Does lake dredging affect biodiversity? Evaluating biodiversity levels of fish at various stages of the dredging process in freshwater lakes.

Abstract

Fish are important higher trophic level organisms whose presence in lakes can be used to help determine the health of an ecosystem. However freshwater fish populations have declined over the past few decades primarily due to exploitation and degradation of habitat. One process that is done in an attempt to restore freshwater lake habitat is dredging. However not much study has been done on the long term effects of lake dredging and we are unsure if the process is beneficial to freshwater fish in the long term. This study focuses on biodiversity levels in three freshwater lakes, one of which was undergoing the dredging process and one that had already undergone the dredging process, in northern Illinois and south central Wisconsin. Fish were collected through traditional angling methods and biodiversity was looked at through measures of Species Richness, Shannon Diversity Index rating, and the average size of Sunfish was also calculated for each lake and compared. Results show that lakes that have been dredged and undergone recovery has a statistically higher Shannon Diversity Index rating, and average sunfish size when compared to a lake that has never been dredged. The lake that has been dredged also has a higher species richness rating than the lake that has never been dredged. From the results of this study we can see that there is a significant difference in the biodiversity levels when comparing a lake that has never been dredged and a lake that has been dredged previously.