ENERGY FLOW IN AQUATIC COMMUNITIES, EMPHASIZING LOTIC SYSTEMS

Abstract

A series of studies by Lindeman and Odum attracted scientific attention to the matter of biotic production and energy flow in aquatic ecosystems. Energy flow ecology fundamentally deals with how energy is transferred in a given system. The flow of energy generates a series of chemical reactions which may absorb or release heat, and these heat variations occur at the level of the individual, with subsequent effects over the entire population and ecosystem. Odum was the first author to develop a thermodynamic method to measure the state of maturity reached by a given system following biomass increment. This method was used to evaluate the individual performance of each of the ecosystem's parts based on the natural processes intrinsic to populations. Odum's theory can be further developed by including trophic web analysis, thus allowing assessment of the evolutionary stage of ecosystems based on emergent properties. The greatest obstacles for such an approach is the lack of quantitative data (biomass) that would include all organisms of any given ecosystem and the difficulty in finding useful tools to develop these studies. The objective of the present review is to present an historical account of the energy flow ecology in aquatic ecosystems, focusing on the main methodologies employed.