Fish density and diversity changes in response to the removal of aquatic vegetation in Douglas Lake, Michigan.

Abstract

The rapid development of land is destructive to aquatic habitats. The removal of woody debris and the raking of littoral vegetation during development are harmful to organisms that use this organic matter for reproduction and defense. The purpose of this study is to see if vegetation removal impacts the number of fish present in a certain area and fish biodiversity in Douglas Lake, MI at the University of Michigan Biological Station. We placed 12 minnow traps across three areas that differed in vegetative cover (non-vegetated, vegetated, heavily vegetated), and we recorded the number of fish found in each trap. We used the Shannon Wiener Diversity Index to calculate fish biodiversity within each section and used a Kruskal Wallis test to determine if the amount of fish between each section was significantly different. The vegetated section held the highest fish biodiversity, as well as the highest species richness. The amount of fish collected was significantly different between each section (p-value=0.03807). There was no correlation between temperature and the amount of fish found. We concluded that fish prefer to occupy vegetated areas because they provide protection from predators and act as a refuge for fish of all ages and species.