Comparative impact of in situ UV exposure on productivity, growth and survival of Antarctic Phaeocystis and diatoms

Abstract: Depletion of stratospheric ozone over Antarctica enhances UV-B (280-320 nm) radiation reaching the Earth's surface during spring. UV-B in-fluences the growth and survival of marine phytoplankton. The near surface UV irradiance, in situ growth and primary production of the prymnesiophyte Phaeocystis c.f. pouchetii (HARIOT) LAGERHEIM and three diatoms were measured during UV exposure. Survival, growth and cell diameter were also determined after exposure. The flagellate stage in the life cycle of Phaeocystis was the only organism examined that suffered mortality as a result of natural UV exposure, however, UV-A (320-400 nm) was responsible for most of this mortality. Interspecific differences in production, cell concentration and growth were observed at sublethal irradiances. Such differences may lead to changes in phytoplankton species composition. 1