Habitat controls on limno-terrestrial diatom communities of Clearwater Mesa, James Ross Island, Maritime Antarctica

Diatomsare important ecological indicatorsin Antarctica, and paleolimnologists routinely apply transfer functions to fossil diatomsrecovered from lake sediments to reconstruct past environments. However, living diatomcommunities may differ among the possible habitattypes represented in sediment cores (both within lakes and their immediate proximity), hindering the full and accurate interpretation of fossil records. Therefore, an improved understanding of Antarctic diatom habitatpreferences would substantially aid in interpreting regional paleo-material. To gain insights into habitatdifferences, we sampled epipelon, epilithon, Nostocmats, lake-adjacent moss, and wet soil from > 30 lakes and ponds from Clearwater Mesa, James Ross Island, spanning a broad gradient in conductivity (a common basis for transfer functions). We found that diatomcommunities significantly differed between habitattypes (although abundances were too low in Nostocmats to characterize communities), with the clearest distinctions being between submerged (epipelon and epilithon) and exposed (moss and wet soil) groups. Submerged habitattypes had greater abundances of attached aquatic taxa (i.e. Gomphonema spp.), while exposed habitatsharboured more abundant aerophilicgenera (e.g. Hantzschia, Luticola, and Pinnularia). Furthermore, only epilithon communities were significantly related to conductivity, and both epipelon and epilithon habitatsshowed conspicuous increases in Denticula jamesrossensis at greater conductivity values. Collectively, these results improve our knowledge of limno-terrestrial diatomsfrom the Maritime Antarctic Region, and further highlight the utility of incorporating knowledge of habitatpreferences into (paleo)ecological research.