Impacts of Climate Change Impacts on the Biogeography of three Amnesic Shellfish Toxin-producing Diatom species

Abstract Harmful algal blooms (HABs) are considered one of the main risks for marine ecosystems and human health worldwide. Climate change is projected to induce significant changes to species geographic distribution, and, in this sense, it is paramount to accurately predict how it will affect toxin-producing microalgae. In this context, the present study intends to project the potential biogeographical changes in habitat suitability and occurrence distribution of three key amnesic shellfish toxin (AST)-producing diatom species (i.e., Pseudo-nitzschia australis, P. seriata, and P. fraudulenta) under four different climate change scenarios (i.e., RCP-2.6, 4.5, 6.0, and 8.5) and up to 2050 and 2100. For this purpose, we applied species distribution models (SDMs) using four abiotic predictors (i.e., sea surface temperature, salinity, current velocity, and bathymetry), in a MaxEnt framework. Overall, considerable contraction and potential extirpation was projected for all species at lower latitudes, together with projected poleward expansions into higher latitudes, mainly in the northern hemisphere. The present study aims to contribute to further the knowledge on the impacts of climate change on the biogeography of toxin-producing microalgae species, while at the same time advising towards the correct environmental management of coastal habitats and ecosystems.