title: Physiological effects of temperature and a herbicide mixture on the soft-shell clam Mya arenaria (Mollusca, Bivalvia).
abstract: The aim of the current study was to investigate effects of temperature and a mixture of herbicides on the physiological status of the bivalve Mya arenaria. Bivalves acclimated to two temperatures (7 and 18°C) were exposed for 28 d to 0.01 mg/L of a pesticide formulation containing dichlorophenoxyacetic acid (2,4-D), 2-(2-methyl-4-chlorophenoxy) propionic acid (mecoprop), and 3,6-dichloro-2-methoxybenzoic acid (dicamba). At days 7, 14, and 28, mortality, immune parameters (hemocyte number, phagocytic activity, and efficiency), biomarkers of oxidative stress (catalase [CAT] and superoxide dismutase [SOD] activities and malondialdehyde [MDA] content), the metabolic enzyme cytochrome C oxidase (CCO), a biomarker of pesticide exposure (acetylcholinesterase [AChE]), and the activity of an enzyme related to gametogenesis (aspartate transcarbamylase [ATCase]) were monitored in clam tissues. Gonadosomatic index (GSI), condition factor (CF), and sex were also assessed. In clams acclimated to 7°C, exposure to pesticide enhanced CCO activity and CF and decreased MDA content, hemocyte number, CAT, and SOD activities. In clams kept at 18°C, pesticide effects appeared minor compared with samples kept at 7°C. In bivalves acclimated to 18°C, CCO, SOD, and ATCase activity and MDA content were enhanced, and hemocyte number, CAT, and AchE activities and phagocytosis were suppressed. In samples exposed to pesticides, increased temperature enhanced MDA content and CCO and SOD activity and suppressed hemocyte number and CAT and AchE activity. A gradual sexual maturation was observed in both sexes through experimental time, but females had a higher sensitivity to temperature and pesticides compared to males. Increased temperature altered the ability of the sentinel species Mya arenaria to respond to pesticide exposures. Further work is needed to understand the impacts of increasing temperature on the whole St. Lawrence estuary ecosystem.
authors.affiliation: Università Cattolica del Sacro Cuore, Agricultural and Environmental Chemistry Institute, Piacenza, Italy. luna.greco@unicatt.it
authors.forename: Luna
authors.initials: L
authors.lastname: Greco
authors.forename: Jocelyne
authors.initials: J
authors.lastname: Pellerin
authors.forename: Ettore
authors.initials: E
authors.lastname: Capri
authors.forename: Florent
authors.initials: F
authors.lastname: Garnerot
authors.forename: Séverine
authors.initials: S
authors.lastname: Louis
authors.forename: Michel
authors.initials: M
authors.lastname: Fournier
authors.forename: Angela
authors.initials: A
authors.lastname: Sacchi
authors.forename: Marco
authors.initials: M
authors.lastname: Fusi
authors.forename: Dominique
authors.initials: D
authors.lastname: Lapointe
authors.forename: Patrice
authors.initials: P
authors.lastname: Couture
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000633:toxicity*; D008456:2-Methyl-4-chlorophenoxyacetic Acid / Q000031:analogs & derivatives* / Q000633:toxicity; D000110:Acetylcholinesterase / Q000378:metabolism; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002374:Catalase / Q000378:metabolism; D003996:Dicamba / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D003576:Electron Transport Complex IV / Q000378:metabolism; D005260:Female; D005618:Fresh Water / Q000737:chemistry; D008297:Male; D008315:Malondialdehyde / Q000378:metabolism; D049892:Mya / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D018384:Oxidative Stress; D012623:Seawater / Q000737:chemistry; D013482:Superoxide Dismutase / Q000378:metabolism; D013696:Temperature; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D015415:Biomarkers; D004338:Drug Combinations; D014874:Water Pollutants, Chemical; D015084:2,4-Dichlorophenoxyacetic Acid; D008315:Malondialdehyde; C008340:mecoprop; D008456:2-Methyl-4-chlorophenoxyacetic Acid; D002374:Catalase; D013482:Superoxide Dismutase; D003576:Electron Transport Complex IV; D000110:Acetylcholinesterase; D003996:Dicamba