Microphytoplankton variations during coral spawning at Los Roques, Southern Caribbean.

摘要: Phytoplankton drives primary productivity in marine pelagic systems. This is also true for the oligotrophic waters coral reefs, where natural and anthropogenic sources of nutrients can alter trophic webs. In this study, microphytoplankton assemblages were characterized first time relation to expected spawning dates Caribbean. A hierarchical experimental design was used examine these Los Roques archipelago, Venezuela, at various temporal spatial scales events both 2007 2008. At four superficial water samples taken daily 9 days after full moon August, including before, during spawning. Microphytoplankton comprised 100 microalgae taxa up 50 cells per mL (mean ± 8 SD) showed variations related only 2007. However, chlorophyll a concentrations increased years, better matched with analyses higher taxonomical groups (diatoms, cyanophytes dinoflagellates), that varied times 2008, but asynchronously among reefs. Heterotrophic mixotrophic dinoflagellates abundance, correlating decrease diatom Cerataulina pelagica an increase Rhizosolenia imbricata. These occurred event some reefs For time, fresh-water cyanobacteria species Anabaena ephemerally found (only 3 days) closest human settlements. Variability indicated reef-specific processes such as residence re-mineralization rates, benthic-pelagic coupling be relevant observed patterns. results suggest important role microheterotrophic grazers organic matter reef highlight importance assessing compositional changes larger size fractions phytoplankton when evaluating nutrient fluxes.