Direct and Indirect Effects of Fish Predation on the Replacement of a Native Crayfish by an Invading Congener
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Date
1993
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Abstract
In Ohio streams, the crayfish Orconectes rusticus is replacing O. sanborni, and herein we test how predators
influence this replacement. In a field survey, crayfish were scarce when fish were abundant, suggesting that predators can adversely affect these prey. In laboratory experiments, we examined underlying mechanisms for this inverse relationship; specifically, we tested how crayfish species, adult aggression, and habitat heterogeneity influenced the predator-prey interaction. In a laboratory stream, smallmouth bass (Micropterus dolomieu) ate
similar numbers of equal-sized O. rusticus and O. sanborni, but when sizes mimicked those in the field (i.e., O. rusticus 4 mm > O. sanborni), fewer O. rusticus were eaten. Fish also reduced juvenileactivity and behaviors whereas adult aggression increased the frequency of these risky responses. More affected by adult crayfish, O. sanborni should suffer disproportional predation where adults and juveniles interact. Thus, fish predators should increase replacement rates and adult aggression should further accelerate this process. Manifested through
crayfish size, both indirect and direct predator effects contribute to the replacement of O. sanborni by O. rusticus
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Keywords
crayfish, fish predation, replacement rates
Citation
Mather, Martha E.; Stein, Roy A. "Direct and Indirect Effects of Fish Predation on the Replacement of a Native Crayfish by an Invading Congener," Canadian Journal of Fisheries and Aquatic Sciences, v. 50, no. 6, 1993, pp. 1279-1288.