The pelagic copepod community of the oceanic area off the Mexican state of Tamaulipas was surveyed in June-July 1995 . During the period and area surveyed, two mesoscale gyres, a cyclone and an anticyclone, were detected. The influence of each was related to a particular area. A total of 106 copepod species was determined. Copepod density, diversity, and species richness differed between ¡he areas affected by the cyclone and the anticyclone. The overall density in the two areas was similar, but copepods at the cyc10ne nucleus were slightly denser than in ¡he anticyclonic nucleus. Diversity and species richness were higher at the relatívely more productive cyclone area. Antícyclones are oceanic, oligotrophic systems with a strong Caribbean influence, and the local copepod community structure, dominated by sorne of the mos! abundant species in the Caribbean, and with relatively lower diversity and species richness, seemed to agree with the anticyclone features. The copepod fauna of the cyclone, mainly built up by coromon Gulf water, showed a higher diversity and species richness, and a higher affinity with the fauna of the Gulf. The distributional range of several species is extended in this survey and sorne are report ed herein for the first time in the Gulf of Mexico.
Keywords: marine zooplankton, mesoscal e eddies, pelagic copepods