| Resumo: |
ABSTRACT In the southern Caribbean, there are two main upwelling areas, the Colombian Guajira and eastern Venezuela. However, fishing production is highly dissimilar, even though in the Guajira the wind intensity is stronger and theoretically the upwelling is more intense. For this reason, it should have a higher fishing production than Venezuela, which is not the case. The possible reasons for this important difference are presented, detailing aspects related to wind, hydrography, nutrient concentration, phytoplankton biomass, continental shelf, river contribution, island presence and other factors. Eastern Venezuela has greater fertility and fishing production because the Subtropical Subsuperficial Water mass is what supplies the water upwelling during the first months of the year (dry season). In the second semester, when the upwelling relaxes, the area is enriched with organic matter from the Orinoco River and the contribution of phytoplankton biomass from coastal lagoons, inlets, and partially closed bays. The wide extension of the continental shelf, with the presence of archipelagos, large islands, and islets that cause local enrichment and the plankton concentration and retention also plays a fundamental role. The latter increases biological productivity and support plankton reproduction. On the other hand, Colombian Guajira upwelling water may be influenced by the Darien Countercurrent, which, by its origin, should be poor in inorganic nutrients; furthermore, this region lacks important rivers that contribute organic matter and the Guajira continental shelf is rather narrow and does not contain islands that may help to increase aquatic productivity. In order to understand Guajira upwelling it is necessary to follow its hydrography in situ, as well as inorganic nutrients, chlorophyll, and phytoplankton and zooplankton abundances.
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