title: Assessing the risk to green sturgeon from application of imidacloprid to control burrowing shrimp in Willapa Bay, Washington-Part I: exposure characterization.
abstract: Willapa Bay and Grays Harbor (WA, USA) comprise the largest region of commercial oyster cultivation on the Pacific Coast. The activities of 2 species of burrowing shrimp impair growth and survival of oysters reared on the intertidal mudflats. To maintain viable harvests, the oyster growers have proposed controlling the shrimp by applying the insecticide imidacloprid onto harvested beds. Green sturgeon (listed in the Endangered Species Act) forage on burrowing shrimp and could be exposed to imidacloprid in the sediment porewater and through consumed prey. Studies were conducted to evaluate the likelihood that green sturgeon would be exposed to imidacloprid and to characterize the subsequent environmental exposure. Comparisons between treated and untreated control beds following test application of the insecticide suggested that green sturgeon fed opportunistically on imidacloprid-impaired shrimp. The highest interpolated imidacloprid residue concentrations in field samples following chemical application were 27.8 µg kg(-1) and 31.4 µg kg(-1) in porewater and shrimp, respectively. Results from modeled branchial and dietary uptake, based on conservative assumptions, indicated that the porewater exposure route had the greatest contribution to systemic absorption of imidacloprid. The highest average daily uptake from porewater (177.9 µg kg(-1) body wt) was 9.5-fold greater than total dietary uptake (18.8 µg kg(-1) body wt). Concentrations and durations of exposure would be lower than the levels expected to elicit direct acute or chronic toxic effects.
authors.affiliation: Washington Cooperative Fish and Wildlife Research Unit, School of Aquatic and Fishery Sciences, University of Washington, Seattle, Washington, USA.
authors.forename: John A
authors.initials: JA
authors.lastname: Frew
authors.affiliation: Department of Chemistry, University of Washington, Seattle, Washington, USA.
authors.forename: Martin
authors.initials: M
authors.lastname: Sadilek
authors.affiliation: Washington Cooperative Fish and Wildlife Research Unit, School of Aquatic and Fishery Sciences, University of Washington, US Geological Survey, Seattle, Washington, USA.
authors.forename: Christian E
authors.initials: CE
authors.lastname: Grue
mesh_terms: D000818:Animals; D061006:Bays; D002851:Chromatography, High Pressure Liquid; D003445:Crustacea / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D005399:Fishes / Q000378:metabolism; D019015:Geologic Sediments / Q000737:chemistry; D006207:Half-Life; D007093:Imidazoles / Q000032:analysis* / Q000633:toxicity; D007306:Insecticides / Q000032:analysis* / Q000633:toxicity; D013058:Mass Spectrometry; D000073943:Neonicotinoids; D009574:Nitro Compounds / Q000032:analysis* / Q000633:toxicity; D018570:Risk Assessment; D013997:Time Factors; D014861:Washington; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000633:toxicity
chemical_list: D007093:Imidazoles; D007306:Insecticides; D000073943:Neonicotinoids; D009574:Nitro Compounds; D014874:Water Pollutants, Chemical; C082359:imidacloprid
keywords: Burrowing shrimp; Exposure characterization; Green sturgeon; Imidacloprid; Willapa Bay