THE GULF-OF-TEHUANTEPEC AND ADJACENT AREAS - SPATIAL AND TEMPORAL VARIATION OF SATELLITE-DERIVED PHOTOSYNTHETIC PIGMENTS

Photosynthetic pigment concentrations retrieved from data generated fr om 1978 to 1986 by the sensor Coastal Zone Color Scanner were used to describe the seasonal and interannual variation of phytoplankton bioma ss of the Gulf of Tehuantepec and adjacent areas. The pigment concentr ation 0.3 mg m(-3) and higher were considered as an index of productiv e waters. Its spatial coverage shows coastal upwelling in the gulfs of Tehuantepec and Papagayo (in the eastern region of the study area) be tween October and April, upwelling at the Costa Rica dome during summe r, and the transient effect of mixing by tropical storms from July to October throughout the study area. Upwelling events in Tehuantepec and Central America are not synchronous. The region west of the Gulf of T ehuantepec is oligotrophic most of the time (<0.2 mg m(-3)). The most evident interannual variation was the effect of El Nino 1982-1983, wit h very low pigment concentrations associated with a deep thermocline i n the whole study area. Also, there was an anti-El Nino event in 1985 in the eastern region, with high phytoplankton biomass concentrations associated with a shallow thermocline.