SPATIAL DISTRIBUTION OF ZOOPLANKTONIC ACOUSTIC BIOMASS AND ITS RELATIONSHIP WITH OCEANOGRAPHIC VARIABLES UNDER DIFFERENT UPWELLING REGIMES IN LA GUAJIRA, COLOMBIAN CARIBBEAN

The distribution of zooplankton biomass in the upwelling system of La Guajira (Caribbean Sea), was evaluated using more than 800 linear km of acoustic data obtained from two samplings conducted in 2018 during a period of weak (May) and intense (December) upwelling. Modeling of the spatial variability and interpolation of zooplankton acoustic biomass was performed using a geostatistical method and its relationship with environmental variables through generalized additive models. It was found that the spatial distribution of zooplankton acoustic biomass was different in the two periods evaluated. In May it was concentrated on the edge of the continental shelf and in December it was associated with upwelling foci or areas with high fluvial inputs from the Magdalena River (Gulf of Salamanca). In the weak upwelling period, zooplankton biomass was higher and was associated with high dissolved oxygen concentrations and low chlorophyll-a levels. The seasonal variability of zooplankton biomass does not show a linear relationship with upwelling intensity, probably as a consequence of air-ocean-river interaction processes affecting the region.