Copepod assemblages from a reef-related environment in the Mexican Caribbean Sea

Results on copepod composition and abundance from samples obtained in a reef zone in the northern part of the Mexican Caribbean Sea are presented here. Samples were collected monthly from June to December 1991 at four stations, two of them in the reef lagoon and two at the fore-reef. Salinity and temperature were homogeneous at the four sampling sites. Copepods in the lagoon showed a higher abundance, lower species richness and a clear dominance of Acartia spinata. Copepods outside the lagoon were less abundant, but with a larger number of species. Acartia spinata and Farranula gracilis were the most conspicuous species, the former being the dominant form of the reef lagoon community and the latter so at the adjacent sea stations. The local distribution of Undinula vulgaris seems to be related to the extent of oceanic influence throughout the coastal-oceanic gradient. The reef-associated copepod community shows a strong neritic-oceanic affinity, which is related to the narrowness of the shelf, the local hydrodynamics, and the wind regime. The Bray-Curtis Index clustered the stations with similar features in several different ways during the survey. Despite these month-to-month differences, the general behaviour of the local copepod community seems to be quite homogeneous when compared with other reef systems. This effect could be related to the circulation pattern in the area, which favours a continuous, strong oceanic influence along the reef.