The Effects of Ultraviolet-B Radiation on Aquatic Invertebrates
Date of Graduation
Master of Science in Biology
There is strong evidence that decreases in stratospheric ozone have led to increased ultraviolet-B radiation at the surface of the Earth. However, surprisingly little is known about the effects of UV-B radiation on aquatic ecosystems. The purpose of this study was to assess the sensitivity of aquatic invertebrates to UV-B radiation. Solar simulators were used to expose five species of aquatic invertebrates to enhance levels of UV-B radiation. The simulators were calibrated to match local ambient solar radiation. UV-B measurements in a eutrophic pond revealed that 90% of the irradiance was extinguished at approximately 30 cm depth. The irradiance at the upper 5-20 centimeters was comparable to levels used in the simulators. Median lethal dose (LD₅₀) values were determined for the cladocerans Ceriodaphnia reticulata, Scapholeberis kingii, and Daphnia magna, the ostracod Cyprinotus incongruens, and the amphipod Hyalella azteca. Among the species, 96-h LD₅₀ estimates were quite variable, ranging from 4.2 to 84.0 μW/cm². These estimates indicated S. kingii to be highly sensitive, H. azteca, C. reticulata, and D. magna moderately sensitive, whereas the ostracod C. incongruens was very tolerant to UV radiation. A survey of the distribution of S. kingii in Missouri ponds indicated that lightly pigmented individuals were restricted to turbid habitats, a finding consistent with the observation that light morphs could be induced at low light levels in culture. The sensitivity of both morphs to UV-B radiation was surprisingly similar. Overall, this study suggests that, in shallow ponds without physical refuges, UV-B radiation would have the strongest effects upon cladocerans and amphipods occuring in the water column, whereas ostracods would be better protected.
© Robin D Hurtubise
Hurtubise, Robin D., "The Effects of Ultraviolet-B Radiation on Aquatic Invertebrates" (1996). MSU Graduate Theses. 89.