|Phytoplankton composition of stagnant and tidal ecosystems in relation to salinity, nutrients, light and turbulence|
Rijstenbil, J.W. (1987). Phytoplankton composition of stagnant and tidal ecosystems in relation to salinity, nutrients, light and turbulence. Neth. J. Sea Res. 21(2): 113-123
In: Netherlands Journal of Sea Research. Netherlands Institute for Sea Research (NIOZ): Groningen; Den Burg. ISSN 0077-7579, more
One of the main characteristics of the Delta area in the southwestern Netherlands is the wide variety of brackish water types. Phytoplankton developments were compared in a small mesohaline and polyhaline lake, and in a mesohaline and polyhaline part of an open estuary. Salinity differences affected phytoplankton distribution. This was most evident in diatoms of marine origin. In the mesohaline waters relatively euryhaline marine species of diatoms were found: Skeletonema costatum in all water types, and Actinocyclus ehrenbergii only in the estuary. Thalassiosira nordenskiøldii and Ditylum brightwellii showed some tolerance to a mesohaline environment. Detonula confervacea and the stenohaline Rhizosolenia delicatula were limited to the polyhaline waters. Both the relative abundance and the mean size of the diatoms increased with the degree of turbulence in the systems, which was low (except in early spring) in the lakes, but high in the tidal system. In spring, diatom blooms were a regular phenomenon in the mesohaline and polyhaline lakes. Ammonium was depleted during the diatom blooms in spring. Nitrate was depleted by flagellates, small diatoms, and green algae in the top of the photic zone of the lakes. As a result, nitrogen was limiting phytoplankton growth in summer and in autumn. At the estuarine locations large diatoms were found to be suspended in the completely mixed water column.