Investigations on phytoplankton have been carried out in Baltic coastal waters, which are widely separated from the sea. Corresponding to their distance to the sea they differ in their trophic level. Annual phytoplankton production and a mean biovolume of 100-200 g C . m-* and 2-10 1111113. 1-1 respectively were found for the mesotrophic level, of 200-400 g C . m-* and 10-20 mm" 1-1 for the eutrophic level, and of 400-600 g C . m-2 and over 20 1111113. 1-1 for the polytrophic level.In the course of nearly two decades of investigation a slight increase of phytoplankton biovolume, but no increase of primary production was recorded. Some changes in species composition are to be recognized in Greifswalder Bodden, if old literature is compared with recent data. In the Darss-Zingst boddens a shift from Cyanobacteria dominance towards Chlorophyceae dominance has appeared for at least 5 years. This was on account of the disappearance of Gomphosphaeria pusiffa, which is thought to be an indicator species of the mesotrophic level.

Sdtiiples of phytoplankton were taken from the Euphrat and Tigris Estuary (Shatt J-;\rab) i n .April 1974 and investigated by means of the inverted microscope. Among 228 species identified 111 the sainples 95 were of marine origin. The share of diatotns in tho total numbers of cells from d l stations aitiounted to 68flI,,. The abundance of planktonic, green algae amounted to 19",,. of the blue greens t o 13" The number of marine species continuously increased in thelongitudinal r i~~s of the 139 kni section considered. The data of the phytoplankton were compared with the gradation of soine environmental variables (temperature, transparency, dissolved oxjgeri, ( Iiloiide). Regular longitudinal or vertical differences of these parameters were not observed.Oscillatorin. agardhii GOM. 0. limoscr Aa.

No abstract

The measurement of ecosystem parameters normally involves considerable effort in tcrms of sampling and analysis due to their variation in time and space. This cont'ribution describes the advantages and properties of the integrated sample and demonstrates them by comparing the statistical properties of separate samples (number of Filinia longiseta per unit volume), and integrated sample (total chlorophyll a concentration) and phytoplankton samples analyzed by the Ctermohl method. A working hypothesis is presented to explain the causes of the overdispersion that hinders phytoplankton analysis and to suggest) ways of eliminating it.

The development of the phytoplankton was observed from 1984 t o 1986 in the Warnow-River (GDR, Mecklenburg). The dominant algae throughout the year were the Bacillariophyceae with their maximum in spring (1984: 36.1 mm3/1, 1986: 32.3 mrn"1) or in autumn (1985: 48.3 mmJ/I). There is not any liinitation of phytoplankton by inorganic nutritation (N, P) throughout the year. The phytoplankton production was most influenced by the turbulance of water. Classification of banked-up rivers with the help of the plankton-quotients of THUNMARK and NYCAARD is impossible.