TROPHIC CLASSIFICATION AND TEMPORAL KINETICS OF P/B, P/R, R/B AND NPP/GPP RATIOS IN THE PHOTIC LAYER OF THE DAM ZONE IN AN EQUATORIAL COLOMBIAN RESERVOIR

Abstract

We studied the kinetic temporal and trophic classification of the reasons P/B, P/R, NPP/GPP and R/B in the area of ??the dam reservoir Riogrande II (6o 35’ 57’’- 6o 28’ 79’’ N; 75o 32’ 17’’-75o 25’ 85’’ O). We measured gross primary production (GPP) and net (NPP) and respiration (R) at five depths within the photic zone. Samples were taken every month between July 2002 and June 2003. Phytoplankton biomass (B) is quantified according to Sartory & Grobbellar (1984) in samples integrated within the photic zone. From the maximum values of the profiles GPP and R were established photosynthetic Coefficient (GPPmax / B), the reason GPPmax / Rmax and metabolic coefficient (Rmax / B). The ratio between the mean values ??of NPP and GPP shows that NPP was 5.2 times GPP, reflecting higher R. These considerations imply that: the biomass present structure remains due to the negentropy relatively high, and metabolically the system is more autotrophic that heterotrophic, behaving as a carbon sink. Therefore, part of the biomass is breathe not in this ecosystem. implying that there is a PPN available, functioning as a nutrient trap of type autotrophic. The metabolic coefficient ranged around the unit, confirming the relative stability of the phytoplankton assemblage, with some catabolic periods, but prioritizing the anabolic character, what effectively converts the system into a carbon sink capable of maintaining stable condition, and therefore contributions resistant entropic or anergic. Assuming that an accumulation B signifies a R increase, then P/R must be less than one. However, the ratio P/R, with an average value of 1.61 shows clearly an imbalance between the produced material and the removed or consumed by R. Considering the concentration of phytoplankton B (17.1 +11.7 MgCl. Am -3 ), the dam of the water body studied is eutrophic. The mean values ??of the coefficient of Assimilation confirm this condition.