Longitudinal processes in Salto Grande reservoir (Americana, SP, Brazil) and its influence in the formation of compartment system

Abstract

Studies on the longitudinal processes in reservoirs, involving physical, chemical and biological processes have been thoroughly appraised, suggesting the existence of a longitudinal organization controlled by the entrance and circulation of water which inserts modifications in the structuring of the system. To evaluate this effect, the Salto Grande reservoir (Americana, SP) was analyzed in 11 sampling stations in its longitudinal axis, in the rainy and dry seasons of 1997 considering the physical chemical and biological variables. Analyzing the results in agreement with the declining concentration degree of the river-barrage direction, a more significant correlation was verified in the dry period for total phosphorus (r2 = 0.86), dissolved total phosphate (r2 = 0.83), nitrite (r2 = 0.93), inorganic phosphate (r2 = 0.89), ammonium (r2 = 0.84) and suspended material (r2 = 0.85). In the rainy period, only nitrite (r2 = 0.90) and conductivity (r2 = 0.89) presented correlation with the distance of the dam, which demonstrates the effects of precipitation and the operational mechanism of the dam, as well as the distinction among the physical (sedimentation), chemical (oxidation) and biological (decomposition) processes in spatial heterogeneity of the system. These factors were decisive in the organization of these communities, with higher occurrence of rotifers and copepods in relation to cladocerans, the first ones being more abundant in the entrance of the Atibaia river, decreasing towards the dam direction, while copepods presented an inverse pattern. A distribution pattern similar to Copepoda was also verified for the Cladocera, evidencing a tendency to increase the density of organisms in the stations distant to the entrance of the Atibaia river, not being registered, however, a distribution gradient in the longitudinal axis, as observed for rotifers and copepods. In relation to the trophic degree a longitudinal gradient was also verified from eutrophic to oligotrophic depending on the location of the sampling station in relation to the longitudinal axis and period of analysis. The differences obtained, relating to the distribution of the environmental variables, demonstrate a characteristic pattern for reservoirs, with a longitudinal gradient in the sense river-barrage that inserts changes in the physical and chemical composition of the water, contributing to the differentiated establishing of biological communities.

Seasonal variation of limnological features and trophic state index of two oligotrophic reservoirs of southeast Brazil

“…Variation in the nutrient contents along the longitudinal gradient was already observed in several reservoirs, as in Segredo (Thomaz et al, 1997) and Salto Grande (Zanata and Espíndola, 2002). In the present study, similarity among the sampling sites of each reservoir was observed.…”

Temporal and Spatial Distributions of Rotifers in Xiangxi Bay of the Three Gorges Reservoir, China

“…followed a similar longitudinal gradient reaching highest www.revhydro.com densities in the transition zone and lower in the lacustrine zone (URABE and MURANO, 1986;URABE, 1989). Copepods, on the other hand, were more abundant in the lacustrine zone (ZANATA and ESPÍNDOLA, 2002). The longitudinal distribution of rotifers in Xiangxi Bay was similar with the research of ZANATA and ESPÍNDOLA (2002) and densities were the highest in the transition zone, followed by the lacustrine and then in the riverine zone.…”

“…The longitudinal distribution of rotifers in Xiangxi Bay was similar with the research of ZANATA and ESPÍNDOLA (2002) and densities were the highest in the transition zone, followed by the lacustrine and then in the riverine zone. Rotifer density was greater in the transition zone, which was often observed by other authors (SEDA and DEVETTER, 2000;ZANATA and ESPÍNDOLA, 2002). This may be due to the transition zone having a lower current velocity than the riverine zone and supporting autochthonous organisms instead of allochthonous ones.…”

Uma metodologia para extração de conhecimento em séries temporais por meio da identificação de motifs e da extração de características

“…Os reservatórios são ambientes artificias distintos dos ecossistemas aquáticos naturais, pois são diretamente dependentes de mecanismos operacionais implicando em alterações nas características físicas, químicas e biológicas desses ambientes. O fator operacional juntamente com o efeito de forças naturais e do ciclo hidrológico causam uma distribuicão heterogênea das características desse ambiente, sendo possível observar três zonas que se diferenciam enquanto as suas características (Zanata & Espíndola, 2002). Como mencionado, essas zonas são denominadas de fluvial, transição e lacustre.…”