SS1.03 Zooplankton Response to Climate Variability
Date: Monday, June 10, 2002
Time: 2:00:00 PM
Location: Lecture Theatre
 
LeechDM, Lehigh University, Bethlehem, USA, dmleech@duke.edu
Boeing, W, J, Louisiana State University, Baton Rouge, USA, wboeing@lsu.edu
Williamson, C, E, Lehigh University, Bethlehem, USA, cew0@lehigh.edu
 
SEPARATING THE EFFECTS OF UV AND FISH ON ZOOPLANKTON VERTICAL MIGRATION
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While predation is widely recognized as an important factor influencing zooplankton vertical migrations, less attention has been given to UV radiation. In high UV systems, it is likely that both factors interact to influence zooplankton distribution patterns. We examined the vertical movements of zooplankton in the presence and absence of juvenile fish or fish kairomone and UV radiation. Organisms were placed in 2.2 m columns that either transmitted or blocked UV. Columns were then suspended at the surface of a high UV lake. Fish juveniles generally migrated downward regardless of the UV treatment. Consequently, fish and UV often had the opposite effect on zooplankton migrations. Most zooplankton migrated upward in the presence of fish but migrated downward in the presence of UV. Exposure to both UV and fish resulted in zooplankton aggregating at intermediate depths in the columns. In the presence of juvenile fish kairomone, most zooplankton, except Daphnia, migrated downward regardless of UV treatment. These observed patterns suggest that both predation and UV influence the vertical distribution of zooplankton in high UV lakes.