A Black Death: Can Relic Oysters Be Used in Restoration Efforts?

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2018-10-18

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The eastern oyster, Crassostrea virginica, plays an important role in estuarine ecosystems, but populations have been decimated compared to historic levels. Large storm events, including hurricanes, periodically eliminate populations through freshwater input and sediment deposition, leading to death and entombment of shell in sediments. Buried within anoxic sediments, shells turn “black”, and with limited shell for restoration, resource managers have dredged this alternative substrate for larval settlement. Value for “black” shell to facilitate larval recruitment is unknown and this study examined the effectiveness of “black” sun cured shell, freshly removed “black” oyster shell, and normal restoration shell, taking into account background oyster population demographics. Oyster recruitment was significantly greater on sun cured black shell, algal growth on shells was ubiquitous among treatments, and larval recruitment was extremely limited. No significant difference was found from recorded oyster population characteristics, as they were similar to levels after initial construction. This suggests sun cured black shell can be utilized for restoration efforts, but immediate dredging efforts may be impractical. Further, the impact from large storms, such as Hurricane Harvey, can impact settlement substrate and larval supply, thus, resource managers should consider both factors when implementing future restoration efforts.

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