Climate alters the migration phenology of coastal marine species

Abstract

Significant shifts in the phenology of life-cycle events have been observed in diverse taxa throughout the global oceans. While the migration phenology of marine fish and invertebrates is expected to be sensitive to climate change, the complex nature of these patterns has made measurement difficult and studies rare. With continuous weekly observations spanning 7 decades in Narragansett Bay, Rhode Island (USA), the University of Rhode Island Graduate School of Oceanography trawl survey provides an unprecedented opportunity to investigate the influence of climate on the migrations of marine species in the northwest Atlantic. Analyses of the survey observations of 12 species indicated that residence periods have changed by as much as 118 d, with shifts in the timing of both ingress to and egress from the coastal zone. The residence periods of warm-water species expanded while those of cold-water species contracted. Dirichlet regressions fit to the annual presence-absence patterns of each species identified interannual temperature variations, fluctuations in ocean circulation, and long-term warming all as having a significant effect on migration phenology. Additionally, temperature gradients within Narragansett Bay were shown by generalized additive models to cause detectable shifts in local spatial distributions during coastal residency. These novel findings mirror results found in the spatial domain and therefore suggest that the studied species are adapting their spatiotemporal distributions to track their thermal niche in a changing climate. If so, characterizing the spatial and temporal aspects of climate responses across species will be critical to understanding ongoing changes in marine ecosystems and successfully managing the fisheries they support.