Differential environmental impacts on small and medium size rivers from center of São Paulo State, Brazil, and regional management perspectives

Abstract

AIM: This study aimed to evaluate, comparatively, the influence of distinct environmental impacts in the watershed on the rivers Capivara, Lavapés, Araquá and Pardo and the transference of effects downstream. METHODS: The limnological/water quality study was carried out in rainy (March/2007) and dry (September/2007) seasons, considering 17 sampling stations. RESULTS: Variables such as channel width and depth, water velocity and temperature increased towards the river's mouth; water transparency, velocity and dissolved oxygen were higher in the upstream regions. Light penetration was total at most sampling stations and pH was predominantly acid. The sampling stations impacted by pollution sources, Lavapés and Araquá Rivers, exhibited higher values of electric conductivity, suspended solids, total nitrogen, nitrate, nitrite, ammonium, total dissolved phosphorus, BOD, and thermotolerant coliforms. Higher values of electric conductivity, turbidity and suspended solids were observed in the rainy season, whereas higher chlorophyll concentrations occurred in the dry season. The Lavapés River exhibits the worst environmental condition, while Capivara River is under better state of conservation. This study shows that it is urgent the implementation of measures for preservation and restoration of these regional aquatic ecosystems. All studied rivers were influenced by seasonal variation, sewage discharges and by watershed use and occupation. The TSI is a good analysis tool. The studied rivers export organic matter and TN, TP and SS loads to Tietê and Paranapanema rivers. CONCLUSIONS: This study show the importance of river management and that the accelerated degradation of the river systems indicates the little progress of the Brazilian legislation in terms of preservation and good management practices and that the interface between science, law, management and conservation need to be improved.

Aquatic macroinvertebrate community and water quality in River Tambo, Arequipa region, Peru

“…All twelve stations in this study showed high conductivity values. Sediment ingress because of the lack of riverside vegetation at all stations could be an explanation for these high values (Reis-Oliveira et al, 2014;Ternus et al, 2011). According to Rodier (1998) and Meneses-Campo et al (2019), the River Tambo have high mineralization, since the conductivity is higher than 1 000 µS/cm and these values rise progressively downriver, such as on stations E9, E8, E7, and E6 in this study, located in the middle to low zone of the river.…”

How seasonality and anthropogenic impacts can modulate the structure of aquatic benthic invertebrate assemblages

“…The problems caused by urbanization on stream ecosystems are accentuated in developing regions located in the tropics by problems related to culture, infrastructure and governmental actions (Agostinho et al 2005, Yule et al 2015. Unfortunately, little attention has been given to the ecological effects of urbanization on tropical rivers and streams (Yule et al 2015); also, few studies had been carried out in Brazilian urban streams, whether analyzing only the water quality (Cunha et al 2011, Oliveira et al 2014 or the structure of the benthic fauna (Cortezzi et al 2009, Souto et al 2011. More studies of urban stream ecology are vital for a better understanding of the processes involved and for implementation of better management actions.…”

Excessive Eutrophication as a Chemical Barrier for Fish Fauna Dispersion: A Case Study in the Emblematic Tietê River (São Paulo, Brazil)

“…Despite their better water quality conditions, the volumes (tributary water flow) are probably insufficient to cause a significant positive effect on the Tietê River. However, this is not a reason to neglect the potential contribution of the small and middle-size tributaries widely distributed along the Tietê River basin [46,47]. This process is especially important for observation in the near future, due to the present trend of sanitation measures implementation (sewage treatments plants) all over São Paulo State, after decades without effective actions.…”