Monster Seminar Jam - Ultraviolet radiation in bluegill nests: timing is (almost) everything
Dr. Mark Olsen, Department of Biology, Franklin and Marshall College
Ultraviolet radiation (UVR: 280-400 nm) can be an important source of mortality for aquatic organisms, particularly in systems with low concentrations of dissolved organic carbon. Because fish are most vulnerable to UVR during the egg and larval stages, the timing and location of parental spawning can strongly influence mortality risk. Laboratory exposure assays and field experiments suggested that bluegill (Lepomis macrochirus), an ecologically important species in lakes across eastern and central North America, are potentially vulnerable to UVR-induced mortality as larvae. However, in situ estimates of UVR exposure in bluegill nests in a highly transparent lake indicated that most nests were exposed to relatively low levels of UVR. The predicted effect of UVR on bluegill survival was weak in part because many nests were located at depths by which much of the incident UVR had been attenuated or were shaded by overhanging trees. UVR exposure in bluegill nests also declined over the course of the spawning season due to seasonal changes in water transparency and median spawning depth. For many species, early spawning is thought to increase reproductive success. However, in some systems a consequence of early spawning may be an increased risk of UVR-induced mortality.
Date and Time:
April 10, 2008,
10:30 am - 1:00 pm
206-860-3380 send email