The effects of organic pollution on the distribution of fucoid algae from the Istrian coast (vicinity of Rovinj)

Abstract

        Fucoid algae are rather susceptible to organic wastes and gradually disappear from polluted areas. During the last few years the impact by organic wastes increased drastically in the Istrian area, especially in the vicinity of the town of Rovinj. Marked changes in the general vegetation pat­tern were found. The distributional patterns of fucoids changed radically and reflect clearly the distribution of organic pollutants along the west coast of Istria. Individual species of fucoids exhibit different degrees of tolerance to environmental stresses. A scale was worked out reflecting the susceptibility of the previously dominant fucoids to organic pollution: Sargassum species, which disappeared from the area, are probably the most susceptible and Fucus virsoides which newly reappeared in some polluted si­tes, the least. The susceptibility of different Cystoseira spe­cies grades from C. spicata and C. crinita through C. adriatica to C. barbata and C. compressa which were found in tide pools of some polluted sites, first of all on nearshore islands.