Variation of biometric parameters and C, N, and P concentrations of Oryza glumaepatula at different depths of an amazonian lake impacted by bauxite tailings (Lake Batata, Pará, Brazil)

Abstract

Lake Batata is a typical Amazonian clear water lake which has undergone anthropogenic impacts. Thirty percent of its total area has been covered with bauxite tailings. Thus, it is possible to distinguish two areas in this ecosystem: the impacted and the natural. The goal of this research was to study C, N, and P content variation and the values of biomass, length, density, and culm diameter of Oryza glumaepatula at different depths in the natural and impacted areas of Lake Batata. The results obtained in this research suggest that the availability of P and N, in both water and sediment, is lower at the shallow site when compared to the deeper sites. On the other hand, C concentrations decreased as P and N concentrations increased. This may be explained by the structural function of C in aquatic macrophytes. At shallower sites, due to the reduced water column, individuals invest in supporting structures that display high C concentrations. The higher density and biomass of O. glumaepatula at the intermediate site indicate that this area presents the best conditions for germination and establishment of individuals of this species. The chemical composition and biometric parameters of O. glumaepatula have shown that this population has higher spatial variation in the natural area. In the impacted area, the absence of significant variations in N and P concentrations in O. glumaepatula among the three sampled sites promotes higher homogeneity in the stands. The high C:P and N:P ratios indicate that, in the impacted area, P is more limiting to the development of O. glumaepatula than it is in the natural area. The reduced values of biomass and density of O. glumaepatula in the impacted area suggest that the bauxite tailings limit the development of this population.

Temporal variations in the primary productivity of Eleocharis acutangula (Cyperaceae) in a tropical wetland environment

“…The biomass data obtained in the present study was similar to that reported in other studies: Santos & Esteves (2004) noted that the total biomass values of Eleocharis interstincta (Vahl) Roemer varied from 20 gDW m -2 to 339 gDW m -2 in the Jurubatiba coastal lagoon; Enrich-Prast et al (2002) reported that the total biomass values of Oryza glumaepatula Steud. varied from 7.1 gDW m -2 to 467 gDW m -2 in a non-impacted area of Lake Batata in the Amazon Region.…”

Flood pulse influence and anthropic impact on the chemical composition and energy content of Oryza glumaepatula in an Amazonian lake

“…On the other hand, the phosphorus concentrations presented a more conspicuous reduction from the low-water to the filling period in the impacted area. The same pattern was observed in a study on spatial variation in nutrient concentrations in stands of O. glumaepatula in the natural and impacted areas of Batata lake (Enrich-Prast et al, 2002). These results suggest that from the low-water to the filling period nitrogen becomes more limiting to O. glumaepatula in the impacted area, whereas phosphorus becomes more limiting in the natural area.…”

“…Between the two areas studied, the variation in C:P ratios did not show a clear pattern. However, the N:P ratio demonstrates that in the filling and highwater periods, phosphorus can be singled out as the more limiting element in the impacted area than it is in the natural area, a result also presented by Enrich-Prast et al (2002).…”