Limnology of cuban reservoirs III: Zaza / Limnología de los embalses cubanos III: Zaza

ABSTRACT

Studies of physical, chemical and biological variables of the pelagic community were performed during 1989 in Zaza, the largest freshwater reservoir in Cuba. The reservoir is warm-monomictic. The circulation period lasted from October to March and the water column stability was low, due to a large surface area and to a wind exposed location. Dissolved oxygen was usually below the saturation point, owing to a high load of organic matter. The low oxygen concentrations appear to have responsible for a low efficiency in the decomposition of organic matter and in denitrification. The inorganic fraction of nitrogen was always detectable in the upper circulating layer (0-12 m), whereas inorganic phosphorus was only detectable after June. Standing stock of phytoplankton was relatively low. Phytoplankton production was probably limited by light and phosphorus. Diatoms dominated during the mixing period and Cyanophyceae and Crytophyceae during stratification. For most part of the year biomass of Copepoda was higher than biomass of Cladocera and Rotatoria