Toxicity testing of sediment collected in the vicinity of effluent discharges from seafood processing plants in the maritimes.

There are over 1100 fish-processing plants in Canada and the majority of them discharge untreated effluents directly to marine or estuarine receiving environments. The purpose of this study was to evaluate chemical and toxicological characteristics of sediments near fish-processing plant effluent discharges to assess potential impacts of seafood-processing effluents on receiving environments. Eighteen sediment samples were collected near effluent discharges of six seafood-processing plant outfalls in New Brunswick, Canada in the winter of 2006. Ammonia levels ranged from <0.2 to 3480 microg/g, sulfide levels ranged from <0.4 to 6970 microg/g, and redox ranged from -255 to 443 mV. Only one sample had a Microtox Solid-Phase Test IC(50) value below 1000 mg/kg, whereas three samples caused greater than 30% reduction to amphipod survival. Redox, sulfide, and ammonia concentrations were all found to be significantly related to both Eohaustorius estuarius survival and Microto (Vibrio fischeri) IC(50). An increase in sulfide (R (2) = 0.584; 0.750) and ammonia (R (2) = 0.478; 0.552) and a decrease in redox (R (2) = 0.485; 0.651) were associated with an increase in toxicity to E. estuarius and Microtox, respectively. The highest toxicity to both test organisms, and the most contaminated sediments based on physical/chemical characteristics measured, was observed in samples from Blacks Harbour.