Patrones de distribución de clorofila a y producción primaria en aguas del Golfo de México y del Mar Caribe

Abstract

An aceanographic cruise was carried out in the Summer 1994 in the Gulf of Mexico and Caribbean Sea in order to study the spatial variability (horizontal and vertical) of the total chlorophyll a and primary production in relation to thermal structure, irradiance, and the nutricline position in the water column. The highest production rates were measured on the Yucatan shelf (0.84 and 2.11 gC.m-2.d-1) while in the Gulf of Mexico and Caribbeab Sea the rates were much lower (0.07-0.14 gC.m-2.d-1). Vertical profiles with deep chlorophyll maxima (0.16 to 4.24 mg.m-3) were always situated below the mixed layer, between 20 and 120m deep in neritic and oceanic waters, respectively, at low light intensities (between 0.2 and 5% of I) and sometimes in relation to the nutricline. In the Gulf of Mexico and in the Caribbean Sea a vertical profile types which is characteristics for tropical oligotrophic waters, with low chlorophyll concentrations, a deep maximum near the nutricline and low primary production was found. In the Yucatan shelf the profile approximates to the productive extreme of typical tropical structure, with higher chlorophyll concentration, primary production and a shallow thermocline. In oligotrophic waters the phytoplankton fraction < 10um contributes with 50 to 100% of the total chlorophyllic biomass while, in eutrophic waters its contribution ranges between 20 and 67%.