Composition and spatial distribution of the zooplankton community in the Mexican Caribbean ecosystem during the 2025 spring season.

Introduction: The marine and coastal ecosystems of the Mexican Caribbean are recognized for their high biodiversity and ecological importance. Zooplankton, as a key component of the food web, plays an essential role in ecological balance. However, environmental factors such as climate change, pollution, and habitat alteration generate uncertainty about its dynamics and distribution. This study aimed to characterize the structure and spatial variation of the zooplankton community off the coast of Quintana Roo during the spring of 2025, using a continuous high-resolution sampling method (CUFES).

Methods: Continuous sampling transects were conducted between May and June 2025 in Mexico's exclusive economic zone. Surface organisms were collected using the CUFES system, and environmental variables (temperature, salinity, currents) were recorded with oceanographic sensors. Data were statistically analyzed to compare abundance and richness between areas influenced by the Yucatan and Cayman.

Results: Forty-nine samples were obtained, grouped into 15 main zooplankton categories. Copepods were the dominant species (approximately 78% of total abundance), followed by shrimp larvae, crab larvae, pteropods, and chaetognaths. Abundance was significantly higher in the In Current zone (approximately 1042 individuals/sample) compared to the Out Current zone (approximately 727 individuals/sample), although species richness showed only a marginal trend toward significant differences. Spatial distribution revealed marked heterogeneity, with aggregations of fish eggs and larvae in areas of higher surface temperature.

Conclusions: The zooplankton community of the Mexican Caribbean is characterized by the dominance of copepods and the significant presence of decapods, pteropods, and chaetognaths. Ocean currents appear to favor greater abundance and relative diversity, although the effect is moderate. These results provide a basis for future monitoring and conservation studies, especially in the context of increasing environmental impacts such as the massive influx of sargassum.