For the incised, sand-bed streams of north-central Mississippi, USA, fish predation is one plausible mechanism to explain both relatively low crayfish densities and differences in stream size occupied by various native crayfishes. I conducted two mesocosm experiments to test effects of a fish predator (channel catfish, Ictalurus punctatus) on the survival and size structure of native crayfishes (primarily Procambarus hayi and Orconectes chickasawae) in the presence and absence of shelter. I used predominantly the larger species, P. hayi, in the first experiment and the smaller species, O. chickasawae, in the second. Experiments lasted 19–21 d, and each consisted of four replicated treatments: crayfish without shelter, crayfish with shelter, crayfish and predator without shelter, crayfish and predator with shelter. In both experiments, catfish significantly reduced crayfish survival. Shelter significantly reduced catfish predation on the smaller, but not the larger, crayfish species. Comparisons between experiments showed that in tanks containing catfish, P. hayi had higher survival than O. chickasawae. In both experiments, the mean size of crayfish increased less in the presence than in the absence of catfish, and I argue that the effect is due largely to a reduction in crayfish growth. Channel catfish directly and indirectly influenced crayfish in experimental settings, with the degree of influence varying by crayfish species and presumably related to crayfish size. Thus, fish predation and shelter availability are likely important factors influencing densities of and macrohabitat use by these native crayfishes.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.
Vol. 158 • No. 1