Assessing the Spatiotemporal Relationship between Coastal Habitats and Fish Assemblages at Two Neotropical Estuaries of the Mexican Pacific

Differences in fish assemblages' structures and their relations with environmental variables (due to the variations in sampled seasons, habitats, and zones) were analyzed in two adjacent estuaries on the north Pacific coast of Mexico. Environmental variables and fish catches were registered monthly between August 2018 and October 2020. Multivariate analyses were conducted to define habitats and zones based on their environmental characteristics, and the effect of this variability on fish assemblages' composition, biomass, and diversity (alpha and beta) was evaluated. A total of 12,008 fish individuals of 143 species were collected using different fishing nets. Multivariate analyses indicated that fish assemblages' structures were different between zones due to the presence, height, and coverage of distinct mangrove species. Additionally, depth and salinity showed effects on fish assemblages' diversity (alpha and beta-nestedness), which presented higher values in the ocean and remained similar in the rest of the analyzed zones and habitats. These results and the differences in species replacement (beta-turnover) indicate the singularity of fish assemblages at estuaries (even in areas close to the ocean) and the necessity to establish local management strategies for these ecosystems.

Automated summary

This study analyzed the structures of fish assemblages and their relationships with environmental variables in two adjacent estuaries on the north Pacific coast of Mexico. The results showed that habitat characteristics significantly influenced the composition, biomass, and diversity of fish assemblages. The depth and salinity also played a role in the diversity of fish assemblages. These findings highlight the singularity of fish assemblages in estuaries and emphasize the importance of local management strategies for these ecosystems.