Variability in site characteristics linked to bay scallop abundance but not tethered survival: Implications for restoration

Abstract

While predation impacts the abundance and distribution of prey species, the overall impact of predation varies with predator identity, predator density, and habitat complexity, among other factors. Numerous commercially and recreationally important prey species, such as bivalves, face intense predation that may affect management and restoration efforts. Therefore, predicting sites with elevated predation risk can be critical for successful restoration, although making predictions based on lab feeding assays may provide challenges. This study used bay scallops Argopecten irradians as a model organism to examine scallop abundance and survival in relation to predator density, habitat complexity, and predicted consumption, across multiple sites within the same estuary. Published predator-specific relationships between scallop consumption and habitat complexity were combined with field survey data to predict consumption potential at six sites in Shinnecock Bay, NY, USA. Using a series of Pearson correlations, the relationships between scallop abundance and tethered survival and site characteristics (habitat complexity, predator density, estimated consumption, scallop recruitment) were explored. Seagrass cover and recruitment of new individuals both strongly influenced scallop abundance, although tethered survival was not strongly correlated to any site metric (predator density, seagrass complexity, or estimated consumption). This study demonstrates potential issues when trying to link mesocosm studies to the field environment, such as sites with no seagrass but potentially confounding habitat complexity (i.e., Crepidula fornicata) and overestimates of consumption due to lack of realism in mesocosm studies. Overall, our study highlights the necessity of conducting field experiments to test mesocosm results, but also provides several valuable conclusions for shellfish restoration.