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Effects of pulp mill effluent on marine mussels in an on-site, flow-through bioassay

University of British Columbia

The potential effect of pulp mill effluent on the survival, growth, and condition index of marine mussels (Mytilus edulis) was investigated. Mussels were exposed to five environmentally relevant concentrations (0.23, 0.46, 1.01, 2.07, and 4.88% v/v) of pulp mill effluent diluted with ambient seawater, and a seawater control for 89 d. This study was conducted on-site at the Norske Canada pulp and paper mill in Campbell River, BC, to satisfy provincial biological monitoring requirements. Mussels were sorted into 1-mm size classes and distributed into individual cages, made of oyster netting. Whole wet weight and length were measured at experimental initiation and termination. At test initiation, 400 mussels were sacrificed; tissue and shell weights were measured to determine baseline conditions. Dissolved oxygen, temperature, pH, salinity, and effluent flow rates were monitored during the experiment. At test termination, tissue and shell weights were measured; and condition index, defined as the ratio of wet tissue weight to shell weight, was calculated. In addition, mussel tissue was analysed for resin acids, lipids, and moisture. Statistically significant reductions in survival were observed in the 0.46 to 4.88% v/v concentrations, as compared to the control, and an LC20 of 3.80% v/v, with 95% confidence intervals of 2.09 to >4.88% v/v, was calculated. No significant reductions in growth, based on changes in length and whole wet weight, and condition index were observed. Condition indices and tissue lipid concentrations of the mussels declined significantly over the exposure, as compared to the T = 0 group. In addition, the mussels exposed to 1.01 to 4.88% v/v effluent had significantly decreased lipid concentrations as compared to the control. Only dehydroabietic acid was detected in the mussel tissues and concentrations of <0.2 to 0.15 |ig/g (wet weight basis) were measured. This pulp mill effluent discharge may have an adverse effects on the long-term survival of mussels, if they are continually exposed to 0.5 % v/v effluent. It is not expected that reduced lipid content in native mussels in Discovery Passage would be observed, as effluent concentrations exceeding 1% unlikely to occur outside of a 250 m radius of the effluent discharge.

Text

2009-12-11

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http://hdl.handle.net/2429/16610

Resource Management and Environmental Studies

University of British Columbia

UBCV

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