|Abundance and composition of phytoplankton in relation to nutrient contents in the estuary of the Göta River, Sweden|
Björn-Rasmussen, S. (1976). Abundance and composition of phytoplankton in relation to nutrient contents in the estuary of the Göta River, Sweden, in: Persoone, G. et al. (Ed.) Proceedings of the 10th European Symposium on Marine Biology, Ostend, Belgium, Sept. 17-23, 1975: 2. Population dynamics of marine organisms in relation with nutrient cycling in shallow waters. pp. 43-60
In: Persoone, G.; Jaspers, E. (Ed.) (1976). Proceedings of the 10th European Symposium on Marine Biology, Ostend, Belgium, Sept. 17-23, 1975: 2. Population dynamics of marine organisms in relation with nutrient cycling in shallow waters. IZWO/Universa Press: Wetteren. ISBN 90-6281-002-0. 712 pp., more
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Investigations were carried out in the estuary of the Gota River from 1968 until 1974 with marked emphasis during the years 1971 and 1974. A sewage treatment plant which began to operate in 1972, changed the nutrient conditions for the phytoplankton. The present paper reports the results of the investigations carried out in 1971 and 1974. The environmental conditions were studied by analyses of salinity, temperature, transparency, oxygen-, chlorophyll- and nutrient content. The standing stock of phytoplankton was studied by the inverted microscope technique. After the sewage treatment plant came into operation the concentrations of nutrients decreased. The standing stock of phytoplankton remained, however, at approximately the same level. During the summer of 1974, phosphate-P was often completely consumed. The concentrations of nitrogen-nutrients were often so low that the growth rate could have been limited. During the same period the dominating species, Skeletonema costatum (Greville) Cleve became less abundant. The blooms observed were characterized by lower maximum cell densities and a greater number of species. No significant linear relationships among cell numbers, particulate-phosphorus and transparency were found. It is therefore concluded that a further reduction of the standing stock and the maximum cell concentrations as a result of the pre-precipitation of phosphate, will probably not automatically influence the transparency.