Fish community and food web responses to a whole-lake removal of coarse woody habitat

As lakeshores are developed, property owners often thin the riparian forest and remove older logs or fallen limbs from the adjacent littoral zone. This practice alters fish habitat and produces unknown ecosystem changes. To assess potential effects on fish communities and food web interactions, we removed more than 75% of the coarse woody habitat (CWH) from the treatment basin of Little Rock Lake, Wisconsin, while leaving the reference basin unaltered. Prior to CWH removal, the food webs in both basins were similar and dominated by aquatic prey. After CWH removal, largemouth bass (Micropterus salmoides) in the treatment basin consumed less fish, ate more terrestrial prey, and grew more slowly relative to the population in the reference basin. Yellow perch (Perca flavescens) in the treatment basin declined to extremely low densities as a consequence of predation and little or no recruitment. In contrast, perch in the reference basin were replenished by several successful cohorts produced in consecutive years. Maintenance of CWH appears to be crucial for sustaining desirable fishes and fisheries in lakes. Changes in CWH produce complex, long-lasting effects at the ecosystem scale.