New Zealand Journal of Marine and Freshwater Research abstracts
Differential UVB-sensitivities
of five New Zealand freshwater zooplankton species
DIRK LUDWIG WÜBBEN
EKKEHARD VARESCHI
Institute for Chemistry and Biology
of the Marine Environment (ICBM)
University of Oldenburg
P. O. Box 2503
D-26111 Oldenburg, Germany
email: ekkehard.vareschi@uni-oldenburg.de
IAN HAWES
National Institute of Water & Atmospheric
Research Ltd
P. O. Box 8602
Christchurch, New Zealand
GREG BODEKER
National Institute of Water & Atmospheric
Research Ltd
P. O. Box 50 061, Omakau
Central Otago, New Zealand
Abstract The ultraviolet (UV) sensitivity of five species of
freshwater zooplankton (three Cladocera, two Copepoda) were investigated. The
animals were exposed to varying levels of UV-radiation in a sunshine-simulator
and the UV doses for 10 and 50% mortality (LD10, LD50) were estimated using a
dose-response model. To place these doses in context they were compared with
modelled clear-sky surface UV irradiances in New Zealand. The cladocerans
Daphnia carinata and Ceriodaphnia dubia were sensitive to levels
of UVB irradiance of LD10 = 18-25 kJ m-2 and LD50 = 35-37 kJ
m-2. These sensitivities are consistent with published values for
other cladocera. In contrast a third cladoceran, Bosmina meridionalis,
exhibited no higher mortality over the full range of the cumulative UVB-doses
used (3-40 kJ m-2) than controls receiving no UV exposure. The
copepod Boeckella delicata showed the highest UV-sensitivity of all
organisms tested (LD10 = 7 kJ m-2, LD50 = 33 kJ m-2)
whereas for Boeckella triarticulata, which was more heavily
pigmented than B. delicata, no UV-induced mortality was observed. Under
natural conditions UV irradiances of up to 100 kJ m-2
day-1 can fall on the surface of New Zealand lakes. Although this is
attenuated in natural waters, these data suggest that UVB irradiance may be a
significant ecological variable to some zooplankton species.
Keywords UVB radiation; zooplankton; New Zealand lakes
New Zealand Journal of Marine and Freshwater Research, 2001, Vol. 35:
635-645
0028-8330/01/3503-0635 $7.00 (c) The Royal Society of New Zealand
2001
PDF file of entire paper: medium quality (782K); (scanned from paper original: notes about this process)
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