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

Abstract

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 μg/g, sulphide levels ranged from <0.4 to 6970 μg/g and redox ranged from -255 to 443 mV. Only one sample had a Microtox™ Solid-Phase Test IC50 value below 1000 mg/kg while three samples caused greater than 30 % reduction to amphipod survival. Redox, sulphide and ammonia concentrations were all found to be significantly related to both Eohaustorius estuarius survival and Microtox™ (Vibrio fischeri) IC50. An increase in sulphide (R2=0.584; 0.750) and ammonia (R2=0.478; 0.552) and a decrease in redox (R2=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.