The rapid shift of intertidal macroalgal assemblage from vertical shoreline profiles in Barton Peninsula, King George Island, Antarctica during summer

Temporal variability and the vertical shoreline profile of an intertidal macroalgal assemblage were examined on the coast of Barton Peninsula, Maxwell Bay, King George Island, Antarctica. Sampling was performed during the three austral summer seasons from November 2016 to January 2019. The sampling interval for the summer shift was 1–2 months. Eighteen algal species were identified, with 75% relative coverage of the predominant red alga Iridaea cordata and endemic brown alga Phaeurus antarcticus. Temporal variation in the macroalgal assemblage showed 78.35% similarity between one month and 64.61% similarity between two months. Contour plots for visualizing macroalgal distribution were first attempted in this study, and compared to general distribution of tables and diagrams that were discontinuously expressed. The coastscape was expressed more quantitatively and continuously, and was also useful for explaining temporal changes such as summer abundance can be described as a shift from I. cordata to P. antarcticus. In addition, in terms of species composition, this study area corresponds to the middle to lower intertidal zone and shows the highest species diversity in King George Island, so it is expected to provide important information for the researches in Antarctic intertidal zones.