New paradigms in tropical limnology: the importance of the microbial food web

Abstract

Limnology has traditionally been a science of temperate regions. Long-term studies are not common in tropical regions despite the number of large tropical lakes that constitute a significant proportion of global freshwater resources. A number of comparative studies have shown that tropical lakes are different from temperate lakes in some fundamental ways. Constantly high temperature and radiation have strong consequences for stratification and biological processes. Previous studies suggested that higher primary production on a given nutrient base in tropical lakes is related to their higher decomposition rates. Moreover, lower efficiency in transforming primary production to higher trophic levels in tropical lakes also has been postulated as a difference. Data on the microbial processes in tropical lakes are scarce, but fail showing any significant difference in epilimnetic decomposition (bacterial) processes between temperate and tropical aquatic systems. The most significant differences found so far are in autotrophic and consumer community composition and body size, which constrain the upper compartments of the food web in a deterministic way. The reconciliation of ecological theory and observations yields a conceptual framework that illustrates likely structural variations in food webs along the latitudinal gradient. © 2012 Springer Science+Business Media B.V.