Effects of red tides on oxygen concentration and distribution in the Golfo de Nicoya, Costa Rica

Abstract

 A one year study (April 1978-March 1979) in the inner section of lhe Golfo de Nicoya (100 N, 850 W), Costa Rica, revealed that red tides in this shallow « 20 m) region are most common during the dry and at the beginning of the rainy season, but may also occur during the later par! of the wet season.The massive occurrence of red lides in distinct patches strongly influences the temporal and spatial concentration of dissolved qxygen, (02 saturation values of up to 200 % were observed).Gross primary productivity in the presence of a red tide amounted to 0.64 g C m-2 h-I.The productive layer was restricted to the upper 2 m due to massive concentration of the algae near the surface and intensive self-shading.