Spatially variable growth responses to warming in Atlantic Sea Scallops (Placopecten magellanicus)

Atlantic sea scallop is an important commercial species in the U.S., and its growth rate is strongly modulated by temperature. In this study, we quantified the interannual variations in scallop growth rate and thermal stress intensity in the Mid-Atlantic Bight (MAB) from 2000 to 2018. The results showed that the scallop growth rate variations were overall synchronized between the shallow (< 60 m) and deep (≥ 60 m) MAB prior to 2015. The response of growth rate to warming in 2015 and 2016 showed marked spatial heterogeneity: scallops in the shallow subregions grew more slowly in the warm years, whereas higher temperature contributed to elevated growth rates in the deep subregions. We developed a dynamic energy budget model to explain the distinct growth rate response to warming at different depths. The model results showed that, in 2016, bottom temperatures in the shallow subregions exceeded the optimal range, limiting the energy available for growth. In contrast, warming created more favorable thermal conditions in the deep habitats. This work reveals the spatiotemporal patterns of scallop growth rates in the MAB and contributes a quantitative understanding of thermal stress and the development of science-based management strategies under future warming.