Epibiotic bacteria from crustaceans and macroalgae in a subantarctic ecosystem, and their future thermal suitability.

Marine organisms harbor diverse microbial communities on their surface, yet studies exploring the epibiotic bacteria of marine hosts remain largely unexplored, particularly in subantarctic ecosystems. Here, we cultured and isolated bacteria from the surface of three marine hosts: the centolla (the southern king crab; ), a squat lobster (), and a brown macroalgae (), from a subantarctic ecosystem, the Magellan Strait. Bacteria were inoculated in Petri dishes with Thiosulfate-Citrate-Bile Salts-Sucrose (TCBS) agar medium, and a fragment of the grown colonies was used to extract their DNA and sequence the whole 16S rRNA gene. We detected 14 different bacterial taxa, 11 from crustaceans, most of which were found only in the squat lobster. spp. was detected in all marine hosts, but was only detected in crustaceans. Phylogenetic comparisons revealed that epibiotic formed a clade related to environmental species, such as , , and . Given the ongoing climate change the world is experiencing, we explore the future sea surface temperatures that these bacteria might experience in the Magellan Strait. Oceanographic predictions indicate that the maximum sea surface temperatures will be 1 °C warmer in the future decades, and they could reach values above 14 °C in the last decades of the century. Our results increase the distribution and ecology of bacteria and give insights about the temperatures that these microbes will face in future decades, which could have relevant consequences for aquaculture activities.