Contamination in estuaries: new approaches to measuring ecological impacts

Estuaries are considered some of the most degraded aquatic habitats worldwide and in Victoria the majority are affected by human activities to some degree. Contamination from urban sources is a common cause of degradation yet... [ view full abstract ]

Estuaries are considered some of the most degraded aquatic habitats worldwide and in Victoria the majority are affected by human activities to some degree. Contamination from urban sources is a common cause of degradation yet there are few validated techniques and ‘tools’ available to assess the ecological impacts of contaminants in Australian estuaries. The overall goal of our research is to combine different approaches (both field and laboratory experiments measuring a range of responses) as a suite of tools to assess the ecological impacts of contamination in any estuary. We will present results from field experiments using in situ mesocosms and sediment dosing laboratory experiments. Promising results from the first multiple-estuary trial of a field mesocosm approach demonstrated that the mesocosms could be used to identify macroinvertebrate community responses to sediments from estuaries with different background levels of contamination. We will highlight key results that show community patterns that occur over multiple spatial and temporal scales. Our recent laboratory experiments focused on individual responses to copper-dosed sediments, using the amphipod Gammaropsis sp. as a model species and investigated concentrations of copper that affect amphipod behaviour and survival. We also assessed the effects of copper concentration on chlorophyll biomass and a measure of microbial functional diversity and possible connections with amphipod responses. Future directions for our research include expanding the range of endpoints measured in laboratory experiments and using mesocosms with sediments dosed with copper and other contaminants to identify specific relationships between contaminants and biological communities. We expect the combination of results from similar contaminant-dosing experiments in the field and laboratory will progress understanding of how such experiments are relevant to real environmental conditions.