The copepod community (Crustacea) in middle scale swirls of the western Gulf of Mexico (July, 1995)

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 surve yed, 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 di ffered between the areas affected by the cyclone and the anticyclone. The o verall density in the two areas was similar, but copepods at the cyclone nu cleus were slightly denser than in the anticyclonic nucleus. Diversity and species richness were higher at the relatively more productive cyclone area . Anticyclones are oceanic, oligotrophic systems with a strong Caribbean in fluence, and the local copepod community structure, dominated by some of th e most abundant species in the Caribbean, and with relatively lower diversi ty and species richness, seemed to agree with the anticyclone features. The copepod fauna of the cyclone, mainly built up by common Gulf water, showed a higher diversity and species richness, and a higher affinity with the fa una of the Gulf. The distributional range of several species is extended in this survey and some are reported herein for the first time in the Gulf of Mexico.