Spatial distribution of zooplankton in the salinity gradient between the Dos Bocas port and the Mecoacan lagoon, Tabasco

Abstract

Background: The importance of the port of Dos Bocas, Tabasco, for the oil industry in the southern Gulf of Mexico, contrasts with the scarce information on the zooplankton community in its surroundings. Objectives: Generate baseline information on the spatial distribution of richness, abundance and holoplankton/meroplankton (H/M) ratio of zooplankton groups (ZG) along the salinity gradient. Methods: In October 2016, one sampling was conducted at 17 sites in the coastal area adjacent to the Dos Bocas port and the Mecoacan Lagoon. The biological samples were obtained using a plankton net with a 300 μm filtering mesh, recording water salinity and temperature. Results: The richness, abundance, and H/M ratio decreased with salinity. The coastal zone was characterized as a euhaline environment, where 26 ZG were recorded, with a mean abundance of 3,880 ind 100 m-3 and H/M ratio = 11.3, with copepods being the dominant group, which is indicative of the secondary productivity associated with the coastal environment. In the Mecoacan Lagoon, a meso-polyhaline environment predominated, where 17 ZG were recorded, with a mean abundance of 409 ind 100 m-3 and H/M ratio = 1.8, with fish eggs being the dominant group, which is indicative of the importance of the Mecoacan Lagoon for species with commercial or ecological importance, before their adult stage. Conclusions: The changes in the richness and abundance of zooplankton taxa along the salinity gradient provide baseline information on the differential use of the Mecoacan Lagoon and the adjacent coast by ZG with distinct life cycles, representing the first contribution to the knowledge of zooplankton in the study area.