title: Repeated sublethal exposures to the sea lice pesticide Salmosan® (azamethiphos) on adult male lobsters (Homarus americanus) causes neuromuscular dysfunction, hypoxia, metabolic disturbances and mortality.
abstract: In Atlantic Canada and other salmon-growing regions, treatment of sea lice infestations in salmon aquaculture is necessary to protect fish health. The product Salmosan®, which contains the organophosphate azamethiphos as the active ingredient, is a pesticide presently used for treatment against sea lice. It is applied as a bath treatment and then released into the surrounding seawater. The potential for lethality to non-target species following acute and chronic exposures to Salmosan® has been studied over the past decade, however, the potential for sublethal effects on lobsters remains a concern. Adult male lobsters were exposed to 0.06, 0.5, and 5µgL-1azamethiphos for one hour, repeated five times, over 48h. Lobsters were assessed immediately after exposure and over six days of recovery. Inhibition of muscle cholinesterase activity was detected in lobsters exposed to 0.5 and 5µgL-1azamethiphos. The 5µgL-1dose was considered lethal (93% cumulative mortality). Significant changes in hemolymph plasma biochemistry were most apparent in the 5µgL-1exposure group in the immediate post-exposure samples. Citrate synthase activity was significantly lower in muscles of the 0.5µgL-1exposure group compared to control lobsters. Mean electron transport system and standard metabolic rates tended to be lower in muscle tissue of the 0.5µgL-1exposure group than control group lobsters. These results suggest that sublethal effects on lobster energetics may occur under laboratory exposure conditions (i.e., concentrations and duration) considered environmentally relevant, which could result in impairment under natural conditions.
authors: EcoNov Inc., 540 Gorge Rd., Moncton, NB, Canada E1G 3H8; Homarus Inc, Shediac, 408 Main St., Shediac, NB, Canada E4P 2G1. Electronic address: dounia@mfu-upm.com.
authors: Daoud
authors: D
authors: Dounia
authors: CrustiPath, PO Box 682, Charlottetown, Canada C1A 7L3. Electronic address: andrea@crustipath.com.
authors: Battison
authors: B
authors: Andrea
authors: Universite de Moncton, Department of Chemistry and biochemistry, 18 ave. Antonine-Maillet, Moncton, NB, Canada E1A 3E9. Electronic address: natalie.lefort@umoncton.ca.
authors: Natalie
authors: N
authors: Lefort
authors: Golder Associates Ltd., 300-2920 Virtual Way, Vancouver, BC, Canada V5M 0C4. Electronic address: Jordana_vanGeest@golder.com.
authors: Jordana Lynne
authors: JL
authors: Van Geest
keywords: Acetylcholinesterase; American lobster; Citrate synthase; Hemolymph biochemistry; Metabolic rate; Pesticide