Abstract
Anthropogenic chemicals in the environment during critical periods could potentially affect the physiology of the economically valuable American lobster ( Homarus americanus ). Endosulfan (Thiodan™ WP) is a broad-spectrum organochlorine insecticide widely used in agricultural areas in Canada that significantly affects survival and growth of lobster larvae based on acute exposure studies. To detect more subtle physiological effects of an acute (96-h) sub-lethal level (0.1 μg·L -1 ) of formulated endosulfan exposure on early juvenile lobsters, investigations of metabolic rates, growth and the tissue structure of the hepatopancreas were conducted on animals that molted following the exposure. The standard and active metabolic rates were not significantly affected, but their differential, defined as the metabolic scope (MS) was significantly decreased by 25% for exposed animals. Lobster growth and survival were not affected. For the exposed lobsters, minor alterations of the digestive cell structures were observed. These results suggest that the decrease in MS for exposed juvenile lobsters could have consequences in terms of survival in the wild by impairing their abilities to find a shelter, food or protect themselves from predators. The growth and survival in laboratory conditions suggests that lobsters may adjust their metabolism to pesticide exposure by maintaining a positive energy balance with some compensatory mechanisms; however, this may not be possible in their natural environment. This study suggests that conclusions based solely on lethal toxicity assays could be misleading for sublethal effects of contaminants on marine organisms, which could be investigated more thoroughly using an integrated approach based on physiological indicators.
Highlights
Coastal commercial fishing grounds in the southern Gulf of St
This study suggests that conclusions based solely on lethal toxicity assays could be misleading for sublethal effects of contaminants on marine organisms, which could be investigated more thoroughly using an integrated approach based on physiological indicators
This study provided the first values of metabolic rates and metabolic scope on American
Summary
Coastal commercial fishing grounds in the southern Gulf of St. Lawrence (sGSL), Canada, are subjected to high anthropogenic pressures, due to fishing activity and as a consequence of pollution inputs from industry, agriculture and aquaculture at nearby coastal sites, which were identified as an emerging issue (DFO, 2010). Increasing concerns about the toxic effects of pesticides on non-target aquatic organisms have emerged (Ernst et al, 2001). Increased interest in studies on toxicologic and metabolic effects of sublethal concentrations of specific contaminants including pesticides for lobsters began a decade ago after high mortalities in Long Island Sound (De Guise et al, 2005; Walker et al, 2005; Zulkosky et al, 2005). Lobster larvae and juvenile stages could be the most affected stages in a population exposed to contaminants
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