Annual Report
December 2006
Project Title: Inferring Critical Nitrogen Deposition Loads to Alpine Lakes of Western National Parks and Diatom Fossil Records
PMIS number?
Funding agency: National Park Service
Contact information: Jasmine Saros, Dept. of Biology, University of Wisconsin-La Crosse, 1725 State Street, La Crosse, WI 54601, Tel: (608)785-8262, Fax: (608)785-6959, saros.jasm@uwlax
PROJECT ABSTRACT:
Shifts in algal (diatom) composition in alpine lakes are frequently the first indication of ecological perturbations in these systems. Of the major disturbances affecting alpine lakes, enhanced atmospheric nitrogen (N) deposition is one of the primary concerns. The critical N load that elicits ecological change in western alpine lakes is presently unclear. An understanding of this information would provide resource managers with a target value needed to improve aquatic ecosystem conditions. Changes in diatom community composition as a result of enhanced atmospheric nitrogen deposition have already been assessed in Rocky Mountain National Park as well as the Absaroka-Beartooth Wilderness Area. The critical N load which serves as a threshold to elicit these diatom shifts can be reconstructed by assessing the timing of diatom shifts across several sites in the western U.S. Sediment cores have already been collected from lakes in several national parks and adjacent wilderness areas. Using data collected by the National Atmospheric Deposition Program (NADP), we have identified three additional national parks located along a gradient of N deposition loads. Sedimentary diatom profiles from two lakes at or above treeline from North Cascades, Glacier and Sequoia National Parks will be determined and used to reconstruct the timing of shifts driven by enhanced N deposition.
PROGRESS TO DATE:
We are still in the process of obtaining suitable core material, as the most appropriate cores for this study were collected by Dixon Landers of the EPA. Dr. Landers collected these cores as part of another study, and thus had to ensure that he had an adequate amount of core material for that study before he could release any sediment. He recently confirmed that he will send us material from Pear Lake (Sequoia NP) as well as Oldman and Snyder Lakes (Glacier NP).
After several conversations with Dr. Mark Abbott, who has sediment cores from lakes in North Cascades NP, it is apparent that the lakes in this park are quite difficult to core due to the nature of the substrate. He only has long cores (spanning several thousands of years), which are either missing the recent sediments or are sectioned at a resolution that is too coarse for this study. There are suitable lakes for this study in the Pacific Northwest, but they all fall outside of national park boundaries.
Diatom counts on the cores from Dr. Landers will be performed during the spring and summer of 2007, and a critical N model will be developed from these data along with existing diatom profiles from Rocky Mountain NP.
BUDGET:
To date, none of the funds allocated to this project have been spent. I anticipate that the funds will be spent as indicated in the proposal budget.