CS36 Ultraviolet Radiation
Date: Wednesday, June 12, 2002
Location: Poster Session - VCC
 
Vareschi E, Carl von Ossietzky Universität, Oldenburg, Germany, ekkehard.vareschi@uni-oldenburg.de
Wübben, D, , Carl von Ossietzky Universität, Oldenburg, Germany, dwuebben@hotmail.com
Zauke, G, P, Carl von Ossietzky Universität, Oldenburg, GERMANY, ger.peter.zauke@uni-oldenburg.de
 
WAVELENGTH AND INTENSITY SPECIFIC VERTICAL MIGRATION RESPONSE OF FRESHWATER ZOOPLANKTON TO UVB RADIATION
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UVB radiation is known to affect survival rate and reproduction of zooplankton. Therefore detailed information on UV mediated vertical movements is a key issue to asses the ecological significance of increasing natural UV radiation. The behavioral response (vertical movements) of five species of freshwater zooplankton (three Cladocera, two Copepoda) to UV radiation (280 to 400 nm) was investigated by exposing the animals to varying levels of UV-radiation in a sunshine-simulator and to varying wavelengths emitted by a monochromator. Vertical movements were registered using a Vertiquant, a device for automatically recording vertical migration of zooplankton. Cladocera showed a distinct downward movement of 2-10 cm in response to UV light. This response was mediated by UV radiation intensity (threshold intensity <10-7 W m-2) and wavelength (maximal response at 350-360 nm). In contrast, Copepods did not react to UV radiation, though LD50 experiments showed them to be as sensitive to UV radiation as Daphnia. These observations suggest that different zooplankton taxa will be differently affected by increasing UVB radiation, which might result in some shifts of species composition in certain environments.