title: Effects of a pesticide and a parasite on neurological, endocrine, and behavioral responses of an estuarine fish.
abstract: In coastal waters, pesticides and parasites are widespread stressors that may separately and interactively affect the physiology, behavior, and survival of resident organisms. We investigated the effects of the organophosphate pesticide chlorpyrifos and the trematode parasite Euhaplorchis californiensis on three important traits of California killifish (Fundulus parvipinnis): neurotransmitter activity, release of the stress hormone cortisol, and behavior. Killifish were collected from a population without E. californiensis, and then half of the fish were experimentally infected. Following a 30 day period for parasite maturation, infected and uninfected groups were exposed to four concentrations of chlorpyrifos (solvent control, 1-3ppb) prior to behavior trials to quantify activity, feeding behavior, and anti-predator responses. Water-borne cortisol release rates were measured non-invasively from each fish prior to infection, one-month post-infection, and following pesticide exposure. Killifish exposed to 3ppb chlorpyrifos exhibited a 74.6±6.8% and 60.5±8.3% reduction in brain and muscle acetylcholinesterase (AChE) activity relative to controls. The rate of cortisol release was suppressed by each chlorpyrifos level relative to controls. Killifish exposed to the medium (2ppb) and high (3ppb) pesticide concentrations exhibited reduced activity and a decrease in mean swimming speed following a simulated predator attack. Muscle AChE was positively related to swimming activity while brain AChE was positively related to foraging behavior. ​No effects of the parasite were observed, possibly because of low metacercariae densities achieved through controlled infections. We found that sublethal pesticide exposure has the potential to modify several organismal endpoints with consequences for reduced fitness, including neurological, endocrine, and behavioral responses in an ecologically abundant fish.
authors.affiliation: San Diego State University, Department of Biology and Coastal and Marine Institute, 5500 Campanile Drive, San Diego, CA 92182, United States; University of California Davis, Department of Environmental Science and Policy, One Shields Avenue, Davis, CA 95616, United States. Electronic address: violetrenick@gmail.com.
authors.forename: Violet Compton
authors.initials: VC
authors.lastname: Renick
authors.affiliation: University of California Davis, Department of Environmental Science and Policy, One Shields Avenue, Davis, CA 95616, United States; Rice University, BioSciences, 6100 Main Street, Houston, TX 77005, United States.
authors.forename: Kelly
authors.initials: K
authors.lastname: Weinersmith
authors.affiliation: Southern California Coastal Water Research Project, 3535 Harbor Blvd. Suite 110, Costa Mesa, CA 92626-1437, United States.
authors.forename: Doris E
authors.initials: DE
authors.lastname: Vidal-Dorsch
authors.affiliation: San Diego State University, Department of Biology and Coastal and Marine Institute, 5500 Campanile Drive, San Diego, CA 92182, United States.
authors.forename: Todd W
authors.initials: TW
authors.lastname: Anderson
mesh_terms: D000110:Acetylcholinesterase / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D001921:Brain / Q000187:drug effects / Q000201:enzymology; D004390:Chlorpyrifos / Q000633:toxicity; D023781:Fundulidae / Q000378:metabolism* / Q000469:parasitology; D005880:Gills / Q000187:drug effects / Q000378:metabolism; D006854:Hydrocortisone / Q000378:metabolism; D018482:Muscle, Skeletal / Q000187:drug effects / Q000201:enzymology; D010575:Pesticides / Q000633:toxicity*; D013550:Swimming; D014200:Trematoda / Q000502:physiology*; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D010575:Pesticides; D014874:Water Pollutants, Chemical; D000110:Acetylcholinesterase; D004390:Chlorpyrifos; D006854:Hydrocortisone
keywords: Behavior; Chlorpyrifos; Euhaplorchis californiensis; Fundulus parvipinnis; Multiple stressors; Parasites