Effects of biomass changes in the supply-demand balance of energy in aquatic food webs

Due to the complex interactions between the community and its environment, understanding the behaviour of ecosystems is a difficult and laborious task. In this paper, we study several aspects of the ecosystem characterised by food webs and how their energy balance is affected by changes in biomass and the availability of resources required for self-maintenance. Ecosystem behaviour, as expressed through the energy flows between compartments, and the respiration flows and biomass of 124 trophic models are analysed. The metabolism of food webs is characterised by measuring respiration flows and scaling biomass to the 3/4 power. On the basis of this scaling, 16 food webs were selected to make a comparative analysis of the system dynamics, assuming that metabolism, relative to the size and independence of the environment, is the main source of change in the supply-demand balance of energy. The results demonstrate the importance of variation in the biomass of primary producers for the availability of resources in the system, which is related to bottom-up control, whereas a decrease in the supply of resources by top predators is associated with top-down control.