Although the common carp (Cyprinus carpio), an invasive benthic fish from Eurasia, has long been strongly implicated in the disappearance of vegetative cover and reduced waterfowl abundance in North American shallow lakes, the details of this relationship are obscure. This study documented ecological changes in a recently restored shallow lake (Hennepin and Hopper Lakes, IL, USA) at a time that it was experiencing a large increase in its carp population. We estimated the abundance and biomass of carp 7 years after this lake had been restored and then back-calculated carp population size across time while examining changes in the lake's plant and waterfowl communities. We found that the biomass of carp remained below ~30 kg/ha for 5 years following restoration, but then increased to ~100 kg/ha in the sixth year following a strong recruitment event. Although a carp biomass of <30 kg/ha had no discernible effects on vegetative cover (which exceeded 90%) or waterfowl (which exceeded 150,000 individuals during fall censuses), the increase to 100 kg/ha was associated with a ~50% decrease in both vegetative cover and waterfowl. A further increase in carp biomass to over 250 kg/ha during the seventh year coincided with a decrease in the vegetative cover to 17% of the lake's surface and a decline in waterfowl use to ~10% of its original value. These data suggest that the common carp is extremely damaging to the ecological integrity of shallow lakes when its density exceeds ~100 kg/ha. Since the biomass of carp in Midwestern shallow lakes commonly exceeds this value by 3-4 times, it seems likely that carp are responsible for the large-scale habitat deterioration described in many of these ecosystems.
Bibliographical noteFunding Information:
Acknowledgments This research was funded by the Wetlands Initiative (Chicago, IL). Ken Seemann and Jeff Riedemann conducted the carp seining. Mario Travaline, Keith Philippe, and Brett Miller helped with otolith preparation and reading. Joshua Stafford and Aaron Yetter from the Illinois National History Survey, Steven Forbes Biological Station provided the waterfowl data. Wayne Herndon from the Illinois Department of Natural Resources collected the fish community data. Dr. Donald Hey, Rick Seibert, and numerous volunteers from The Wetlands Initiative helped with carp sampling. Jake Osborne helped with final edits. Haude Levesque helped with Fig. 1. Comments provided by two anonymous reviewers substantially improved this article.
Copyright 2009 Elsevier B.V., All rights reserved.
- Biological invasion
- Cyprinus carpio