Ecosystem Concepts for Sustainable Bivalve Mariculture (2010) / Chapter Skim
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1 Introduction
1 Introduction
Pages 17-28
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From page 17... ...
The recognition that, even in developed countries with professional fish eries managers, wild-stock fish, shellfish, and bivalve molluscs have not always been sustainably harvested (e.g., Jackson et al., 2001a; Lotze et al., 2006) leads to concerns over how coastal policies can facilitate expand ing mariculture to meet rising demand while management is conducted in a way to preserve ecosystem integrity and sustainability.
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From page 18... ...
The committee conducted a review to characterize the vari ous types of bivalve mariculture operations and the processes through which they have potential to affect the structure and function of the natural ecosystem. The uncertainties associated with these potential ecosystem impacts are identified, along with suggestions on research needs that could help reduce uncertainty and lead toward development and imple mentation of spatially explicit ecosystem-based mariculture planning that could enhance benefits and minimize negative impacts.
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From page 19... ...
Of Paine's three basic web categories, descriptive food webs and energy flow webs are essentially illustrative of structure. Only interaction webs focus on how particular linkages within the web's topology drive or
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From page 20... ...
The habitat services provided by mariculture of Pacific oysters may differ from those provided by native Olympia oysters because the native oyster does not form extensive tall reefs, even where abundant, whereas the rack structures holding strings of cultured Pacific oysters extend about 1 m upwards from the bottom and provide hard-substrate habitat for a nonnative tunicate that covers a substantial portion of the rack and oyster surfaces. The biogeochemical effects of the cultured nonnative oysters, as distin guished from the impacts of mariculturists' activities, are likely to be small as long as the level of production is low relative to the ecological carrying capacity of the ecosystem.
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From page 21... ...
However, a question more relevant to the expanded spatial scales characteristic of most mariculture operations is whether the interactions defined and demonstrated at smaller scales can be scaled up and also applied at the level of an estuary or even an open ecosystem. Two primary lessons derived from the outcomes of these experimental studies can be applied to the management of bivalve mariculture.
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From page 22... ...
On the other hand, the benthic food web has flourished, in large part because of clearer water, enhanced growth of submerged macrophytes, and increased densities of both nearshore invertebrates and fish. Indirect effects are apparent.
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From page 23... ...
The relationship between water rights law, California agriculture, Chinook salmon production, and the Endangered Species Act represents a regulatory quagmire. While bivalve mariculture is not involved, the sweeping consequences to a diverse stakeholder assemblage attributed to a dominant and introduced suspension feeder are obvi ous.
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From page 24... ...
The implications for intensive, local development of bivalve mariculture seem obvious -- ecosystem impacts can be anticipated although many of them may not be immediately apparent and cannot be predicted with the certainty that stakeholders often demand from resource managers and decision makers. Assessing whether anticipated modifications of the estuarine ecosystem are beneficial or detrimental depends in part on knowledge of historical baselines of bivalve abundance and a synthesis of the net value of direct and indirect impacts.
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From page 25... ...
The bivalve species can be subdivided by aquatic environmental regime in which they live (ocean versus estuary versus marine lagoon) , relationship to substrate (epifauna on the surface of the hard substrate versus infauna buried within the soft substrate)
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From page 26... ...
Although the concept of carrying capacity is generally understood, there are numerous alternative bases on which to set the carrying capacity for molluscan mariculture, each with different implications for management. The strict application of the logistic growth curve to stocking of suspension-feeding bivalves would lead to a hydrographically defined water body in which individual bivalve seed would become stunted in growth because of exhaustion of the resources required for growth.
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From page 27... ...
Many stakeholders will provide social input that reflects an environmen talist commitment to sustaining ecological integrity, such that this consideration will contribute to determining social carrying capacity. REPORT ORGANIZATION This report is organized to review the challenges, constraints, and benefits of maintaining or restoring ecosystem integrity in the presence of bivalve mariculture.
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