Structure and seasonal variation of the Ichthyoplankton community from a hypersaline lagoon in the Western Gulf of Mexico: Laguna Madre, Tamaulipas

Abstract

In order to analyze the structure of the Ichthyoplankton community in the southern region of the Laguna Madre, Tamaulipas, zooplankton samples were taken in October of 1997, and January, May and July of 1998; salinity and temperature (°C) of the superficial water were simultaneously measured. Thirthy nine species were identified: Opisthonema oglinum, Lupinoblennius nicholsi, Ctenogobius shufeldti, Microgobius thalassinus, Gobiesox strumosus, Citharichthys arctifrons and Acanthostracion quadricornis were new records to the system. 80% of the species were marine; these penetrate the
system in their larva and/or young stage and make use of the system as a nursery zone. The highest abundance of larvae was found in May (ANOVA3, 76 F= 4.995, p < 0.005). Anchoa hepsetus and Anchoa mitchilli were present all year round; the latter represented 55.8% of the total population. There was a positive correlation between the density (no. of larvae/100 m3) of A. mitchilli with the temperature (rs (?=0.001) = 0.376) and salinity (rs (?=0.001)= 0.467). Anchoa hepsetus and Brevoortia gunteri presented a negative correlation with the temperature (rs (?=0.001) = -0.247 and rs (?=0.001)= -0.567, respectively). The richness of species was greater in May and July (24 and 21, respectively). The diversity was lower in October (1.40 bits/ind) and May (1.02 bits/ind) and greater in July (2.23 bits/ind), as well as in equity (0.50). The highest values of dominance were present in October and May (0.57 and 0.59, respectively). Eight groups of species were formed by the Bray-Curtis dissimilarity index, which determines if the structure of the community is formed by typical lagoon species or estuarine-dependent species.