The Effects of a Small Sewage Outfall on an Algal Epifaunal Community at Macquarie Island (sub-Antarctic): A Drop in the Southern Ocean?

Macquarie Island, in the sub-Antarctic, is the location of one of four permanently staffed bases operated by the Australian Antarctic Division. As part of a wider programme investigating the effects of human presence on Antarctic and sub-Antarctic ecosystems, this study evaluated the impact of the small sewage outfall at Macquarie Island on the epifauna living within turfs of the intertidal red alga Chaetangium fastigiatum. Sampling was conducted during early December (austral summer) in both 1996 and 1997 at six sites, two sites within each of three adjacent bays. The site closest to the outfall was 3 m from the point of discharge. Data analyses at the population and community levels failed to demonstrate a significant effect of the outfall. Small scale spatial patterns, probably related to wave exposure, and inter-annual variation in recruitment, are suggested as the main causes of variation in patterns of epifaunal dominance during the study.