Organochlorine contaminants in mummichog (Fundulus heteroclitus) living downstream from a bleachedkraft pulp mill in the Miramichi Estuary, New Brunswick, Canada

Abstract

AbstractMummichog, a small‐sized sentinel fish species, has been proposed for use in environmental effects monitoring programs conducted by pulp mills that release their effluent in marine waters. In order to evaluate the suitability of mummichog as a sentinel species and to support the interpretation of biological effects data, tissue concentrations of polychlorinated dibenzo‐p‐dioxins and dibenzofurans, (PCDD/Fs), chlorophenolic compounds (CPs), polychlorinated biphenyls (PCBs), and chlorinated pesticides were investigated in mummichog sampled in the Miramichi Estuary, which was receiving a bleached‐kraft mill (BKM) effluent, and in a reference estuary, the Bouctouche Estuary. Higher concentrations PCDD/Fs (up to 50 times), CPs (up to 60 times), DDT, and PCBs (up to 10 times) were found in mummichog sampled at the upstream site of the Miramichi Estuary. At this site, 2,3,7,8‐ tetrachlorodibenzo‐p‐dioxin toxic equivalent concentrations were slightly above the threshold for ethoxy resorufin O‐deethylase induction. Multivariate analyses on congener profiles revealed that the contamination by PCDD/Fs and CPs originated both from the BKM and from a former wood‐preservation plant and that PCDD/Fs and CPs typical of the BKM were transported 40 km downstream from the mill. Patterns and levels of persistent contaminants differed between sites within the Estuary, indicating that the fish did not mix during their growing period. These findings support the use of mummichog in environmental effects monitoring programs, because this species bioaccumulates chlorinated compounds contained in BKM effluent and is sedentary. The cause‐effect relationship between exposure to the BKM effluent and the observed biological responses will have to be demonstrated by laboratory studies because of the presence of multiple sources of contamination.