Predation Rates and the Behavioral Response of Adult Brassy Minnows (Hybognathus hankinsoni) to Creek Chub and Smallmouth Bass Predators

• Published in: Copeia 1988-08, Vol.1988 (3), p.691-698
• Main Author: Schlosser, Isaac J.
• Format: Article
• Language: English
• Subjects: Agnatha and pisces; Animal ethology; Biological and medical sciences; Creeks; Fish; Freshwater; Fundamental and applied biological sciences. Psychology; Habitat selection; Hybognathus hankinsoni; Lotic systems; Minnows; Predation; Predators; Psychology. Psychoanalysis. Psychiatry; Stream habitats; Streams; Vertebrata; Wildlife habitats
• ISSN: 0045-8511; 1938-5110
• DOI: 10.2307/1445389

I assessed the influence of adult creek chub (Semotilus atromaculatus) and smallmouth bass (Micropterus dolomieui) predators on survival and habitat use of adult brassy minnow (Hybognathus hankinsoni) prey. Controlled experiments were conducted in an experimental stream to simultaneously assess: 1) the effectiveness of each predator at capturing minnow prey when riffle and raceway refugia exist; 2) the effect of the presence of each predator in pools on habitat use of prey; and 3) the influence of structural complexity of pool habitats on the interaction between predator and prey. Predation by creek chubs occurred but only at a very low level. Predation rates for smallmouth bass were 35-40 times higher than for creek chubs, when expressed as number of prey eaten per predator, and 6-7 times higher, when expressed as number of prey eaten per unit weight of predator. In the absence of predators, prey primarily selected structurally complex pools. Presence of the less effective creek chub predators caused a weak shift in prey distribution towards structurally simple pools. In contrast, presence of the more effective smallmouth bass predators caused a pronounced shift in prey distribution to shallow raceway and riffle refugia. These results are consistent with the hypothesis that habitat use and the magnitude of predator avoidance by prey fishes are directly related to the risk of predation posed by different predator taxa. Extrapolation of these experimental results to habitat use patterns in natural lotic ecosystems should, however, be restricted to small headwater streams (1st-2nd order) because of the very different scale of fish-habitat relationships in large river systems.