Williamson, C. E. Lehigh University, cew0@lehigh.edu
Olson, O. G. Lehigh University, olsono@uregina.ca
Lott, S. E. Lehigh University, sel2@lehigh.edu
Walker, N. D. Lehigh University, ndw2@lehigh.edu
Engstrom, D. R. Science Museum of Minnesota, dre@maroon.tc.umn.edu

 
UV RADIATION AND ZOOPLANKTON COMMUNITY STRUCTURE ALONG A DEGLACIATION CHRONOSEQUENCE OF LAKES IN GLACIER BAY ALASKA.
 
We investigated changes in UV attenuation and zooplankton community structure in a set of lakes along a deglaciation chronosequence in Glacier Bay Alaska. Terrestrial succession in the watersheds of these lakes results in increasing dissolved organic carbon (DOC) content over time. Due to the primary role of DOC in controlling UV attenuation in lakes, one would suspect a gradient in UV attenuation and possibly plankton community structure in lakes of different ages. UV attenuation depths (1% of surface irradiance at 320 nm) ranged from 0.6 m in the oldest lake in the set (90 years old), to greater than 17 m in the youngest lake (10 years old). Zooplankton community structure also changed across lakes of different ages. The major difference among lakes was the absence of two primarily epilimnetic species (Asplanchna and Ceriodaphnia) in all but the oldest lake, and the absence of Bosmina, which was abundant throughout the water column, in the four youngest lakes. Transplant experiments in which UV radiation was manipulated in situ revealed that all three of these species perish when exposed to UV levels found in the surface waters (0.5 m depth) of the youngest lake.
 
Day: Wednesday, Feb. 3
Time: 11:45 - 12:00pm
Location: Sweeney Center
 
Code: CS65WE1145S