Giani, A. A.. Universidade Federal de Minas Gerais, agiani@icb.ufmg.br
Pinto-Coelho, R. A.. Universidade Federal de Minas Gerais, rmpc@icb.ufmg.br

 
PHYTOPLANKTON AND ZOOPLANKTON CHANGES IN A TROPICAL RESERVOIR AS CONSEQUENCE OF EUTROFICATION PROCESS
 
During five years (1993-1997), a limnological study was carried out at Pampulha Reservoir, a shallow urban water body. The trophic conditions of the lake has increased during this time. Phosphorus concentration increased from 1994 to 1997. Low levels of dissolved oxygen were observed, specially in 1997. Hypolimnion was frequently anoxyc. Many algal species presented seasonal patterns. Because of changes in the trophic conditions, however, some species decreased in the reservoir. Other showed higher concentrations in 1997 than in 1993. Dinophyceae, practically disappeared from Pampulha Reservoir from 1996. Cryptophyceae strongly improved their population in 1996 and 1997. Zygnematophyceae were removed from the reservoir in 1996, only one species occurred in 1997. Many Chlorophyceae (Chlorococcales) increased in this period. Cyanobacteria showed very low densities in 1995 and very high in 1994 and 1996. Among zooplankton, Daphnia spp (D. laevis + D. gessneri) always showed seasonal pattern, with higher densities between July and October. In 1997 they completely disappeared from Pampulha Reservoir. Moina micrura did not present clear seasonality. In 1997, however, its population was higher than the years before. Shifts in phytoplankton and zooplankton communities have been observed in Pampulha Reservoir as a consequence of the rapid eutrophication in the last years. SS25 SS39 SS19 Oral
 
Day: Tuesday, Feb. 2
Time: 11:00 - 11:15am
Location: Sweeney Center
 
Code: SS19TU1100S