A non-lethal chemically based approach to investigate the quality of harbour sediments

A non-lethal chemically based approach was used to investigate the quality of harbour sediments receiving combined road runoff and sewage effluents. A previous investigation of the behaviour of the amphipod Corophium volutator linked polycyclic aromatic hydrocarbons (PAH) in sediments corresponding to the probable effects levels listed in the sediment quality guidelines of the Canadian Council of the Marine Environment to a sediment avoidance response. Since the amphipods did not biotransform contaminants, bioaccumulation was the only fate pursued to examine the bioavailability of PAH. For five Halifax Harbour sediments, a relationship was established between the threshold effects level representing the amphipods' avoidance response and the bioaccumulation of PAH. A body burden of 0.3-1.1 mumol/kg (wet weight) was determined for the sum of abundant parental PAH in amphipods exposed to sediments that initiated the behavioural effect. PAH were much more available from spiked sediments than from field sediments, with biota-sediment accumulation factors of 2.2-7.8 compared to <0.01-0.3, respectively. Animals exposed to PAH-spiked sediments avoided contaminated sediments when their body burden was up to seven times higher than observed with field sediments. This latter result and two exposures to sediments collected further away from sewage discharges point to a role for unidentified chemicals in the body burden and behaviour relationship. Further research is warranted to develop this promising assessment tool.