COMPARATIVE LIMNOLOGY OF 4 CUBAN RESERVOIRS

Four Cuban reservoirs (Higuanojo, Tuinicu, Lebrije and Zaza) in the Sa ncti Spiritus province were studied in 1988-1989. The study was based on monthly samples of physical, chemical and biological components of the pelagic ecosystem. The reservoirs were warm-monomictic with more o r less complete water mixing during the dry season and stable stratifi cation during the wet season when inflow of water was highest. The mix ing event was very important in regulating the biology and chemistry o f the reservoirs. During the stratified period the water was anoxic be low 10 m depth and reduced compounds, especially ammonium, accumulated . In the reservoirs with less stable stratification, ammonium was occa sionally oxidized and the nitrogen lost to the atmosphere through deni trification. Phytoplankton biomass varied considerably among reservoir s and was not only correlated to total-P, but also to light, Zooplankt on biomass and composition was related to availability of good quality food and to the intensity of fish predation.