A limnological study of four lakes near Rotorua

Summary

Four lakes (Okataina, Rotoehu, Ngapouri and Okaro), near Rotorua, New Zealand, were studied in 1960–66 and their physical features noted. The seasonal changes in water temperature and heat budgets throughout the depth of the lakes were followed through several cycles, and differences between lakes correlated with the altitude and size. The status of the lakes ranged from oligotrophic to eutrophic; changes in values for dissolved oxygen, both diurnal and seasonal, are interpreted in terms of their primary production. The partition of some dissolved substances during thermal stratification and immediately after overturn is described and the biological consquences are noted. The hypolimnetic oxygen deficit, however, was found to be correlated with primary production only when a depth factor was incorporated in the expression.

The data were compared with those from lakes in other parts of the world. The value of various published correlations with biological production is discussed; a possible explanation is put forward for the comparatively high heat budget of Lake Okataina.