UCR Hydrologist to Study Ecological Impact of Climate Change on Lakes
Five-year National Science Foundation grant and Funding from the National Park Service to support James Sickman’s study of nutrients in lakes in the high Sierra Nevada
RIVERSIDE, Calif. - What kind of threat does climate change pose to mountain lakes? How does climate change affect the rate of atmosphere deposition of nutrients to lakes - elements or compounds essential to the growth and survival of aquatic organisms? And how would increases in the concentration of such nutrients change the abundance of aquatic plant and animal species in lakes?
James O. Sickman, an assistant professor of hydrology at UC Riverside, will attempt to answer these questions, thanks to a five-year grant of $423,548 from the National Science Foundation’s program in Long Term Research in Environmental Biology, to be shared by UCR and UC Santa Barbara. An additional three-years of funding ($98,745) is being provide by the National Park Service. In particular, Sickman will measure the phosphorus and nitrogen content of atmospheric deposition and lake water in the Sequoia National Park in the Sierra Nevada, Calif., to determine how they are changing in response to climate change.
"We’re interested in understanding how a shift towards more rainfall and less snowfall, induced by climate change, is altering the ecology of Sierran lakes," said Sickman, a faculty member in the department of environmental sciences. "By the end of our project we hope to describe the linkages between lake ecology and both climate change and atmospheric deposition."
Atmospheric deposition of nutrients can enter lakes both as dry deposition, slowly descending nutrient-rich particulate matter, or in rainfall and snowfall. When lakes become enriched in dissolved nutrients, fertilization of algae and phytoplankton can result which can then alter the entire foodweb of the lake. Severe fertilization can deplete dissolved oxygen and endanger aquatic life.
"More productivity is not necessarily a good thing where Sierra Nevada lakes are concerned," Sickman said. "These lakes are chemically similar to distilled water and exist in granitic basins - this limits their ability to adapt to climate change and increasing nutrient deposition. We’re already seeing the chronic effects of excessive nutrients in lakes in Sequoia National Park. In some cases, phytoplankton growth has increased by a factor of three. We plan to determine whether the excess nutrients are being transported from the Central Valley or remote sources, such as China."
Excessive nitrogen and phosphorus can contribute to lake acidification, a reduction in dissolved oxygen, a loss of habitat, and changes in biodiversity. To get a longer perspective on the nutrient content of lakes in the high Sierra Nevada, Sickman also plans to analyze sediment cores from lakes in Sequoia and Yosemite National Parks in order to examine past atmospheric deposition. "Paleolimnology gives us a longer perspective and will help determine if conditions today differ significantly from those in the past. The major goal of the NPS-funded research is to develop critical loads for nutrient deposition that could be used by regulatory agencies to set air quality standards."
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