In the Paranapanema River mouth, Jurumirim Reservoir (23 degrees 27'-23 degrees 29'S and 48 degrees 39'-48 degrees 36'W, SP, Brazil), the biomass of E. polystachya was monthly determined with eight quadrats of 0.25 m2 from August 1993 to July 1994. The seasonal variation in biomass was unimodal, with greater biomass from November 1993 to April 1994. The average biomass was 1,933.7 +/- 479.5 gDW...