Potential changes in larval dispersal and alongshore connectivity on the central Chilean coast due to an altered wind climate

Abstract

[1] Climate change is likely to result in significant alterations in the atmospheric and oceanic circulation, which may, as a result, affect species that depend on an ocean-driven nutrient supply and particularly those that possess a dispersal phase in their life history. In this paper we investigate the potential changes in larval dispersal and connectivity of marine populations on the Chilean coast due to altered wind forcing consistent with a future climate change scenario. Numerical ocean simulations forced by modeled present-day and future winds under the Intergovernmental Panel on Climate Change A2 scenario are used to investigate the potential changes in nearshore circulation. Off-line particle-tracking simulations are then analyzed to determine resulting changes in larval dispersal and connectivity under each scenario as a function of pelagic larval duration and for two different possible larval behaviors: passive and vertical migration. It is found that the projected future winds drive an intensification of the upwelling circulation, which results in a relative annual mean surface cooling of 1°C over much of the domain, an increase in the strength of the poleward undercurrent, and a more energetic mesoscale eddy field. Neutrally buoyant larvae are inferred to have low rates of settlement under present conditions and are more strongly disadvantaged under the simulated future conditions than larvae with vertically migrating behavior. Larvae that posses an ability to sink out of the surface Ekman layer are found to have higher rates of settlement under present conditions and are, in fact, favored slightly in the A2 scenario for pelagic larval durations longer than 2 days. This behavior-dependent response to future conditions may potentially drive a reorganization of coastal communities.