PIGMENTOS CLOROFILICOS E HIDROGRAFIA EN LA REGION NOROCCIDENTAL DE VENEZUELA CON ENFASIS EN EL GOLFO DE VENEZUELA

Abstract

Four oceanographic expeditions were carried out from 1982 to 1984. These surveys evaluated chlorophyll - a and pheopigments concentrations in surface waters of the "Golfo de Venezuela" and adjacent regions. Also, physical and chemical parameters were measured in order to locate the upwelling zones and the area where mixing with "Lago de Maracaibo" water is occurring. A total 424 surface samples taken every 20 miles (36 km aprox.) were analysed by Lorenzen,s (1967) method, obtaining values of chlorophyU-a and pheopigments ranging from less than 0.1 mg/m3 up to 5.2 mg/mi . During the first three surveys, a normal behavior of the Trade winds was observed; they blew from east to west, although they showed occasional variability. The winds induced strong upwellings on the western coast of the "Peninsula de Paraguaná" and in the "Golfete de Coro", both areas showing high chlorophyll concentrations. Mixing of "Golfo de Venezuela" with "Lagode Maracaibo" waters, which had low concentration values, was observed in the "Bahía de Calabozo", South of the "Península de la Guajira". Otherwise, the wind changed considerably during October and November of 1984; its speed decreased and its direction changed 180° bringing about an alteration of water dynamics in the upwelling zone as well as in the mixing area. During this period chlorophyll values were low.