Using biological effects to determine the impact of exposure to contaminated sediment upon benthic macroinvertebrates

LONG, S.; KELLAR, C.; BALLESTEROS, M.L; ROSE, G.; GOLDING, L.,; GAGLIARDI, B.; PETTIGROVE, V.

Brisbane

Congreso; 2nd SETAC Australasia Conference; 2012

Human activities are a threat to the ecological integrity of many aquatic ecosystems. It is often difficult to isolate the effects of pollutants from other causative factors, and to identify the primary pollutants causing ecosystem stress. Biomarkers can be used to demonstrate that chemicals have been taken up by organisms and exerted a biological effect. The study was undertaken at Lake Hawthorn in northwestern Victoria. Previous surveys showed the presence of pesticides in the sediment at toxic concentrations. The aim of the study was to a) quantify the chemicals present within the lake and b) determine the effects of exposure to sediment‐bound chemicals upon benthic macroinvertebrates using a range of exposure scenarios. The lake was divided into six sampling locations and between three and five sites selected at each location, where sediment and surface water was collected and a range of chemicals were measured (including metals and pesticides). Benthic macroinvertebrates were sampled at each location for species diversity and also for changes at the sub‐organism level for several biomarkers. Sediments were also assessed for effects on survival, growth and emergence of Chironomus tepperi using a laboratory‐based bioassay and impacts on indigenous macroinvertebrates using field‐based microcosms. Chironomid larvae were retained from the laboratory‐based bioassay and microcosms for biomarker measurements. There were elevated concentrations of pesticides, copper and total petroleum hydrocarbons in sediment at an urban inlet drain within the lake. No in situ chironomids were collected at this location; furthermore there were also effects on C. tepperi survival. Biomarker analyses on the chironomid Tanytarsus semibarbitarsus collected in situ showed that chironomids are responding differently within the lake. Our results show that the pollutants present in Lake Hawthorn are toxic to aquatic life. The usefulness of biomarkers in a multiple lines of evidence approach for aquatic biomonitoring will be discussed.