Term of Award

Summer 1992

Degree Name

Master of Science in Biology

Document Type and Release Option

Thesis (restricted to Georgia Southern)


Department of Biology

Committee Chair

Michael P. Moulton

Committee Member 1

Stephen P. Vives

Committee Member 2

J. B. Claiborne


For many years it has been assumed that the alarm reaction in fishes to alarm substance, also called Schreckstoff, confers a predator avoidance advantage to those fishes which exhibit it. Although Hews (1988) demonstrated decreased predator effectiveness of aquatic insects on alarmed Bufo tadploes, no experiments have been done with fishes to show an advantage to the alarm reaction. Therefore, to test the possibility of an advantage to fishes which exhibit an alarm reaction, a predator choice study was developed where a largemouth bass, Micropterus salmoides, was given a choice between alarmed and nonalarmed fathead minnows, Pimephales promelas. Each trial took place in three adjoining aquaria with the bass located in the middle aquarium between two aquaria which contained minnows. After a control period of behavioral observation, the minnows in one aquarium were alarmed with an injection of conspecific extract into the aeration system while the minnows in the other aquarium were exposed to an injection of distilled water. During the pre- and post-injection periods, the time spent by the bass near each aquarium containing minnows and all predetermined predatory behaviors displayed by the bass were counted. No significant differences in the behavior of the bass were found during the pre-injection period. During the post-injection period a significant interaction between treatment and minute and between treatment and availability of cover indicates that the bass behaved differently towards alarmed and non-alarmed minnows. This implies an advantage for minnows exhibiting the alarm reaction.


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