A study was carried in a sector of the coast of Aguadulce between Estero Palo Blanco and Estero Salado in the dry season of 2015. Three sampling stations named Palo Blanco, La Torre y El Salado were established. At each station, three surface samples of 500 ml each were taken using a Van Dorn bottle and analyzed spectrophotometrically for chlorophyll a, b and c. Readings of salinity and transparency were recorded using a hand refractometer and a Secchi disk. Salinity was higher at La Torre station (36.0 ppm) and lower at Palo Blanco (34.5 ppm) and El Salado (34.8 ppm). Lower water transparences were found at Palo Blanco (extinction coefficient 4.02) while La Torre and El Salado showed higher values (extinction coefficients 1.42 y 1.96 respectively). Amounts of the chlorophyll -a varied from non-detectable levels to 12.6 mg m3. The highest monthly averages were registered at the mouth of the Palo Blanco and El Salado estuaries (7.7 mg m3 and 5.4 mg m3 respectively) with high values in the months of March, April and May when the first winter rains begin to fall. Chlorophyll b values ??were lower, and the mean monthly varied little between sampling stations (0.5 mg m-3 for Palo Blanco estuary, 0.6 mg m-3 for La Torre and 0.4 mg m-3 for El Salado estuary). The highest mean values ??of chlorophyll c were observed at the Palo Blanco (4.0 mg m-3) while La Torre and El Salado showed lower values (2.0 mg m-3 and 2.4 mg m-3 respectively). The values found in the present study were higher than those reported for the Gulf of Panama in the coastal upwelling period, although they are within what is expected for an area where interact different oceanographic patterns.
