Distribución y abundancia de los Thecosomata (Gastropoda) recolectados con red CalVET en agosto de 1985, frente a Bahía Magdalena, Baja California Sur, México

Abstract

The performance of the CalVET net for plankton studies was evaluated by analyzing the distribution and abundance of Thecosomata obtained with this net on August 1985 off Bahía Magdalena, Baja California Sur, México. The samples were obtained by vertically towing through the upper 100 m. Tows were made every 5 nm on transects perpendicular to the coast line. Each transect was separated by 10 nm. The eight species identified were: Limacina inflata and L. trochiformis, the most frequent and abundant; Creseis vírgula virgula and C. v. constricta, abundant but mainly limited to the north of the explored urea; Desmopterus pacificus, more abundant in coastal waters; Clio pyramidata, scarce and dispersad in the south; and Limacina helicina and Peraclis apicifulva, at very low densities at isolated stations. The species associations and their distribution patterns were determined using principal components analysis, dentified their relation to latitude, distance to the coast, water temperature, or to topographic features like the shelf-break zone, the mouths of the Bahía Magdalena Lagoon Complex, Cabo San Lázaro and bajo Petrel.