Development of a Fish-Based Index of Biotic Integrity for Lakes in Eastern South Dakota

Index of Biotic Integrity (IBI) was developed as a means to assess the biological impact of water quality issues in U.S. waters.  Most IBIs used today are fish-based and have been developed for lotic systems but few have been developed for lentic systems.  In South Dakota, 15% of lakes do not presently meet beneficial uses, and this number may increase due to more recent land conversion activity within watersheds on the eastern side of the state. The goal of this study is to develop a fish-based lake IBI for eastern South Dakota lakes using extant annual standardized gill and trap nets data collected by the South Dakota Department of Game, Fish and Parks from 58 lakes. Fish were categorized into metric classes reflecting their tolerance to disturbance. A suite of 63 potential metrics were evaluated for how each responded to various degrees of human disturbance occurring within watersheds. Preliminary analysis indicated that six metrics (e.g., abundance of native Centrarchidae, percent insectivores, percent moderately tolerant species, percent top carnivores, and richness of Cyrpinidae) best described levels of disturbance between lakes. Future analysis will examine/confirm the use of these metrics for the rapid bioassessment of ecosystem persistence.