title: Age-dependent survival, reproduction and photorepair activity in Daphnia magna (Straus, 1820) after exposure to artificial ultraviolet radiation.
abstract: We examined age-related vulnerability of Daphnia magna to UV-B (ultraviolet-B radiation, 280-320 nm), the age-related relationships between UV-B dosage and reproduction, and the effects of duration of PRR (photorecovery radiation) on survival and fecundity. Animals were exposed to 0, 6, 9 or 12 h UV-B (peak emission 312 nm) at 1, 2, 3 or 4 days of age and followed to 12 days. Survival decreased with increasing exposure to UV-B, but increased with age at exposure. Duration of UV-B, but not age at exposure, decreased offspring production. Survival increased with an increase in duration of PRR for animals of all ages; however, the effect was not age related. Three-day-old animals were exposed to 6 h of UV-B followed by 0-600 min of PRR. Survival was greatest in controls, lowest in the group that received no PRR and similar for all other groups. Most mortality occurred within the first 72 h postirradiation. Offspring production was highest in light controls, lowest in the UV-B-exposed group that received no PRR and not significantly different among other groups. This study demonstrates the need to consider age when examining the effects of UV-B on zooplankton and the need to monitor responses over a sufficient length of time.
authors.affiliation: Department of Biology, University of Winnipeg, 515 Portage Avenue, Winnipeg, Manitoba, Canada R3B 2E9. j.huebner@uwinnipeg.ca
authors.forename: Judith D
authors.initials: JD
authors.lastname: Huebner
authors.forename: Donna L W
authors.initials: DL
authors.lastname: Young
authors.forename: Nancy L
authors.initials: NL
authors.lastname: Loadman
authors.forename: Vanessa J
authors.initials: VJ
authors.lastname: Lentz
authors.forename: Murray D
authors.initials: MD
authors.lastname: Wiegand
mesh_terms: D000375:Aging / Q000528:radiation effects; D000818:Animals; D003621:Daphnia / Q000254:growth & development / Q000502:physiology* / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D012098:Reproduction / Q000528:radiation effects*; D014466:Ultraviolet Rays