Seasonal variation of ichthyoplankton in a western Caribbean bay system

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The plankton of Bahia de la Ascension was sampled monthly, from August 1990 to July 1991, to ascertain ichthyoplankton composition, abundance, and seasonality. These data were used to assess the inferred function of the bay as spawning and nursery grounds. Fifty-one families, 66 genera, and 53 species of fish embryos and larvae were identified. Engraulidae, Clupeidae, Labrisomidae, Callionymidae, Gerreidae, and Gobiidae comprised 81.5% of the larvae captured: the remaining 18.5% included several coral reef fish families. Greatest mean fish egg densities were recorded between December and April, 341-246 per 100m3, suggesting a major spawning period. The monthly mean density of total fish embryos and larvae showed two peaks: one in late dry season (June), dominated by newly hatched engraulid, and a second (December) during the cold-front season with high densities of preflexion labrisomid and engraulid embryos. When labrisomid and engraulid embryos and larvae were excluded, densities peaked in the rainy season (July to October). Gerreidae and Callionymidae were significantly more abundant in the rainy season, while Labrisomidae and Gobiidae in the cold-front season. The highest embryos and larvae richness was observed in August during the rainy season with mean value significatively greater than those from cold-front and dry seasons. The occurrence of high egg densities and the wide range of embryos and larva stages are evidences that Bahia de la Ascension is a regionally important spawning and nursery ground for marine fish. Because this study covered partially the marine ecosystem of Bahia de la Ascension using convential gear, we suggest to conduct further research for have a full understanding of the importance of this bay for fish recruitment. eng