Spatial and temporal changes in the nekton of the Terminos Lagoon, Campeche, Mexico

This study describes the current state of the nektonic communities in Terminos Lagoon in relation to the main environmental factors, and documents variations in number of fish species, dominance and abundance, compared to studies performed in 1980. Information on several environmental factors (temperature, salinity, oxygen, pH and transparency) in the Terminos Lagoon between October 1997 and March 1999 allowed the classification of the lagoon into five zones or subsystems. The hydrological characteristics of these subsystems showed spatial differences compared with studies carried out during the 1980s. During the study period, the number of fish species was 105, compared with 154 species reported in the 1980s. Five fish assemblages were identified and appeared to be associated with the five zones or subsystems. Five fish species considered important based on their abundance in the lagoon during the 1980s declined in numbers: pig fish Orthopristis chrysoptera , Atlantic croaker Micropogonias undulates , striped burrfish Chilomycterus schoepfi , spotted seatrout Cynoscion nebulosus and Gulf toadfish Opsanus beta . Six fish species, previously of minor importance, however, were very abundant: star drum Stellifer lanceolatus , Atlantic anchoveta Cetengraulis edentulus , gafftopsail catfish Bagre marinus , sand seatrout Cynoscion arenarius , striped mojarra Eugerres plumieri and ground croaker Bairdiella ronchus . Among the dominant species, the silver croaker Bairdiella chrysoura and the sea bream Archosargus rhomboidalis experienced significant changes in average abundance and distribution patterns. These changes were probably related to the impact of human activities in the Terminos Lagoon and natural variability.