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Long-term changes in fish community structure in relation to the establishment of Asian carps in a large floodplain river

Solomon, L. E., R. M. Pendleton, J. H. Chick, and A. F. Casper. 2016.  Long-term changes in fish community structure in relation to the establishment of Asian carps in a large floodplain river.  Biological Invasions, On-Line First DOI 10.1007/s10530-016-1180-8

Abstract

The Upper Mississippi River System, including the Illinois River, has been invaded by a number of nonnative species including silver carp Hypophthalmichthys molitirx and bighead carp H. nobilis, collectively referred to here as Asian carps. Silver carp densities in the Illinois River have increased dramatically and now represent some of the highest densities of wild silver carp anywhere in the world. Asian carps have the potential to alter existing ecosystems by consuming planktonic resources and therefore, could have the ability to alter existing fish communities as most fishes are dependent on planktonic resources during early development. However, identifying the relationship of fish community structure to the establishment of Asian carps has yet to be thoroughly investigated. Using long-term fish community data collected by the Upper Mississippi River Restoration’s Long Term Resource Monitoring element, we investigate changes in fish community structure pre- and post-establishment of Asian carps. Significant differences in the pre- and post-establishment communities were observed for the majority of gears and habitats. Species contributing to changes between establishment periods included most sportfish species and catostomids, which were less abundant post-establishment of Asian carps, while shortnose gar, grass carp, and emerald shiner were more abundant. While our analyses show Asian carps are likely contributing to major differences in fish community structure, future research and long-term monitoring should investigate the mechanisms and interactions responsible for community changes as well as identifying any potential concurrent or confounding factors such as changes in river hydrology or sedimentation.

Keywords
Asian carps, Fish community structure, Upper Mississippi River System, Illinois River Long-term monitoring, Upper Mississippi River Restoration Long Term Resource Monitoring element