Impact of UV-B radiation on uptake of15N-ammonia and15N-nitrate by phytoplankton of the Wadden Sea

✍ Scribed by G. Döhler

• Publisher: Springer-Verlag
• Year: 1992
• Tongue: English
• Weight: 494 KB
• Volume: 112
• Category: Article
• ISSN: 0025-3162
• DOI: 10.1007/bf00356294

✦ Synopsis

Natural marine phytoplankton populations from the German Wadden Sea and unialgal cultures of the haptophycean Phaeocystis pouchetii were tested in 1989 under controlled UV-B stress conditions. Assimilation of t 5N_nitrat e in phytoplankton consisting mainly of P. pouchetii, or in pure cultures of this alga, was found to be very sensitive to enhanced UV-B dosage in comparison t 5N-ammonia uptake. In contrast, in phytoplankton samples containing Ceratium spp., Coscinodiscus sp., Noctiluca sp. or others, rate of ~5NO3-uptake was higher and only slightly affected by UV-B irradiance compared to the P. pouchetii sample. UV-B inhibitory effect on uptake of inorganic nitrogen by P. pouchetii was more pronounced under strong white-light conditions and after a UV-B pre-illumination period of several hours than under low white light. Pools of glutamine and alanine decreased after UV-B exposure. Results are discussed with reference to the damaging effects of white light and UV-B on nitrogen metabolism.