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Sublethal Exposure to UV Radiation Affects Respiration Rates of the Freshwater Cladoceran Daphnia cafawba
Author(s) -
Fischer Janet M.,
Fields Peter A.,
Pryzbylkowski Peter G.,
Nicolai Jaclyn L.,
Neale Patrick J.
Publication year - 2006
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1562/2005-08-30-ra-664
Subject(s) - respiration , respiration rate , cladocera , daphnia , biology , zoology , toxicology , ecology , botany , crustacean
We examined the effects of UV radiation (UVR) on metabolic rates of the freshwater cladoceran Daphnia catawba . We exposed D. catawba to UVB for 12 h in a lamp phototron at levels of 2.08 and 4.16 kJ m ‐2 both with and without concomitant exposure to UVA and visible photorepair radiation (PRR). We also included a group that received PRR only and a dark control group. Respiration rates were measured for 6 h following exposure. Respiration rates increased by 31.8% relative to the dark control at the lowest level of UVB stress (2.08 kJ m ‐2 UVB with PRR), whereas respiration was inhibited by 70.3% at the highest stress level (4.16 kJ m ‐2 UVB without PRR). Survival rates in the group that received PRR only and the group exposed to 2.08 kJ m ‐2 and PRR were not significantly different from that in the control group; however, the survival rate was reduced for all other UVR exposures. We hypothesize that enhanced respiration rates reflect energetic costs related to repair of cellular components damaged by sublethal levels of UVR. Increases in respiration rate of the magnitude we found in our experiment could significantly reduce energetic reserves available for growth and reproduction, especially in cases where these costs are incurred repeatedly during a series of days with high levels of UVR.