Abstract

ARAYA-VARGAS, Alexander et al. Evaluation of the community structure of marine sponges in reef patches of the southern Caribbean, Costa Rica. Bol. Invest. Mar. Cost. [online]. 2020, vol.49, n.1, pp.39-62. ISSN 0122-9761.  https://doi.org/10.25268/bimc.invemar.2020.49.1.773.

Marine sponges fulfill many critical functions to coral reefs. In turn, variations in the community structure of the poriferans may indicate changes in the environmental conditions of the ecosystems where they live. However, their study has been scarce in the Caribbean of Costa Rica, mainly in the ecological field. Therefore, the community structure of these organisms was evaluated in four reef patches (Perezoso, Pequeño, Coral Garden, and the 0.36) and it was determined whether it could be explained by sedimentation, substrate, and depth. Relative abundance (RA) and relative coverage (RC) for each species, sponge density, and diversity indices (species richness, Shannon heterogeneity, Pielou's evenness, and Simpson's dominance) were calculated for each sampling site. Similarity between sites was compared to the relative abundance of sponges versus sedimentation, substrate, and depth. 13 new sponge records were found for the country. Perezoso had the highest sponge coverage (RC = 6.1 %) composed mainly by Cliona caribbaea (RC = 2.0 %) and with Niphates erecta as the dominant species (RA = 59.3 %). Species richness increased as site depth increased. Perezoso and Coral Garden showed the biggest similarity in terms of species abundance and shared N. erecta, Iotrochota birotulata and Scopalina ruetzleri as the most abundant species. These sites also shared the highest occurrence frequencies (40 %) of excavating sponges of the genus Siphonodictyon and the presence of the boring species C. caribbaea. Similarity between Perezoso and Coral Garden could be influenced to a greater extent by the high availability of calcareous pavement as a predominant substrate (48 < PC % < 67), which seems to favor the abundance of heterotrophic and generalist sponges, as well as that of excavating species and boring sponges.

Keywords : Porifera; coral reef; sedimentation; substrate; depth.

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