Carolin Dahms, Shaun S Killen

The current effects of global warming on marine ecosystems are predicted to increase, with species responding by changing their spatial distributions. Marine ectotherms such as fish experience elevated distribution shifts, as temperature plays a key role in physiological functions and delineating population ranges through thermal constraints. Distributional response predictions necessary for population management have been complicated by high heterogeneity in magnitude and direction of movements, which may be explained by both biological as well as methodological study differences. To date, however, there has been no comprehensive synthesis of the interacting ecological factors influencing fish distributions in response to climate change and the confounding methodological factors that can affect their estimation. In this study we analyzed published studies meeting criteria of reporting range shift responses to global warming in 115 taxa spanning all major oceanic regions, totaling 569 three-dimensional population responses (latitudinal, longitudinal and depth), with temperature identified as a significant driver. Overall, studies on marine fish distributional responses have generally been of limited spatial and temporal scope, with comparisons among studies being complicated by large variation in methodology. We identified varying degrees of heterogeneity in latitudinal range shifts (km year-1) across ecological and methodological predictors, with multivariate regression analysis revealing response rate differences due to niche affinity, depth changes, as well as methodological biases due to different approaches in estimating and reporting latitudinal range shifts. Finally, we found strong geographical publication bias and limited taxonomical scope, highlighting the need for more representative and standardized research in order to address heterogeneity in distribution responses and improve predictions in face of changing climate.