New records and updated distributional patterns of macroalgae from the South Shetland Islands and northern Weddell Sea, Antarctica

This study provides new species records (NRs) of macroalgal assemblages present in rocky habitats from the South Shetland Islands (SSI) and north-eastern Antarctic Peninsula (EAP), Weddell Sea. Surveys were conducted during the summers of 2013/2014 to 2017/2018 at Elephant, Deception, Half Moon and Vega islands. Data from the present study and those available in the literature from the western Antarctic Peninsula (WAP) were combined to provide an updated checklist, giving insights into macroecology and potential changes in thermohaline circulation patterns. A total of 48 macroalgal taxa were identified from our sampling, with eight representing NRs to the EAP sector of the Weddell Sea and five representing NRs to the SSI. Statistical differences among the assemblages from the SSI, WAP and EAP were identified. NRs, including opportunistic species and new information about the biogeographical distributions of species reported here, give insights into ecoregional connectivity and environmental changes. This study updates macroalgal diversity records in regions that are currently experiencing the impacts of climate change. Future and ongoing monitoring for conservation purposes is required to detect non-native species, new dispersal pathways and patterns related to thermohaline anomalies in Antarctic waters.