Heterotrophic activity and bacterial growth in a tropical lake (Lake Xolotlán, Managua, Nicaragua)

Summary

[³H]–thymidine incorporation was consistently high in the 4 monthly sampling dates of the rainy season averaging 91 pmol · l⁻¹ · h⁻¹ at station 1 and 65 pmol · l⁻¹ · h⁻¹ at station 7. The bacterial production varied however almost three-fold in the 4 morning sampling dates at station 7 in October due to the influence of the wind on sediments. Thymidine incorporation varied by a factor of 3 during the 24 hour diurnal sampling.

Bacterial Production (thymidine incorporation converted to units of carbon) averaged ca. 840 Mg C · m⁻² · Day⁻¹ in Lake Xolotlan. In a Recent Evaluation of Temperate Lakes (Cole et al. 1988) the highest production reported was 580mgC · m⁻² · day⁻¹. This high areal production of Lake Xolotlán may be partly due to the polymictic character of the lake and other properties of tropical lakes in general, i.e. constant high temperature, efficient nutrient cycling, and also by high and constant organic loading from the city of Managua.