EN
The vegetation along the Polish coast was subjected to qualitative analysis. 38 plant taxa were identified: 24 Chlorophyta, 3 Pheophyta, 9 Rhodophyta and 5 Spermatophyta. The seasonal variation in the occurrence of macrophytobenthos in the Gulf of Gdansk was studied. Green algae were most abundant in the summer (May-September), red algae in the autumn (August-November). A significant expansion of Ectocarpaceae species was found to have oc-curred. Ectocarpus siliculosus and Pilayella litoralis, especially the later, are species which have expanded along the whole Polish coast. Enteromorpha species, mainly E. compressa and E. intestinalis, and also Cladophora species, especially C. albida, C. sericea and C. vaga-bunda were common. The changes observed in the vegetation during the last few years show that the increase in trophy is significant because the species diversity has shifted to the domi-nance of one or a few species occurring at very high densities