Ecosystem Concepts for Sustainable Bivalve Mariculture (2010) / Chapter Skim
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7 Ecosystem Services of Bivalves: Implications for Restoration
7 Ecosystem Services of Bivalves: Implications for Restoration
Pages 123-132
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From page 123... ...
Traditional approaches to managing environmental resources often failed to recognize the costs of taking those services for granted and allowed development to degrade natural ecosystems and processes in ways that reduce the often substantial value of ecosystem services (Costanza et al., 1997)
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From page 124... ...
. All suspension-feeding bivalves filter particles, including phytoplankton, particulate organic matter, inorganic particles, and planktonic larvae of some marine invertebrates, from the water column and discharge biodeposits, a process that removes phytoplankton and biotic and abiotic particulates from suspension, clarifies the water column, may reduce settlement of some native marine invertebrates, and transfers organic- and nutrient-rich particulates to the bottom (Dame, 1996; Newell, 2004; Dumbauld et al., 2009)
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From page 125... ...
. Because of the importance of SAVs as a nursery habitat for many commercially important fish, crustaceans, and molluscs, the ecosystem services attributable to turbidity reduction by suspension-feeding bivalves include enhancement of an estuarine nursery habitat that itself serves valuable functions in the estuary.
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From page 126... ...
Oysters probably generate greater per capita organic deposition than other bivalve types because of their high filtration rate and capacity to discharge pseudofeces and thereby continue filtration under conditions of high turbidity. In areas of limited flow and long water residence times, biodeposition by dense concentrations of bivalves can be detrimental, causing oxygen depletion in the sediments.
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From page 127... ...
. The benthic invertebrate production together with the provision of structural habitat enhances use of the area by fish and mobile crustaceans by increasing prey availability and providing protection from higher-order predators amid the reef structure (Coen et al., 1999; Lenihan et al., 2001; Peterson et al., 2003; Coen and Grizzle, 2007)
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From page 128... ...
uSE OF MOLLuSCS TO PROMOTE ESTuARINE RESTORATION Wild stocks of bivalve molluscs are susceptible to overexploita tion by fishermen and have generally been depleted from estuaries and coastal oceans worldwide. Bivalve molluscs in soft sediments occupy an essentially two-dimensional bottom habitat; are largely sessile; can often be visually located by some surface clues, such as siphon openings, if not directly in the line of sight of fishermen; and, along with epifaunal bivalves like mussels, are readily accessed by fishermen because of their occupation of shallow or intertidal depths.
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From page 129... ...
. Restoring native oysters can not only bring back an important species toward historical baseline levels but may also restore the filtration functions that improve water quality and enhance resilience of the estuarine ecosystem to eutrophica tion (Jackson et al., 2001a; Lotze et al., 2006)
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From page 130... ...
Natural populations of other oysters do not construct nearly as substantial vertical reefs, in which case mariculture gear may provide more high-relief, structural habitat. However, the introduction of artificial hard substrates often leads to colonization by invasive tunicates and other non native clonal invertebrates, clearly not members of the historical baseline ecosystems.
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From page 131... ...
Because harvest for human consumption of suspension-feeding bivalves requires growing waters that are low in pathogens and pass the standard fecal coliform bacterial assays, it is often tempting to locate mollusc farms near parks, sanctuaries, reserves, and other locations where pollution from stormwater and industrial contamination is minimal. Such locations often coincide with the most valuable wildlife habitats so conflicts between bivalve mariculture and wildlife protection can arise (W�rsig and Gailey, 2002)
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From page 132... ...
Finding: Many estuaries suffer from eutrophication and potentially could benefit from increasing the biomass of suspension-feeding bivalves to provide resilience to eutrophication and reduce the symptoms of excessive nutrient and sediment loading. In addition to limiting effects of eutrophication and sedimentation, restoring the beneficial biogeochemical functioning of suspension-feeding bivalves, especially oysters, could provide additional ecosystem services asso ciated with filtration of phytoplankton and inorganic particles from the water column and deposition of organic biodeposits.
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