The ecological dynamics of Barra Bonita reservoir: implications for its biodiversity/A dinamica ecologica da represa de Barra Bonita: as implicacoes na sua biodiversidade

• Published in: Brazilian journal of biology 2008-12, Vol.68 (5), p.1079
• Main Authors: Tundisi, J.G, Matsumura-Tundisi, T, Abe, D.S
• Format: Article
• Language: English
• ISSN: 1519-6984

Barra Bonita reservoir is located in the Tiete River Basin--Sao Paulo state--22° 29" to 22° 44" S and 48° 10° W and it is the first of a series of six large reservoirs in this river. Built up in 1963 with the aim to produce hydroelectricity this reservoir is utilized for several activities such as fish production, irrigation, navigation, tourism and recreation, besides hydroelectricity production. The seasonal cycle of events in this reservoir is driven by the hydrological features of the basin with consequences on the retention time and on the limnological functions of this artificial ecosystem. The reservoir is polymitic with short periods of stability. Hydrology of the basin, retention time of the reservoir and cold fronts have an impact in the vertical and horizontal structure of the system promoting rapid changes in the planktonic community and in the succession of species. Blooms of Microcystis sp. are common during periods of stability. Superimposed to the climatological and hydrological forcing functions the human activities in the watershed produce considerable impact such as the discharge of untreated wastewater, the high suspended material contributions and fertilizers from the sugar cane plantations. The fish fauna of the reservoir has been changed extent due to the introduction of exotic fish species that exploit the pelagic zone of the reservoir.