is a right because the open-access doctrine has deep roots in the United States.
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From page 21... ...
Marine reserves offer an important if not unique means of protecting marine wilderness for the future use of humanity. Preservation of biodiversity and habitat also has contemporary value because of the ecosystem services provided by natural marine communities.
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From page 22... ...
Preserve or Restore the Viability of Representative Habitats and Ecosystems By preserving representative ecosystems, marine reserves are likely to ensure the conservation of diverse species assemblages and maintain genetic diversity. Although the greater openness of marine systems and the dispersal capabilities of marine organisms help reduce the likelihood of extinction through habitat loss, maintaining the full range of habitat types is necessary for food and shelter to support different stages in the life histories of these organisms and to support ecological processes such as nutrient recycling.
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From page 23... ...
These closures displaced effort to areas with lower fish densities, thereby lowering the catch per day fished (Muraw ski et al., 2000~. The rebuilding plan for these depleted stocks hence reduced the catch both by reducing days at sea and by reducing the efficiency of the fishing effort.
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From page 24... ...
Many economically valuable species have larval or juvenile stages that depend on particular substrates for settlement or on a complex benthic community for certain types of food and shelter from predation. If habitat destruction imperils pre-harvest life stages, then the fishery is threatened by habitat destruction.
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From page 26... ...
Groundfish fisheries suffer because they cannot catch their quotas, and the directed halibut fishery suffers because halibut recruitment is reduced and the biomass of adult halibut killed as bycatch is deducted from the allowable commercial catch. A total annual yield loss of about 11,000 mt was estimated at a time when the halibut directed catch was close to 32,000 mt (Clark and Hare, 1998~.
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From page 27... ...
By relaxing the selection pressure from fishing in some segments of the populations, reserves may help conserve the natural genetic diversity for life-history traits (Trexler and Travis, 2000~. Scientific Knowledge Provide a Source of Baseline Data Marine ecosystems are highly variable associations as a result of both natural variation and anthropogenic effects.
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From page 28... ...
Sustainable Environmental Benefits Marine ecosystems provide benefits beyond harvestable products such as fish and algae. Sometimes referred to as a category of ecosystem services, these benefits include processes such as water purification, protection of coastal areas from storm damage (coral reefs, mangroves, seagrass beds)
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From page 29... ...
. The oldest national marine sanctuary in the United States, for example, was designated to protect the site where the Civil War vessel Monitor sank in 1862.
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