Microalgae from the mucus layer of two massive corals: more than sunken plankton

The mucus of scleractinian corals harbors a variety of prokaryotic and eukaryotic microorganisms, but little is known about the eukaryotic fraction of this microbiota. In this study, a quantitative and qualitative description of microalgae assemblages associated with the mucus of two species of massive corals is presented. During the first half of 2004, in “Los Frailes” Archipelago (Southern Caribbean), samples of mucus were randomly taken from healthy colonies of Diploria sp. and Colpophyllia sp. Also, samples of water surrounding each colony were taken monthly for six months. Multivariate analysis showed that microalgae assemblages from the mucus were significantly different from those found in the water column, and that variation of microalgae assemblage composition in time was dependent on the coral species. The results indicate that most of the microalgae assemblage associated with the mucus did not originate from a passive trapping of species commonly found in the phytoplankton. Nevertheless, temporal variations of both assemblages (i.e., phytoplankton and mucus) were very dynamic but closely associated.