SS1.03 Zooplankton Response to Climate Variability
Date: Monday, June 10, 2002
Time: 2:15:00 PM
Location: Lecture Theatre
 
BoeingWJ, Louisiana State University, Baton Rouge, USA, wboeing@LSU.EDU
Williamson, C, E, Lehigh University, Bethlehem, USA, Cew0@lehigh.edu
Leech, D, M, Lehigh University, Bethlehem, USA, dmleech@duke.edu
 
SUNBURN OR RISK OF PREDATION - BALANCING CONFLICTING EVILS IN THE WATER COLUMN
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In nature organisms have to meet conflicting demands of food gathering, predator avoidance, and environmental constraints striving for maximal fitness. We conducted experiments revealing patterns of depth selection behavior by zooplankton in the presence and absence of the invertebrate predator Chaoborus punctipennis or its kairomone and UV-light. The zooplankton were enclosed in 2.2-m columns suspended in a lake. Some were transparent to UV-light while others were UV-shielding. The experiments were terminated by closing the six chambers of the columns using the built-in trap doors, and counting the zooplankton in each chamber separately. Chaoborus always migrated down regardless of the UV treatment. Chaoborus and UV had opposite effects on the distribution of the zooplankton. When Chaoborus was present, most zooplankton migrated to the water surface, while in the presence of UV the migration was downward. Simultaneous exposure to predators and UV-light resulted in clustering at intermediate depths. Chaoborus kairomone experiments did not show the same results but this might be due to the shorter incubation period.