Epibiotic relationships in the Antarctic benthos

Abstract

On the high Antarctic shelf, 374 different epibiotic relationships of the megafauna were photographically registered and statistically analysed. These comprised 47 different epibiotic and 96 substratum taxa and had obvious differences in abundance and presence in three different benthic assemblages. Six abundant obligatory relationships in which the epibiont occurred almost exclusively on one type of substratum had highly specialized epibionts. For an additional eight relationships, a statistical test revealed that the epibionts preferred specific living and elevated mineral substrata. Most of these relationships are interpreted as commensalism (sensu Odum) in which the suspension feeding epibiont profits from the elevated position. Here it has better access to food compared with life on the sediment. The evolution of a rich and mainly sessile epifauna on parts of the high Antarctic shelves and the successful development of epibiotic behaviour in other species are suggested as a major reason for the high species richness in the benthic fauna. The results provide evidence that the Antarctic megabenthos is more biologically accommodated than physically controlled.