%0 Journal Article
%T Interannual variability of phytoplankton in the main rivers of the Upper Paran¨¢ River floodplain, Brazil: influence of upstream reservoirs
%A Rodrigues
%A LC.
%A Train
%A S.
%A Bovo-Scomparin
%A VM.
%A Jati
%A S.
%A Borsalli
%A CCJ.
%A Marengoni
%A E.
%J Brazilian Journal of Biology
%D 2009
%I Scientific Electronic Library Online
%R 10.1590/S1519-69842009000300006
%X the interannual variation of phytoplankton communities in the three main rivers of the upper paran¨¢ river floodplain is evaluated in relation to changes in the hydrosedimentological regime. these changes are a result of climatic variability and the formation of porto primavera reservoir, located at the upper paran¨¢ river. phytoplankton species richness and density were investigated in rivers during a prior period (1993-1994) and eight years after reservoir impoundment (2000-2007). multiple analyses were conducted to test the differences between these time periods in order to find predictor variables for phytoplankton attributes. a total of 454 phytoplanktonic taxa were found. the regression analysis revealed significant differences between periods. in the years following construction of the porto primavera dam, species richness was lower in the paran¨¢ river and density was higher in the three rivers. in general, the algal density decreased from 2005 to 2007. diatoms and cyanobacteria contributed significantly to the total density during the period from march 1993 to february 1994. the years 2000-2007 presented the lowest diatom contribution to species richness and the highest cyanobacteria contribution. from 2000 on, cryptomonads and cyanobacteria dominated. the interannual variability of phytoplankton was probably influenced by changes in hydrosedimentological regime due to climatic variations (la ni£¿a and el ni£¿o - southern oscillation events - enso) and the operational procedures associated with an upstream reservoirs. studies on climatic variability and its effects on hydrosedimentological regimes of the paran¨¢, ba¨ªa and ivinhema rivers and the biota therein are necessary to obtain subsidies for management, including decisions related to the operation of dams upstream and downstream of the study area, with the purpose of minimizing risks to the environmental protection area.
%K potamoplankton
%K interannual variability
%K species richness and density
%K regulated rivers
%K upper paran¨¢ river floodplain.
%U http://www.scielo.br/scielo.php?script=sci_abstract&pid=S1519-69842009000300006&lng=en&nrm=iso&tlng=en