Spatial variation of medusan community (Cnidaria) in the Southern Gulf of Mexico, during autumn 1999

Abstract

The spatial variation of the jellyfish community during fall of 1999 in the southern region of the Gulf of Mexico was analyzed. Plankton material was collected through superficial Bongo-type net tows at 69 sites. Thirty-eight species of jellyfish (35 hydromedusae, two scyphomedusae and one cubomedusa) were found. Liriope tetraphylla was the dominant species, representing 78% of the collected fauna. Other important species due to their abundance were Cunina octonaria, Clytia folleata, Aglaura hemistoma, Solmundella bitentaculata, Pegantha triloba and Octophialucium medium. Six of the identified species are new records for the southern region of the Gulf of Mexico. The distribution of the most abundant species indicated a great concentration of organisms in the shallow waters of Campeche Bank. However, others like Nausithoe punctata and Euphysora gracilis showed their greatest abundances across the stretch continental shelf of the States of Veracruz and Tabasco. The dominant species acted as a community structure stabilizer, but less abundant species better denoted abundance changes in the community in particular oceanographic zones. In this sense, the spatial variation of the community structural components in the autumn season was related to the main oceanographic currents in the continental shelf and food availability.