In this study, a comparison of the fish larvae community structure of two estuarine systems throughout an annual cycle is presented. Information concerning the Forleague Bay, Louisiana, in the northern Gulf of Mexico, originates from bibliographical sources1. For the tropical system of coastal lagoons of the Sian Ka'an Biosphere Reserve in the Caribbean Sea, surface simultaneous towings with plankton nets of 200-um and 500-um mesh were obtained in four climatic periods, from October 1996 to August 1997.
Forleague Bay, in central Louisiana, is a site of mixing between the nutrient-rich Atchafalaya River-derived waters of the upper bay and the coastal ocean waters, producing a large salinity, chlorophyll a, and primary productivity spatial gradients. In the temporal scale, Forleague Bay also exhibits strong temperature variations (10.2 to 30.9 °C). In this system, warm water species (e.g. Anchoa mitchilli, Gobiosoma bosci, Microgobius sp., Cynoscion nebulosus, and Gobiesox strumosus) dominated in water temperatures >23 °C. The cooler water species (e.g. Brevoortia patronus and Micropogonias undulatus) dominated in water temperatures <23 °C (Raynie and Shaw, 1994).
In the Mexican Caribbean, the Campechén, Boca Paila, San Miguel, and La Ría lagoons constitute the semi-enclosed system of the northern section of the Sian Ka'an Biosphere Reserve. These shallow bodies of water show high water temperatures throughout the year (> 25.5 °C) and a strong spatial gradient of salinity in La Ría (12 to 35 ‰), which is highly influenced by the adjacent marine waters. In these systems, two main groups basically composed the ichthyoplankton community. The first one, located in southern portion of La Ría, comprises oceanic species (e.g. Callionymus sp., Opisthonema oglinum, Brevoortia sp., and Jenkinsia lamprotaenia). The other group, found lengthwise the studied area, includes lagoonal species (e.g. Gobiidae, A. hepsetus, Microgobius sp., Membras martinica, Syngnathus scovelli, and Lupinoblennius nicholsi).
The comparative analysis of the ichthyoplankton communities of both
estuaries showed that spatial variations are stronger in the Mexican Caribbean
system, while seasonal fluctuations are more intense in the northern region
of the Gulf of Mexico suggesting a differential utilization of resources
in dissimilar locations and times