These studies are typically conducted in the receiving environment, and involve sampling different components to determine the potential for exposure, as well as adverse effects. Nautilus is well-known for implementing study designs that incorporate ecological components and exposure metrics in a manner that facilitates rigorous identification of linkages between contaminants of concern and potential for adverse effects. Selected examples include:
Evaluation of potential sublethal effects in Dungeness crab and English sole associated with a municipal wastewater discharge. Response parameters included whole organism, tissue and biochemical metrics, which were evaluated in the context of sediment contaminant concentrations. Differences between organisms from exposure and reference sites were considered potential evidence of impacts, and statistical linkages with particular contaminant groups were used to identify potential contaminants of concern.
A combination of benthic macroinverebrate and fish surveys, salmonid in situ early life stage deployments, toxicity testing and contaminant analyses were used to characterize the potential extent and magnitude of impacts associated with a mine discharge; based on detailed comparisons between upstream and downstream reaches, no impacts were present downstream of the discharge.
Pulp and Paper Discharge
The potential impacts of a discharge from a pulp and paper mill discharge on an estuarine benthic invertebrate community were evaluated using a study design that incorporated depth and salinity gradients. Interestingly, both salinity and depth were found to be significantly affect community structure, but no adverse effects were associated with the discharge.
In response to an oil spill in a tidal marsh, sediment samples were analyzed for contaminants of concern and toxicity. Collectively, the data were used to establish the presence, magnitude, and extent of impacts, and guide the remediation process.
The potential effects of surfacing contaminated groundwater on an intertidal invertebrate community was evaluated using a combination of toxicity tests, analytical data and biological community analysis. Although the evaluation was complicated by the nearby presence of a stormwater outfall, toxicity tests conducted on the groundwater indicated that no toxicity should be apparent in the receiving environment; this finding was confirmed by an evaluation of community composition and age structure of key receptors.