SEASONAL-CHANGES IN THE ABUNDANCE OF INTERTIDAL ALGAE IN SOUTHWESTERN ICELAND

Algal cover was measured for three years at approximately monthly intervals on permanent quadrats on a semi-exposed shore in SW-Iceland (lat. 64 degrees 11'N, long. 21 degrees 46'W). Good consistency between years was found in the seasonality of abundance for many common species. Most species start increasing their cover in March. at the same time that phytoplankton in the region begins blooming. The cover of many species starts decreasing more or less simultaneously in May, while some species, notably the fucoids, continue to increase into the autumn. The seasonal changes in cover correlate with changes in irradiance and nutrients but not with temperature.