Structure of the community of planktic algae of the white sea in relation to availability of oxidized or reduced forms of nitrogen and level of illumination
2011
Ilyash, L. V. | Zapara, E. V. | Belevich, T. A.
Phytoplankton sampled in Kandalaksha Bay of the White Sea in late June 2006 was exposed in situ for 14 days under two levels of illumination (E1 > E2) with the addition of 180 μM of nitrogen as nitrate, urea, ammonium, and glycine. Every 3 days, species composition, abundance, and biomass of algae were estimated. The maximum biomass (Bmax) of phytoplankton depended on nitrogen substrates and level of illumination. The differences in Bmax between phytoplankton assimilating different nitrogen substrates became more apparent under E2. Phytoplankton assimilating nitrates, urea, and ammonium had higher Bmax under E1, but algae grown with glycine had higher Bmax under E2. Although the values of Bmax differed, the structures of all assemblages were similar except for that grown on ammonium under E1. Competitive parameters of algae populations depended on the form of nitrogen and level of illumination in a species-specific manner. Comparison of the present data with results of similar experiments in 2005 revealed that structure of assemblages formed after nitrogen pulse additions depended not only on nitrogen forms and illumination level but also on initial (before pulse) structure of community and availability of nitrogen for algae.
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