Diversity, Seasonal and Diel Distribution Patterns of Anchovies (Osteichthyes) in a Protected Tropical Lagoon in the Southwestern Gulf of Mexico

Anchovies are species of ecological and economic importance that inhabit coastal waters, where they are very abundant. The objective of the study was, through high-frequency temporal sampling, to analyze the diversity, seasonal and diel distribution patterns of anchovies and their relationships with environmental variables. For 19 months, 24-h monthly cycles were carried out, taking samples every two hours. Permutational analysis of variance (PERMANOVA) and redundancy analysis (RDA) were used for data analysis. Seven species were captured, of which, Anchoa mitchilli, Anchoa hepsetus, Anchoa lyolepis, Anchoa lamprotaenia and Cetengraulis edentulus are common in brackish waters; however, Anchoviella perfasciata and Engraulis eurystole rarely occur in these systems. For these species, no major threats are known; therefore, they are listed as ‘Least Concern’. A seasonal succession shows pulses during the closed-mouth phase and during the late warm-rainy season. At diel level, A. mitchilli, C. edentulus and A. lamprotaenia showed a markedly nocturnal pattern. RDA correlations showed that salinity, day/night effect, inlet state and rainfall were the most important factors related to anchovy distribution. Segregation along a salinity gradient was observed, in which A. mitchilli was captured mainly at low salinities, while other species occurred mainly at intermediate to high salinities. High-frequency sampling allowed a better understanding of the species richness and abundance patterns of anchovies in the system.