The Importance of Water Level Changes and Shoreline Development in the Eutrophication of a Shallow, Seepage Lake

Water level fluctuations, whether climatically induced or the result of artificial regulation, can have a profound effect upon lake processes, especially in shallow lakes. Confounding the impact of changing water levels is nutrient input resulting from anthropogenic changes in land use. Paleolimnolo...

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Bibliographic Details
Published in:Proceedings of the Academy of Natural Sciences of Philadelphia 2010-11, Vol.160 (1), p.113-126
Main Authors: Garrison, Paul J, Laliberte, Gina D, Ewart, Brian P
Format: Article
Language:English
Subjects:
Bacillariophyceae
Diatoms
geochemistry
Lakes
Lakeshores
Lentic systems
Macrophytes
Paleolimnology
Phosphorus
Sediments
Shallow water
shoreland development
Shorelines
water level fluctuations
Watersheds
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Summary:Water level fluctuations, whether climatically induced or the result of artificial regulation, can have a profound effect upon lake processes, especially in shallow lakes. Confounding the impact of changing water levels is nutrient input resulting from anthropogenic changes in land use. Paleolimnological techniques were used in a shallow seepage lake to infer the importance of water level changes and shoreland development as a source of nutrients to the lake. A long-term record of lake level in a Wisconsin lake was obtained from the measurements obtained by residents, who measured the width of the beach in front of their property over 73 years. These measurements were converted to vertical elevation through a detailed survey in 2008. Additional lake elevations were inferred from a 110-year precipitation record. While the mean depth of the lake was 2.1 m, lake elevation fluctuated up to 2.4 m. Cottage development began in the 1920s, increased in the late 1930s and further increased in recent decades. The bulk sedimentation accumulation rate initially increased with early cottage development, but the rate tripled with intensified development in the latter part of the twentieth century. The increase in the sedimentation resulted from increased soil erosion. Even though erosional rates have declined in the last 2 decades, use of soil amendments, hydrated lime and synthetic fertilizers have resulted in additional nutrient input to the lake. Multivariate statistical techniques performed on the diatom community revealed the greater importance of phosphorus concentrations than changing lake elevation in structuring the diatom responses. This analysis suggested that shoreline development history was more important than changes in lake elevation as a source of nutrients to the lake. This shallow, seepage lake was much more responsive to landuse changes than to long-term water level fluctuations.
ISSN:0097-3157
1938-5293
DOI:10.1635/053.160.0112