Characterization of a marine sublittoral area facing the open sea, using epibenthic protists

The biomass of the protist species present in a marine sublittoral area facing the open sea was studied throughout 1 yr. The following parameters were measured: temperature, pH, redox potential, salinity, conductivity, granulometry, phosphate, nitrate, nitrite, organic matter, dissolved oxygen and bacterial biomass. A total of 220 protist species was found, with a biomass of 191.17–1816.44 mgC m⁻³, the highest proportion corresponding to heterotrophs and, of these, to ciliates. Protist (36 species) were the most frequent: 14 flagellates, seven dinoflagellates and 15 ciliates. The abiotic factors most strongly affecting the distribution of these species were temperature, salinity, pH, granulometry, phosphate, nitrite, nitrate and organic matter. The data with respect to biomass of these 36 species, and those regarding the other parameters measured, allowed the division of the annual cycle into three periods characterized by certain protist species and physico-chemical conditions: (1) November–February, (2) March–July and (3) August–November.