IMIS

The watercolumn samples that were used to compile this dataset were collected in the framework of the MATURE project and were taken along a longitudinal transect in the estuaries of the Schelde (4 May 1993, 11 samples within a salinity range of 1 to 23 psu) and the Elbe (21 april 1993, 8 samples within a salinity range of 0.5 to 34 psu). At each sampling station, both unconcentrated (1L) and net samples (mesh size 10 mm) were collected. Diatoms were counted and identified. Details on the sampling and analyses procedures are described in the related publications. From the 11 stations that were sampled in the Scheldt estuary, there were 2 in the polyhaline zone, 4 in the mesohaline zone and 5 in the oligohaline zone. From the 8 stations in the Elbe estuary, there were 3 in the limnetic or freshwater tidal zone, 1 in the oligohaline zone, 1 in the mesohaline zone, 2 in the polyhaline zone and 1 in the euhaline zone. Additional information on the ecology of some Thalassiosira species was obtained from an existing dataset comprising 360 intertidal sediment samples (30 stations sampled monthly during one year) from the Schelde estuary. This dataset was compiled and used in the framework of the research that was conducted by Koenraad Muylaert, described in his Phd thesis: "Muylaert, K. (1999). Distribution and dynamics of protist communities in a freshwater tidal estuary. PhD Thesis. Universiteit Gent (RUG): Gent, Belgium. 192 pp." More specifically this dataset was used to study the diatom genus Thalassiosira (Bacillariophyta) in the estuaries of the Schelde and the Elbe. (chapter 1) The aim of this study was to give a detailed account of the observed Thalassiosira species, with remarks on their taxonomy, morphology and ecology. Their occurrence within the studied estuaries is compared to data from other estuaries worldwide.