Díaz, M.C.; Smith, K.P.; Rützler, K. (2004). Species richness and abundance as indicators of mangrove epibenthic community health. Atoll Research Bulletin. 518, 2-17.
Díaz, M.C.; Smith, K.P.; Rützler, K.
Species richness and abundance as indicators of mangrove epibenthic community health
Atoll Research Bulletin
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In the Caribbean Sea, sponges are diverse and common colonizers of subtidal mangrove substrates such as aerial roots and peat banks. On the other hand, few species are widely distributed, whereas the majority is rare. Biodiversity studies should therefore cover appropriately sized survey areas to allow the encounter with species that have low population densities. h the characterization of sponge population structure at specific sites, it is preferable to use a large number of short transects rather than a few long ones. Trials conducted at mangrove islands on the southern Belize barrier reef platform show that surveying multiple transects of 15-20 m length along the fkinge of tidal channels (covering 50-70 stilt roots) reveal more than 90% of the epibiont species present at each site. We found that the majority of the widely distributed species are among the most frequent colonizers and their abundance, with the exception of a few, is maintained over at least a six-year period. Sponge species richness can serve as a bioindicator of subtidal community health as long as there are baseline data to determine its variation over time. However, this method is not suitable for comparing geographically distant mangrove systems. Common and widely distributed mangrove species, such as Haliclona manglaris, H. curacaoensis, H. implexiformis, Mycale magniraphidiphera, Clathria venosa, and Geodiapapyracea, and other generalist species, notably Tedania ignis, Hyrtios proteus, Spongia tubulifera, Chondrilla nucula, Mycale microsigmatosa, and Scopalina ruetzleri, may best reflect changes in the environmental conditions at particular sites. The families Chalinidae, order Haplosclerida (six Haliclona spp. and two Chalinula spp.), and Mycalidae, order Poecilosclerida (four Mycale spp.), include the most diversified taxa among mangrove sponge populations. Up to 20 percent of mangrove roots at Twin Cays harbored two or three Haliclona species each, whereas Mycale species were common but rarely two co-occurred on the same root. These families, in particular, are being investigated for their suitability as bio-indicators of mangrove health by evaluating changes in their population dynamics and responses to natural and anthropogenic ecological stress conditions.