The Oxygen Deficit in Jurumirim Reservoir (Paranapanema River, São Paulo, Brazil)

Oxygen actual and relative deficits in Jurumirim Reservoir were computed from the temperature and dissolved oxygen profiles determined in a study from March 1988 to March 1989. The reservoir presented an isothermy from June to September and a thermal stratification from October to March. Thermocline was always located at the 1/3 deeper zone of the water column. Clinograde oxygen profiles were observed during the thermal stratification period. Water in the reservoir was always well oxygenated until 20m depth along the year. At the bottom (25m depth), O2content decreased significantly during the thermal stratification period. Thus, the deficits were higher at the bottom. Total oxygen actual and relative deficits for all the reservoir ranged from 0.03 to 0.72 mg • cm-2and from 0.013 to 0.032 mg • cm-2• day”1, respectively. Using other trophic status indices such as Secchi disk transparency and chlorophyll-a concentration as well as the oxygen deficits, Jurumirim Reservoir can be categorized in the oligotrophic class. © 1992, The Japanese Society of Limnology. All rights reserved.