Larval dispersal and climate models provide insights into present and future distribution of a tropical sardine

Abstract

Climate change impacts the distribution of marine organisms and threatens fisheries. Marine protected areas (MPAs) may buffer the detrimental effects of environmental change by acting as biodiversity spillover to neighboring areas. Yet, it is uncertain whether MPAs on islands favor passive dispersal of species through oceanic currents, and how fish abundance and distribution will be impacted by ongoing global warming. Using the Brazilian-endemic scaled-sardines (Harengula sp.) as model, we implemented a Lagrangian particle-tracking model to estimate dispersal in the Brazilian coast and four MPAs in islands. Then, we projected an ecological niche model (ENM) of Harengula sp. to three climatic scenarios in 2100. Dispersal models suggested that three MPAs in islands export eggs and larvae acting as source of biomass to the coast. ENMs indicated a decrease in environmental suitability for Harengula sp. at the Equatorial Brazilian coast and a southward shift that increases as the climatic scenario is aggravated. Ocean warming may lead to a decrease in suitability for Harengula sp. in the northernmost part of its current distribution concomitant with an increase in offshore zones in the south of its current distribution. Ecosystem disturbance with environmental suitability shifts can aggravate the isolation of populations in islands.