Assessment of larval connectivity in a sandy beach mole crab through a coupled bio-oceanographic model

Abstract

The biophysical mechanisms influencing larval distribution and their impacts on the metapopulation dynamics of sandy beaches, particularly the connectivity patterns associated with larval dispersal, are poorly understood. Here, we identify larval connectivity patterns of the mole crab Emerita brasiliensis in the coast of Uruguay. A biophysical individual based model (IBM) of larval transport was coupled to a regional high-resolution physical model to estimate the monthly and interannual variation of larval connectivity, as well as the impact of the length of the reproductive period on it. Larval connectivity showed marked interannual variations, which were mainly related to interannual changes in seasonal winds and associated ocean circulation patterns, particularly during La Niña years. The southernmost area where E. brasiliensis occurs only received larvae from the nearest release area in November and January spawning events during a strong La Niña year, characterized by intense northeasterly winds. The Uruguayan coast constitutes the leading (poleward) edge of the distribution of E. brasiliensis, where climate change effects are projected to intensify. Extrapolation of these results to a climate change scenario with stronger La Niña events, suggest that larval transport to southernmost beaches will become more probable.