Cooperative Fish and Wildlife Research Units Program: Louisiana
Education, Research and Technical Assistance for Managing Our Natural Resources

Lavaud R, La Peyre MK, Couvillion B, Beseres Pollack J, Brown V, Palmer T, Keim B. Predicting restoration and aquaculture potential of an ecological engineer through an eco-physiological mechanistic model. Ecological Modeling


A simple, non-negotiable truth of ensuring success in restoration of ecological engineers (EE) and the functions they support remains the need for the focal species to survive, grow and reproduce. The use of mechanistic modeling, such as a dynamic energy budget (DEB), to map an EE’s fundamental niche provides supports restoration and management predictive of EE resilience under current and future conditions. One EE, the eastern oyster, Crassostrea virginica, provides critical estuarine habitat, and supports a valuable fishery across the northern Gulf of Mexico. Recent declines in oyster populations in this region from human activities, as well as short-term and extreme events have led to significant efforts to restore wild, self-sustaining broodstock reefs, and develop off-bottom aquaculture. To explore potential outcomes for oyster restoration and aquaculture development, we used an individual bioenergetic model based on DEB theory to derive an aquaculture index, based on survival and time to market size, and restoration index, based on survival and reproductive output, across six key Texas and Louisiana estuaries under current (2014–2020) and future predicted environmental conditions (2041–2050). Aquaculture scores using daily averaged current conditions reproduce an observed gradient of oyster growth success increasing from upper estuary to offshore areas, with lower variation in Texas estuaries compared to Louisiana. Restoration scores under daily averaged current conditions showed similar trends with more variability than the aquaculture index due to spawning potential, which is of importance for reef sustainability. In general, Louisiana estuaries showed higher growth rates, and reproduction compared to Texas estuaries, but due to the higher variability and more frequent extremes in salinity and temperature, Louisiana estuaries were more likely to experience mortal conditions any given year, as compared to Texas estuaries. Comparison between current and future conditions indicated that oyster aquaculture and restoration potential in presently occupied areas will possibly decrease in a future climate. However, the spatial resolution of currently available climate model outputs within coastal and estuarine areas limits planning information. This represent a necessary area of improvement to better evaluate the physiological response of EE to future conditions, especially since most aquaculture and restoration developments are likely to occur close to the coastline. Finally, this work demonstrates the potential of mechanistic modeling to inform future planning under environmental conditions likely not currently within the realized niche of EE.