Effects of solar UV radiation on photosynthetic performance of the diatom Skeletonema costatum grown under nitrate limited condition

Abstract

Availability of nutrients is known to influence marine primary production; and it is of general interest to see how nutrient limitation mediates phytoplankton responses to solar ultraviolet radiation (UVR, 280-400 nm). The red tide diatom Skeletonema costatum was cultured under nitrate (N)-limited and N-replete conditions and exposed to different solar irradiation treatments with or without UV-A (315-400 nm) and UV-B (280-315 nm) radiation. Its photochemical quantum yield decreased by 13.6% in N-limited cells as compared to that in N-replete ones under photosynthetically active radiation (PAR)-alone treatment, and the presence of UV-A or UV-B decreased the yield further by 2.8 and 3.1%, respectively. The non-photochemical quenching (NPQ), when the cells were exposed to stressful light condition, was higher in N-limited than in N-replete grown cells by 180% under PAR alone, by 204% under PAR + UV-A and by 76% under PAR + UV-A + UV-B treatments. Our results indicate that the N limitation exacerbates the UVR effects on the S. costatum photosynthetic performance and stimulate its NPQ.

Interactive effects of nitrogen and light on growth rates and RUBISCO content of small and large centric diatoms

“…Low N often limits phytoplankton growth (Mei et al 2011; Moore et al 2013; Li and Gao 2014) as indeed found here for T. pseudonana (Fig. 1a).…”

Interactive effects of and light on growth rates and RUBISCO content of small and large centric diatoms

“…Nitrogen is a major material to build up cells; therefore, a low media N level is usually believed to limit phytoplankton growth (Li and Gao, 2014;Mei et al, 2011;Moore et al, 2013) as found here for T. pseudonana (Fig. 1a).…”