Diversity and habitat preferences of benthic diatoms from South Bay (Livingston Island, Antarctica)

Background and aims – Despite a long research history, knowledge of Antarctic marine benthic diatoms is fragmentary. This study reports on marine benthic diatoms from South Bay, Livingston Island, focusing on diatoms living on hard substrata, and species distribution across different coastal habitats.Material and methods – Samples were collected from tidal pools (19), intertidal cobbles (9), artificial substrata installed at various depths (10), coastal rocks (2), and bottom sediments at depths > 20 m (2). Species identifications and community analyses were done using LM with additional information obtained using SEM. nMDS based on diatom abundance data was applied to display differences between the samples by habitat/substratum type and sampling month. The significance of the habitat/substratum type and sampling month on diatom communities was checked with PERMANOVA. Similarity/dissimilarity within and between sample groups and their contributing species were explored with SIMPER.Key results – In total, 133 diatom taxa were recorded, of which 110 are benthic. A large number of taxa could not be certainly identified. Taxonomic remarks and ecology and distribution data for some rarely reported species with convoluted taxonomic and nomenclatural histories are given. One new combination is proposed. Diatom communities were influenced by the habitat/substratum type, but not by seasonality. Significant differences existed between communities in tidal pools and those on cobbles, artificial substrata, and sediments, and between those on sediments and artificial substrata. Navicula aff. perminuta dominated on cobbles and often on artificial substrata. Species forming mucilage tubes, tree-like colonies, and chains of cells embedded in mucilage were restricted to tidal pools.Conclusion – Benthic diatom communities from South Bay are highly diverse and species show distinct distributions in the coastal habitats, but the scarce studies and often confusing nomenclature history of the taxa make their identification challenging, and potentially common species for the region remain unknown.