Seasonal variability in macrobenthos assemblage parameters in the highly disturbed Antarctic intertidal zone – Relatively rich biodiversity year around

To understand the impact of anthropogenically induced transformations of biological communities, their naturally occurring fluctuation must be recognized first. Therefore, the aim of this study was to investigate the variability in Antarctic intertidal benthic assemblage faunal composition during an annual cycle (King George Island 62° S). Once a month, from December 2016 to November 2017, samples were collected at low-, mid- and high-tidal levels. Polychaetes were the most speciose group (15 species), followed by amphipods (12). Throughout the year, the most numerous taxa were gastropods (38% of the total number), followed by amphipods (23%) and bivalves (22%). The general pattern of the number of species and their abundance and biomass depended on the season and exhibited the highest values in austral autumn (April–June). Both species richness and abundance were highest in June and lowest in August. This study discovered that Antarctic intertidal macrofauna assemblages quickly respond to changes in environmental conditions and thus reflect seasonal climate fluctuations. The rapid development of these assemblages when the conditions are favourable proves their opportunistic and highly adaptable nature, which is potentially a good prognosis for survival in this ever-changing ecosystem. • Intertidal macrofauna is dominated by gastropods, followed by amphipods and bivalves. • Intertidal assemblages decrease in abundance from lower to higher tidal levels. • In autumn, the intertidal macrofauna was the most diverse and abundant. • Antarctic intertidal fauna quickly respond to natural environmental fluctuations. • The dominant species year around are also most abundant at higher tidal levels.