The Chaetognatha of the Southwestern Gulf of Mexico During April-May, 1986

Abstract

An analysis of the distribution and abundance of Chaetognatha species from the Gulf of Mexico during April–May 1986 is presented. Zooplankton samples were collected at 43 stations from the southwestern and eastern regions of Mexico’s Exclusive Economic Zone in the Gulf of Mexico. Species richness and abundance were higher in the southwestern stations located at the platform slope. The rank of Importance Value (IV) shows 3 groups of species; the first group included Flaccisagitta enflata, Mesosagitta minima, Serratosagitta serratodentata, Krohnitta subtilis, Pterosagitta draco, Sagitta bipunctata, and Krohnitta pacifica which were the most widely distributed species during this period. Density data were classified and analyzed by Morisita’s similarity index, depicting 2 large groups of sampling stations along with a third group made up of 5 stations. Two stations were distinct from the others because of the low species richness and because only 2 species with high densities were present. Simpson’s dominance index showed low values throughout the study area. Densities of chaetognath species did not differ significantly between day and night samples. Gulf and Caribbean Research Vol. 13, 51–57, 2001 Manuscript received July 14, 2000; accepted February 9, 2001