Distribution of phytobenthos biomass in the Gulf of Riga (1984–1991)

Abstract

Floristic studies of phytobenthos in the Gulf of Riga have been carried out since the 18th century. The first quantitative data, however, are from the mid 1960’s. The present paper describes distribution of phytobenthos biomass in the Gulf of Riga as could be constructed from several investigations in the late l980’s.Material from more than 260 locations was used, which was published only partly. The littoral zone of the Gulf of Riga provides a suitable habitat for a great number of different benthic communities. Forty three species of macroalgae were identified.The distribution of the different species as well as the total biomass of the communities has a strong regional pattern which relates to existing differences in ecological conditions. The material was classified according to species composition by Weighted Centroid clustering method using Simple Matching Coefficient as similarity measure. Three different groups of communities were identified and described in terms of structure and environmental factors controlling the distribution of phytobenthic communities in the area.