Spatial and seasonal variability of Acartia (Copepoda) in a tropical coastal lagoon of the southern Gulf of Mexico

In this study, the seasonal variability of the distribution and abundance of the copepod Acartia spp. in a coastal lagoon on the northern coast of the Yucatan Peninsula, Mexico, was analyzed during representative months of the three main seasons (dry, rainy, and northerlies=nortes) of an annual cycle. Also, two distinct areas of the lagoon (inner and outer) were revealed according to salinities and zooplankton biomass. Acartia lilljeborgii and A. tonsa were the most abundant species, representing together up to 95.5% of the overall abundance of the genus. More than half (52.3%) of the total abundance of A. tonsa occurred in the rainy season, 30.6% during nortes, and 17.1% in the dry season. Corresponding seasonal values for A. lilljeborgii were 57% in the dry season, 21.3% in the rainy season, and 20.4 in nortes. Up to 85% of the individuals of A. spinata occurred during nortes. Only in the dry season A. tonsa was most abundant species at the inner zone, whereas A. lilljeborgii was dominant in the outer zone during the same season. The correlation analysis revealed seasonal changes in the way that species of Acartia relate to different biotic and abiotic factors: Acartia tonsa and A. spinata showed significant differences related to the season and the former species to the combination of zone (inner-outer) and season. The spatial and temporal variation of Acartia species abundance was related to seasonal changes of the hydro-biological conditions of the lagoon. Hence, the local and small scale changes, together with the seasonal conditions and the response of these species to them, favor their coexistence in this lagoon system.