Meiofaunal communities and human impacts at Casey Station, Antarctica

Marine benthic communities, including meiofauna, have commonly been used as a focus of monitoring programs and of research into the effects of human activities in the marine environment. In Antarctica, benthic communities have been shown to be good indicators of human impacts, however, there is very limited information on Antarctic meiofaunal communities and how they may respond to anthropogenic disturbances. The main types of contamination present in marine sediments around Antarctic stations are metals and hydrocarbons. A survey of sediment meiofaunal communities was done at Casey Station, Antarctica, with sampling at a range of spatial scales, from 10 meters to kilometers, to determine the spatial patterns of community composition and abundance. This included a comparison of control and disturbed areas (adjacent to old waste disposal sites). An MDS of all 47 samples supported by one way ANOSIM (Global R= 0.955, P< 0.001) showed the variation within locations was less than the variation between locations (kms) and significantly different between control and polluted locations. From the total meiofauna, a higher percentage of nematodes, by comparison to harpacticoid copepods in both controlled (nematode, 94.8%: harpacticoid copepods, 5.2%) and disturbed locations (nematode, 95.4%: harpacticoid copepods, 4.6%). Multivariate biological (meiofaunal communities) and environmental datasets were examined to determine whether there were any correlations between patterns of community composition and environmental variables. The analysis suggested that the most influential variables on the community pattern were metals of anthropogenic origin such as tin, lead, iron, copper, and zinc but also metals that probably relate to local differences in mineralogy such as silver, barium, uranium and arsenic. Grain size parameters were found to have a much lower capacity to explain differences in meiofaunal communities, although there did appear to be some influence. An experiment was setup in which four different hydrocarbons (SAB diesel fuel, and clean, used and biodegradable lubricant oils) were added to defaunated marine sediments and deployed in trays in a sheltered marine bay. The communities colonizing the sediments were monitored for up to five years. The effects of hydrocarbon contamination on meiofaunal communities were different for each type of hydrocarbon. The Control and Biodegradable treatments had the most similar meiofaunal communities at all sampling times. Effects of hydrocarbon treatments were still evident after five years. Results also suggest that changes in nematode composition are ideal for long term pollution monitoring. By comparison, copepods appeared to be less sensitive to hydrocarbon pollution. Long-term monitoring is essential to understand the true extent to which lubricants impact the community structure.