Hyperiid Amphipods (Crustacea: Peracarida) and Spring Mesoscale Features in the Gulf of Mexico

Abstract. The distribution and abundance of the hyperiid amphipods collected during April–May 1986 was analysed in order to study their relationship to mesoscale features in the southern Gulf of Mexico. Hyperiids were represented by 79 species, Lestrigonus bengalensis (65% of total hyperiids), Primno abyssalis (4.3%), Anchylomera blossevillei (2.3%) and Lestrigonus schizogeneios (2.3%) being the most abundant. Several mesoscale features (two cyclonic and three anticyclonic eddies, two upwelling areas) were active in the surveyed area. Cluster analysis of density and composition produced five groups of stations that were found to be related to some of these features. Overall, the mesoscale features that most influenced the local hyperiid community were the upwelling areas; they were related both with the highest and the lowest hyperiid densities and with high and low diversity figures. Overall day/night variations were normal, with highest night‐time densities; this pattern was not consistent in the different mesoscale features studied. Reverse migrations were possibly occurring, or migration patterns were lacking, at some of these systems. The hyperiid community structure related to the anticyclonic eddies differed somewhat among the eddies; however, the oceanographic exchange with the surrounding gulf waters probably obscured sharper faunistic differences between the communities.