Behavior of sunfish exposed to herbicides: A field study

Authors

  • Phillip W. Bettoli,

    Corresponding author
    1. Tennessee Cooperative Fishery Research Unit, Tennessee Technological University, Cookeville, Tennessee 38505
    • Tennessee Cooperative Fishery Research Unit,d̊ Tennessee Technological University, Cookeville, Tennessee 38505
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  • Patrick W. Clark

    1. Tennessee Cooperative Fishery Research Unit, Tennessee Technological University, Cookeville, Tennessee 38505
    Current affiliation:
    1. North Carolina Wildlife Resources Commission, 307 Travis Dr., Elizabeth, NC 27909
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  • The Unit is jointly sponsored by Tennessee Technological University, the Tennessee Wildlife Resources Agency, and the U.S. Fish and Wildlife Service.

Abstract

An underwater closed-circuit video system was used to remotely monitor and record the behavior of bluegills (Lepomis macrochirus) and redear sunfish (Lepomis microlophus) guarding their nests before, during, and after applications of aquatic herbicides. Nests were sprayed to achieve a nominal concentration of 4 mg/L of either a dipotassium salt of endothall (Aquathol-KD̊), a dimethylamine salt of 2,4-dichlorophenoxyacetic acid (2,4-D), or water (control). No significant differences in rates of nest abandonment existed among the three treatments (p > 0.10). Abandonment averaged 5.17 min for both species and herbicide treatments, whereas the herbicides persisted in the water column for at least 45 min. When abandonment occurred, congeners nearly always intruded on the nest to feed on eggs or fry. After spraying, the adjusted mean frequency of rim circling, fanning, and agonistic behaviors exhibited by bluegills guarding eggs did not differ among the three treatments (p ⩾ 0.35). These results suggest the two herbicides will not elicit pronounced shifts in reproductive behavior of sunfish when they are properly applied.

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