CS29 Phytoplankton & Primary Production
Date: Tuesday, June 11, 2002
Location: Poster Session - VCC
 
Doyle SA, University of Wisconsin-La Crosse, La Crosse, USA, mtnorang@hotmail.com
Saros, J, E, University of Wisconsin-La Crosse, La Crosse, USA, saros.jasm@uwlax.edu
Interlandi, S, J, Drexel University, Philadelphia, USA, inters@drexel.edu
 
PHYTOPLANKTON DISTRIBUTION IN ALPINE LAKES IN RELATION TO NURIENTS AND LIGHT
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We have observed recent, rapid changes in the algal community structure of alpine lakes in the central Rocky Mountains. The increase in atmospheric nitrogen (N) deposition in this area over the past century may be linked to these changes. To explore which factors play a role in structuring these algal communities, we determined the vertical distribution of phytoplankton in three lakes located in the Beartooth Mountains (Montana/Wyoming). These three lakes were situated along an elevational gradient, ranging from 2600 to 3300 m a.s.l., and varied in the severity of phosphorus (P) and/or N limitation of primary production. We found that Dinobryon sp. dominated communities in systems co-limited by N and P. When communities only experienced P-limitation, Dinobryon sp. coexisted with Fragilaria crotonensis, Asterionella formosa and Aulacoseira distans. Light was also an important control of phytoplankton distribution. As elevation increased, the chlorophyll maximum within the lake was found further down the water column and corresponded to the 1% attenuation depth for PAR. Dinobryon sp. did well under a range of light intensities while A. distans was only found in low light conditions.