Antarctic and Arctic Seaweeds: Reassessing Diversity, Ecophysiological Adaptations, Connections and Changes in Biogeographical Distribution as a Survival Strategy Facing Meteorological and Oceanographic Changes

Diversity, distribution and biogeographical aspects of polar macroalgae must be reassessed as they face contemporary environmental changes. Macroalgae are the basis of the marine food web, efficient carbon sinks, biogenic habitats and promoters of homeostasis in the oceans. Additionally, algae synthesise bioactive compounds that are used or potentially usable industrially. Algal growth can be limited and sensitive to thermohaline, nutrient, light and pH patterns. Furthermore, as the polar regions drive global climate and oceanographic circulations and as their ecosystems are highly sensitive to changes, their monitoring is essential. In 2012, Wiencke and Amsler published the first compilation of polar macroalgal studies. In this chapter, after a further decade and the intensification of global changes, we revisit this subject, hypothesising that polar biogeographic isolation is being broken, driven by meteorological and oceanographic changes and/or extreme events which alter algal dispersal patterns, resulting in more connected ecosystems. We focus on species richness and diversity, cryptic, cryptogenic and endemic taxa, setting out to reassess the distributions and connections of Antarctic and Arctic seaweed assemblages and species. Current abiotic data are associated with species lists in order to address macroecological aspects, focusing on endemism, ecotones, connections and changes in the biogeographical distribution of these seaweed communities. This data compilation is relevant for the selection of key areas for monitoring in Antarctica and the Arctic that will be fundamental for the identification and interpretation of the impacts of environmental changes on this biota, as well as in supporting conservation actions and advancing polar ocean science.