Defining oyster resource zones across coastal Louisiana for restoration and aquaculture

Lauren M. Swam; Brady Couvillion; Brian Callam; Jerome F. La Peyre; Megan K. La Peyre

doi:10.1016/j.ocecoaman.2022.106178

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Defining oyster resource zones across coastal Louisiana for restoration and aquaculture

Lauren M. Swam·Brady Couvillion·Brian Callam·Jerome F. La Peyre·Megan K. La Peyre

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Abstract

Eastern oysters ( Crassostrea virginica ) are a critical ecological and commercial resource in the northern Gulf of Mexico facing changing environmental conditions from river management and climate change. In Louisiana, USA, development of restored reefs, and off-bottom aquaculture would benefit from the identification of locations supportive of sustainable oyster populations ( i.e., metapopulations) and high consistent production. This study defines four oyster resource zones across coastal Louisiana based on environmental conditions known to affect oyster survival, growth, and reproduction. Daily data from 2015 to 2019 were interpolated to generate salinity and temperature profiles across Louisiana's estuaries, which were then used to classify zones based on monthly and annual salinity mean and variance. Zones were classified as supportive of (1) broodstock sanctuary reefs (i.e., support reproductive populations), (2) productive reefs during dry (salty) years, (3) productive reefs during wet (fresh) years, and (4) off-bottom aquaculture development. Of the 38,000 km 2 investigated, over 11,000 km 2 of potential oyster zone area was identified across the Louisiana coast. The Broodstock Sanctuary Zone was the smallest (∼540 km 2 ), as salinity variance limited this zone in many areas, as it is driven largely by riverine inputs across many estuaries. Located up-estuary (Dry Restoration Zone) and down-estuary (Wet Restoration Zone) of the Broodstock Sanctuary Zone, Dry and Wet Restoration Zone areas covered ∼2400 km 2 and ∼3900 km 2 , respectively. Mapped reefs in Louisiana currently exist largely within the Dry Restoration zones, suggesting a potential strategy to focus reef development in Wet Restoration zones to ensure reef network sustainability through years with high precipitation and river inflow. The off-bottom Aquaculture Zone was the largest (∼6400 km 2 ) zone identified, with much of this area located more down-estuary and off-shore. Accounting for variable water quality conditions enables the development of a network of reefs resilient to environmental variability, and more stable areas for consistent off-bottom aquaculture production. Spatial planning and identification of oyster resource zones reduces focus on individual reef success and supports management of oyster metapopulation outcomes, while identifying zones supportive of off-bottom aquaculture.

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Ocean and Coastal Management Article

Source-reported bounding extent: 28.980943971169282° to 30.512183704575193° latitude; -93.94164092204788° to -88.89450433276538° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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Lauren M. Swam, Brady Couvillion, Brian Callam, Jerome F. La Peyre, Megan K. La Peyre. 2022. Defining oyster resource zones across coastal Louisiana for restoration and aquaculture. https://doi.org/10.1016/j.ocecoaman.2022.106178

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