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Washington and Lee University

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Liz George '12 studies environmental change in the Connecticut River

The goal of my thesis research is to use diatom species assemblages to reconstruct environmental change in the historic and geologic sedimentary record of the lower Connecticut River.

The study of diatoms as a proxy for environmental changes is useful both for gaining a better understanding of paleoclimate or riverine conditions and for improving predictions of future change. Diatoms have the potential to be very useful ecological monitors because they are the largest source of biomass and primary productivity on earth, can be found in all bodies of water, have a large variety of species, many of which are environmentally sensitive, and are well preserved in the geologic record due to their siliceous skeletons (Stoermer and Smol, 2010).

Because anthropogenic activity is likely to continue to increase in the area, it is important to understand how changes in water quality, such as nutrient content and salinity, affect the surrounding ecosystems. Studying diatoms in the sedimentary record will shed light on how these aspects of the river have changed in the past few millennia and give insight into potential future changes based both on human activity and natural geologic change (Stone, 2007).

In the summer of 2011, I worked with the Keck Geology Consortium to begin my thesis research. We took a 3-meter long core from South Cove, a shallow, tidal cove on the south end of the Connecticut River's confluence with Long Island Sound. After isolating the diatoms from 16 samples along the core, species were identified and compared in terms of preferred environments.

The findings of this study support the use of diatoms as a tool to improve the regional and global understanding of natural and human-induced changes in the aquatic environment. As environmental indicators, diatoms in this study revealed variability in temperature, salinity, phosphate, oxygen, and nitrate as well as species diversity and relative abundance of diatom genera and species over the past approximately 5700 years.

Stoermer, E. F. and Smol, J. P., 2010, The Diatoms: Applications for the environmental and earth sciences, 2nd ed. Cambridge, UK: Cambridge University Press.
Stone, J. R., 2007, Using diatoms as ecological and paleoecological indicators in riverine environments: Paleontological Society Papers, v. 13, p. 25-33.