STP921

    Field and Laboratory Toxicity Tests with Shrimp, Mysids, and Sheepshead Minnows Exposed to Fenthion

    Published: Jan 1986


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    Abstract

    We conducted a series of laboratory pulse-exposure experiments to model short-term field exposures of two representative estuarine crustaceans, Penaeus duorarum and Mysidopsis bahia, to the organophosphate insecticide fenthion. These tests established acutely lethal and nonlethal concentrations during pulse exposures. The data were necessary for interpretation of responses of test animals in the field when fenthion concentrations changed rapidly with time.

    The toxicity of fenthion to caged pink shrimp, mysids, and sheepshead minnows (Cyprinodon variegatus) was determined in the field following two aerial applications separated by 72 h, to control adult saltmarsh mosquitoes. At one estuarine site, initial concentrations of fenthion in water were 1.5 µg/L following Spray 1 and 0.29 µg/L after Spray 2. Within 12 to 24 h, however, fenthion was not detectable (<0.01 µg/L) because of rapid tidal flushing and high dilution at this site. Although initial exposures approached or exceeded laboratory 24-h LC50s for pink shrimp (0.40 µg/L) and mysids (0.42 µg/L), no mortality occurred among caged animals. At a second site along a residential saltwater canal with limited tidal flushing and dilution, initial concentrations of fenthion were 2.6 µg/L (Spray 1) and 0.5 µg/L (Spray 2). Within 12 to 24 h post-spray, fenthion decreased to 0.4 µg/L (Spray 1) and 0.14 µg/L (Spray 2) and continued to diminish during the next 48 to 72 h. These concentrations approximated the 48- and 72-h LC50s for pink shrimp (0.22 µg/L and 0.15 µg/L) and mysids (0.37 µg/L and 0.18 µg/L). All exposure concentrations were three orders of magnitude below the 24-h LC50 for sheepshead minnows (1900 µg/L) and no mortality occurred among caged fish. By deploying caged pink shrimp and mysids daily, before and after each spray, in situ exposure regimes varied for each group and resulted in responses among caged test populations that ranged from no observed effect to 100% mortality.

    The responses of caged pink shrimp and mysids exposed to slowly changing concentrations of fenthion in the field were similar to what would have been predicted based on laboratory tests that established 24-, 48-, and 72-h LC50s. Laboratory pulse-exposure tests were predictive of no-effect and effect pulse exposures in the field. These comparisons demonstrated that predictions of fenthion toxicity based on laboratory test results were valid when field and laboratory exposure regimes were similar.

    Keywords:

    field validation, acute toxicity, fenthion, pulse exposures, shrimp, mysids, sheepshead minnows, aquatic toxicology


    Author Information:

    Clark, JR
    Research aquatic biologist, research aquatic biologist, research aquatic biologist, biological laboratory technician, research chemist, and research chemist, Environmental Research Laboratory, Gulf Breeze, FL

    Goodman, LR
    Research aquatic biologist, research aquatic biologist, research aquatic biologist, biological laboratory technician, research chemist, and research chemist, Environmental Research Laboratory, Gulf Breeze, FL

    Borthwick, PW
    Research aquatic biologist, research aquatic biologist, research aquatic biologist, biological laboratory technician, research chemist, and research chemist, Environmental Research Laboratory, Gulf Breeze, FL

    Patrick, JM
    Research aquatic biologist, research aquatic biologist, research aquatic biologist, biological laboratory technician, research chemist, and research chemist, Environmental Research Laboratory, Gulf Breeze, FL

    Moore, JC
    Research aquatic biologist, research aquatic biologist, research aquatic biologist, biological laboratory technician, research chemist, and research chemist, Environmental Research Laboratory, Gulf Breeze, FL

    Lores, ME
    Research aquatic biologist, research aquatic biologist, research aquatic biologist, biological laboratory technician, research chemist, and research chemist, Environmental Research Laboratory, Gulf Breeze, FL


    Paper ID: STP29023S

    Committee/Subcommittee: E47.08

    DOI: 10.1520/STP29023S


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