Primary productivity of phytoplankton estimated with the oxygen and carbon fourteen methods at one station of Estero de Punta Banda, Mexico

Abstract

 In order to estimate primary productivity of the phytoplankton using the dissolved oxygen (ΔO₂) method with different incubation times and to compare it with that estimated using the carbon fourteen (¹⁴C) method, simultaneous primary productivity experiments were carried out with both methods, on 12 November 1993, 3 and 16 February 1994, and 24 May 1994. The gross primary productivity (GPP) estimated with the ΔO₂, method was similar to the values derived from the ¹⁴C method, with α = 0.05. Furthermore, to know the variability of the chlorophyll concentration and bacteria1 abundance, sea water was collected every 30 min during the sampling period. We conclude that it is important to consider bacteria in studies that estimate primary productivity in coastal areas, since bacterial abundance affects the results of the ΔO₂, method, due to the utilization of the oxygen when there is enough substrate inside the bottles. The GPP values estimated with the ΔO₂ method can be recommended as viable alternatives to the ¹⁴C method for situations where it is not convenient or possible to use radioactive isotopes, provided that the experiments are accomplished with replicas and at least three final incubation times.