MOLLUSCS ASSOCIATED WITH MACROALGAE ASSEMBLAGES ON THE ROCKY COASTLINE OF CÓRDOBA, COLOMBIAN CARIBBEAN

Abstract

The composition and abundance of the benthic community of mollusks associated to macroalgal assemblages was studied in two ecoregions of the coastal strip of the Córdoba Province, Colombian Caribbean. Between September 2006 and June 2007 four samplings were done in six stations; three in San Antero, two in Puerto Escondido, and one in Los Córdobas. A quadrant of 625 cm2 with five replicates was used in order to collect the material; it was arranged randomly in each sampling period. A total of 1012 specimens and 68 species of mollusks were identified (46 gastropods, 19 bivalves, two polyplacophorans, and one scaphopod). The most abundant species in the Morrosquillo ecoregion were Bittiolum varium (34.95%), Parvanachis obesa (13.69%), Isognomon alatus (12.43%), and Columbella mercatoria (7.93%), while in the Darien ecoregion they were Eulithidium tessellatum (38.29%), E. affine (19.04%), C. mercatoria (7%), I. alatus (5.91%), and Tegula viridula (5.69%). There were significant differences between the macroalgal cover (Fs = 71.2, p < 0.001) and mollusk abundance (Fs = 56.9, p < 0.001) to the sampling stations (α = 0.05). The Principal Component Analysis (PCA) showed that the abundances of P. obesa, B. varium, I. alatus, and C. mercatoria is regulated by differences in coverage of the family Gracilariaceae in Morrosquillo ecoregion, while the abundance of E. affine, E. tessellatum, and T. viridula is regulated by changes in coverage of Sargassum polyceratium and Bryothamnion triquetrum in Darien ecoregion.