Marine heatwaves and changes in macroalgae richness and composition from Antarctic Peninsula and South Shetland...

The emerging global events of Marine Heatwaves (MHW), including those in Antarctica, are generally caused by large-scale meteorological and oceanographic changes responsible for rapid warming, but with lasting consequences in marine communities worldwide. Several abiotic features, such as surface seawater temperature (SST), salinity, pH, nutrients, and ice dynamic limit the reproduction, growth and distribution of macroalgae, which are sensitive to abrupt oscillations in these features resulting in changes in polar assemblages. This review compiled and related MHWs spatial data from South Shetland Islands (SSI), Eastern and Western Antarctic Peninsula (EAP/WAP), discussing seaweed assemblages possible responses on composition, distribution and richness, as well species expansion and retreat. Additionally, we present an updated and compiled checklist of macroalgal taxa from the WAP. The present data showed a clear enhance in MHWs events in SSI, when compared to EAP and WAP. Also, this coincides with the increase in richness and distributional changes of seaweed assemblages along the SSI, in the last decade. Changes in these marine sentinel assemblages constitute a warning to the Antarctic biota. Besides, the present review expands current polar knowledge and detects gaps in Antarctic phycological conservation studies and their connections facing climate change.