Simulated larvae dispersion of the invasive sun-coral (Tubastrea spp.) along Rio de Janeiro's coast: the role of submesoscale filaments on offshore transport and connectivity

The spread of invasive species in marine ecosystems is a growing global concern, particularly in regions with high economic and ecological importance. sun corals (Tubastraea spp.) are scleractinians native to the Pacific Ocean that have spread along most of the Brazilian coast. This exotic species initially established populations in Rio de Janeiro, reaching high levels of abundance. Although the ecological aspects and impacts caused by this organism have been studied in detail, the natural mechanisms that drive its dispersal have attracted little attention. In this research, we focus on the offshore transport of sun coral larvae between Cabo de Sao Tome and Ilha Grande Bay, RJ, investigating how submesoscale oceanographic features such as filaments, eddies and upwelling influence connectivity among different population. High-resolution numerical simulations were used to model the coastal dynamics, incorporating the influence of the Brazil Current, wind-driven circulation, and submesoscale structures. Larval dispersal was examined under different wind scenarios, including northeasterly winds that drive southward currents which enhance offshore transport via submesoscale filaments. Results show that submesoscale features, particularly filaments emerged from upwelling regions, play a significant role on sun coral larvae dispersion. These features act as pathways that connect larvae from coastal to offshore oil exploration areas, highlighting the importance of both natural and anthropogenic processes for the dissemination of this invasive species. This research provides critical insights into the ecological mechanisms governing the spread of invasive marine species, emphasizing the need for integrated coastal management strategies. Understanding how physical processes drive larval transport is essential for developing targeted control measures to mitigate the impact of invasive species like sun coral on native ecosystems and local economies. Furthermore, the study underscores the importance of monitoring both natural and anthropogenic influences on marine bioinvasions, particularly in regions with significant offshore industrial activities.