Effect of UVB radiation on the survival, feeding, and egg production of the brackish-water copepod, Sinocalanus tenellus, with notes on photoreactivation

Abstract

We examined the effects of UVB radiation on hatching success of eggs, survival of various naupliar and copepodite stages, and feeding and egg production of adult females of the brackish-water copepod, Sinocalanus tenellus, by exposure to varying doses of UVB irradiance in the laboratory. Artificial UVB radiation resulted in an increased mortality of eggs, nauplii and copepodites with increasing UVB doses. UVB induced damage was stage-specific with eggs being most susceptible (LD50= 4.1 kJ m−2 ) and adult females being least susceptible (LD50= 16.7 kJ m−2). Effects on feeding and egg production of adult females were significantly evident at UVB doses higher than 11.0 kJ m−2 and 7.0 kJ m−2, respectively. We also examined the photorepair response of eggs and various developmental stages in simultaneous irradiation of UVB and enhanced PAR. With enhanced PAR there was a considerable recovery against UVB damage, being higher for younger animals than older ones. In nature, however, solar UVB radiation may rarely cause appreciable damage to S. tenellus population due to optically high attenuation properties of their habitat waters.