For benthic microalgae (microphytobenthos, MPB) community analyses, triplicates of small sediment cores (10 cm length, 3.6 cm diameter) were taken at the stations Faro, Creek and Isla D, respectively, by SCUBA divers during a field campaign to Potter Cove (King George Island, Antarctica) in November and December 2016. Additionally, one larger sediment core (50 cm length, 10 cm diameter), also collected by SCUBA divers, was subsampled for an additional MPB community sample.The upper 0.5 cm sediment layer of a sediment core was transferred into a scintillation vial and 5 mL GF/F filtered seawater (Whatman, UK) and 1 mL of 25% glutaraldehyde was added. The vial was wrapped in parafilm (Bemis Company, USA) and stored at 4°C until analyses in the home laboratory.For the identification and counting of diatoms, diatom valves were cleaned with 30% hydrogen peroxides and mounted in Naphrax after proper rinsing with deionized water (Al-Handal and Wulff, 2008a). Identification of taxa was made following established protocols (Witkowski et al., 2000; Scott and Thomas, 2005; Al-Handal and Wulff, 2008a, 2008b). Enumeration of diatom valves on the slides was made by counting intact valves on the whole slide using Zeiss Axio Image 2 compound microscope equipped with differential interphase contrast under 400-fold magnification. During the identification of taxa, the length and width of pennate valves and the diameter of centric valves were measured using a micrometer. The average length and width of at least 30 valves per taxon and the assumed height of 1 µm (Edler, 1979) were used to calculate the biovolume of diatom cells following Hillebrand et al. (1999) and Sun and Liu (2003). The diatom cell biovolumes were converted into diatom carbon biomass using a conversion factor of 0.089 pg C/ µm³ cell biovolume (Sundbäck et al., 1996). The Shannon-Wiener diversity index H' was calculated using Primer v6.