Leech, D. M. Lehigh University, dml2@lehigh.edu
Williamson, C. E. Lehigh University, cew0@lehigh.edu

 
UV RADIATION AND SEASONAL PATTERNS OF ZOOPLANKTON VERTICAL DISTRIBUTION: TESTING THE SOLAR BOTTLENECK HYPOTHESIS
 
High levels of UV radiation (UVR) in the surface waters of more transparent, low DOC lakes may result in a "solar bottleneck" for small, epilimnetic zooplankton. In essence, small zooplankton are trapped between remaining in the deeper lake strata where risk of damage from large zooplankton is high, and migrating into the surface waters where the risk of damage from UVR is high. This bottleneck is hypothesized to occur during the period surrounding summer solstice when solar radiation is greatest. A similar bottleneck would be absent in less UV-transparent lakes because shorter wavelength solar radiation is attenuated rapidly, thus creating a safe refuge for small zooplankton in the warm epilimnetic waters. We tested several predictions of the solar bottleneck hypothesis by combining analysis of a three year, multiple lake database with laboratory UV tolerance experiments with zooplankton. Both seasonal and vertical distribution and migration of zooplankton were examined in the database, and these distributional patterns were related to UV tolerance. The relationship between UV tolerance and persistence of high epilimnetic zooplankton population densities through summer solstice is strong in some species (Keratella taurocephala, Keratella crassa) but not in others (Diaptomus minutus, Keratella cochlearis).
 
Day: Wednesday, Feb. 3
Time: 12:00 - 12:15pm
Location: Sweeney Center
 
Code: CS65WE1200S