Gastropod assemblages associated with eight common macroalgae from the hard-bottom subtidal communities near Palmer Station, western Antarctic Peninsula, were investigated in order to establish a species inventory and determine abundance, distribution, and diversity. Four different sites within the area were sampled. Using SCUBA, selected algae were gently removed from the substrate and enclosed in a fine mesh bag. Shortly thereafter, all epibionts were removed and preserved. Twenty-one different gastropod taxa were identified, two of which not to species level. A total of 3486 individuals were quantified with Skenella umbilicata the numerically dominant, followed by Laevilacunaria antarctica and Eatoniella calignosa. Most individuals (86 %) were <0.5-mm shell length; the largest specimens did not exceed 20-mm shell length. No difference in gastropod species abundance or species diversity was observed between the algal species. Mean densities of a given species of gastropod associated with a given algal species ranged from 0 to 38 individuals per 100 g wet wt of sampled alga with no discernable pattern of algal host preference. Additionally, no consistent pattern of gastropod community composition with either associated macroalgal species or collection site was demonstrated with a non-metric multidimensional scaling analysis. Gastropods may, however, work in concert with other epibionts, in particular amphipod assemblages, to in some way benefit the host alga. Specifically, gastropods may contribute to enhancing the photosynthetic capacity of the host alga by grazing upon fouling epiphytic microalgae and emerging endophytic filaments.
