Benthic foraminifera and trace metals in sediments off the Scott Base sewer outfall, Antarctica / Bruce Anderson and Catherine Chagué-Goff.

"Nov. 96"--Cover.

Includes 29 bibliographical references (p. 30-32); 13 figs; 7 tables.

A preliminary survey was conducted in November-December 1994 in order to ascertain possible effects of effluent discharge from Scott Base on the benthic fauna. Scott Base is the New Zealand Antarctic Programme's only permanently staffed base in Antarctica located on Pram Point, Ross Island. Base occupancy rates were between 12-48 people during November-December 1994. Macerated sewage and wastewater from Scott Base are discharged into McMurdo Sound. Sediment, sewage and wastewater samples were collected and analysed fro trace metals. Spatial distribution and assemblage composition of benthic foraminifera in the region centred on the sewage outfall were examined. Current velocities and directions were recorded at selected sites. Elevated levels of contaminants are reported in the effluent (1379 ppb Cu, 24 ppb Pb, 3693 ppb Zn, 20 ppb Ni) and in the sediment at the sewage outfall outlet (2754000 ppb (0.275%) Cu, 91200 ppb Pb, 462200 ppb Zn). Sediment contamination is mainly restricted to the area at closest proximity to the sewage outlet. Cu and Zn concentrations exceed and Pb concentrations nearly reach the levels above which toxic effects on marine biota occur frequently. Twenty-eight benthic foraminifera species were identified in sediment off Pram Point. The populations were dominated by the five species #Ehrenbergina glabra, Cribrostomoides jeffreysii, Trifarina earlandi, Cassidulinoides porrectus and Rosalina globularis#. This association of five species forms between 79 - 92% of total specimens. At sites close to the sewer outfall foraminifera assemblages varied considerably. The site closest to the outfall contained no foraminifera in 34 g of sediment but contained high numbers of ostracoda. At the next closest sites different assemblages were recorded, with a reduction in number of #E. glabra#. This altered assemblage is interpreted as resulting from effluent discharge. Distant sites showed only minor variations in assemblage composition. A second near barren sample was collected from the area of the reverse osmosis water intake / brine return. Spatial variations in foraminifera assemblages off Pram Point are likely to be caused by changes in environmental conditions related to effluent discharge. (auths)