Spatiotemporal analysis of micronekton biomass at the mouth of the River Plate

The region adjacent to the River Plate is renowned for its fishing activity and abundant biodiversity. Both are closely linked to the significant local river flows responsible for fertilizing extensive marine areas. Among the several biological communities, micronekton deserves special attention as it serves as a vital trophic link between primary production and top predators in the ecosystem. Recognizing its importance, this study evaluates the spatio temporal variability of epipelagic micronekton biomass at the mouth of the River Plate. Numerical modeling outputs of micronekton functional groups were obtained from the Spatial Ecosystem and Population Dynamics Model (SEAPODYM), coupled with in situ environmental data (precipitation, wind direction, and intensity) from 2015 to 2019. The results revealed greater aggregations of epipelagic micronekton near the river mouth. There was a seasonal disparity in micronekton biomass in the zone influenced by river drainage, with higher biomass values observed during the summer and lower values during the winter. This seasonal difference was attributed to winds from the northeast and southeast quadrants, as the micronektonic plume is susceptible to their effects. However, precipitation data did not exhibit a significant correlation with in situ flow data nor with quantitative micronekton measurements. This discrepancy may be attributed to the positioning of the data collection stations relative to the dimensions of the mouth of the River Plate.