SEASONAL DISTRIBUTION OF THE DINOFLAGELLATES IN THE MAR MENOR (MURCIA, SPAIN)

Abstract

The seasonal variation of dinoflagellates in Mar Menor (an inland sea connected with the Mediterranean) has been studied by the analysis of samples collected with a 52 um mesh size net. Moreover, it has been compared with that shown in a nearby locality in the Mediterranean Sea coast. A total of 198 species of dinoflagellates have been identified, 145 in the samples from Mar Menor and 165 in the ones from the Mediterranean coast. The most represented genera were Ceratium, Peridinium and Gonyaulax with 41, 37 and 16 species respectively in the samples from Mar Menor and 51, 31 and 16 in the ones from the Mediterranean Sea. In spring, a remarkable dominance of Ceratium furca was produced in both seas, with relative abundances, with respect to total phytoplankton, over 20% and furthermore over 50% in some occasions. In the other seasons the dominance of one species over the rest is not so clear, with the exception of midwinter when Peridinium paulseni reaches, in Mar Menor, relative densities of the order of 25%, being also abundant in the Mediterranean samples (4%). In summer there were the greatest differences on the dinoflagellate specific composition, between the two seas. Mar Menor was characterized by a series of Peridinium species, specially P. oceanicum (9%) and P. solidicorne (5%), while the most important species in the Mediterranean Sea were Goniodoma polydricum (8%) and Ceratium furca (6%). The highest diversity of dinoflagellate species and the Mediterranean sample had 86 different ones. At this time Ceratium pentagonum (8% in lblar Menor and 13% in Mediterranean Sea) was one of the most abundant species, together with Gonyaulax spinfera (1 0%) in Mar Menor and Ceratium declinatum (8%) in the Mediterranean samples.