CS36 Ultraviolet Radiation
Date: Wednesday, June 12, 2002
Location: Poster Session - VCC
 
PerkkiöT, Univ. Helsinki, Helsinki, Finland, tuomas.perkkio@helsinki.fi
Rautio, M, , Univ. Helsinki, Helsinki, Finland, milla.rautio@helsinki.fi
 
INTERACTION OF ULTRAVIOLET RADIATION AND ICE BREAK-UP TIMING ON THE SURVIVAL AND VERTICAL DISTRIBUTION OF A COPEPOD EUDIAPTOMUS GRACILOIDES
image
We tested experimentally the effect of natural UV radiation on the survival and diel vertical migration (DVM) of a calanoid copepod, Eudiaptomus graciloides, before, during and after the ice-break. The species originated from subarctic Fennoscandia where underwater UV intensity is influenced by ozone depletion, changes in DOC and timing of ice break-up. The Eudiaptomus from under the ice were most susceptible to UV radiation, later in summer the tolerance to UV increased substantially. Measured as mortality, all species were affected by both UVB and UVA radiation. Survival was highest and similar between species in the dark controls and photosynthetically active radiation (PAR) exposures. DVM was negligible under the ice and most pronounced during the ice-break. In natural environments species previous exposure to light and different protection strategies (pigmentation, vertical migration) are probably as important factors controlling the survival of zooplankton as radiation intensity and optical properties of water.