16-22 Comparing Pristine and Human-Impacted Lakes: Geochemistry, Ostracodes, and Microplastics in Northeastern Connecticut

Session: From Thin Section to Outcrop: Exploration of Undergraduate Research (Posters)

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Abstract:

Lakes in New England experience a range of human influences at varying degrees. Comparing the fauna found within pristine lakes with little human influence on non-pristine lakes with high human influence can give us a sense of how humans are impacting vital lake systems.

We examined four lakes in northeastern Connecticut: two located on the campus of the University of Connecticut and two in nearby (within 6 km) protected or residential areas. The two lakes on campus, Mirror Lake and Swan Lake, are both human-made, approximately the same size, and have a high amount of human activity. The two off-campus lakes, Tift Pond, a kettle lake, and Echo Lake, a dammed reservoir, are part of the Joshua’s Trust nature reserve and are similar in size to Mirror and Swan Lake. Sediment and water samples were collected in fall 2025, and in situ geochemical measurements of pH, and conductivity were taken in November using an Orion Star A329. Sediment was dried, powdered, and analyzed via a handheld XRF unit using standard methods. Elemental concentration was analyzed and compared using non-metric multidimensional scaling analysis through PAST v. 5.0. Additionally, ostracodes were picked from sediment samples using a binocular microscope and imaged using a Leica M205c microscope with LASX software. Microplastic material was picked from sediment samples after sieving 250-micron mesh screens.

Geochemical measurements show that Tift Pond and Echo Lake are more similar compared to Mirror Lake and Swan Lake. Non-metric multi-dimensional scaling analysis of the XRF elemental values: Al, Si, P, S, K, Ca, Mn, Fe indicate geochemical differences between the lakes. Echo Lake is more geochemically distinct than Mirror Lake, Swan Lake, and Tift Pond. Ostracodes were recovered from all lakes except for Echo Lake. Darwinula stevensoni was recovered only from Tift Pond, while Cypridopsis vidua was found in Tift Pond, Mirror Lake, and Swan Lake. Microplastics were more abundant in Swan Lake and Echo Lake than in Mirror Lake and Tift Pond.

Comparing these lakes demonstrates that human activity impacts sediment geochemistry, creating less favorable conditions for sustaining the lake’s fauna.

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