Using macroinvertebrates as indicators of lake health

Ben Timm ('14) and Gian Perani ('14) heading to work.

Ben Timm (’14) and Gian Perani (’14) heading to work.

By Tom Abare (’15) and Ben Timm ( ’14)

This summer as members of the Belgrade Lake’s Sustainability Project Research Team, we have been investigating the effects of best management practices (BMPs) for developed shoreline lots on the species diversity and abundance of macroinvertebrate communities of the Belgrade lakes. These organisms vary in their tolerance to habitat disturbance and pollution; therefore, making these communities useful as bio-indicators. This characteristic allows us to study the overall health of a lake, in part, by looking at which macroinvertebrates are present. Student research assistants during the summer of 2012 collected invertebrates from littoral habitats along transects at 0.5 and 1.0 m depths; macroinvertebrates were also collected using rock traps. These organisms were then sorted and classified to the level of order, we we did further analysis this summer.

Research student surveying transect in North Pond

Research student surveying transect in North Pond

Our task  has been to refine identification (mostly to the family level) and to calculate various metrics describing macroinvertebrate community composition.  Metrics calculated include the Family-based biotic index, the percent dominant taxa, and the Shannon Diversity Index. We have used these metrics to analyze the effects of BMPs by examining different developed sites and reference sites within a lake as well as across the three lakes being studied (North, East, and Great Ponds). We also are in the process of developing a multi-metric index through this analysis that will give us a comprehensive and effective tool for scoring and assessing lake health in the future.

Gian Perani ('14) and Ben Timm ('14) using aquascopes to get a better view of the lake bottom during a survey in North Pond.

Gian Perani (’14) and Ben Timm (’14) using aquascopes to get a better view of the lake bottom during a survey in North Pond.

To date, we have not yet found significant differences among many of the calculated metrics across different treatment types. Some metrics, however, do exhibit differences between the lakes. It appears that the effects of BMPs are not as easily visible on a site by site basis within one lake, but could be more readily noticed at a lake scale when comparing lakes with different trophic states. Our study of these organisms has been fascinating and allowed us to gain experience in field research and data analysis. We are excited about our potential results.

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