The lake ecosystem model 'Rostherne' allowed a theoretical insight into delayed causal relationships in aquatic ecosystems. Model simulations were used to demonstrate the possibility of influencing a species dominant at a later stage of ecological succession, by alleviating growth limitation of a different species, dominant at an earlier stage. Such delayed relationships are characteristic of various types of systems (including ecological), and can be illustrated by using a simple Stella model presented here. The stated indirect regulation rule for consecutive stages of ecological succession provides an important theoretical basis both for certain ecological manipulations and for the better understanding of various environmental relationships. It should, therefore, prove useful for theoretical analysis of system dynamics, studies of terrestrial and aquatic ecosystems, management of natural resources, Environmental Assessment and Auditing. (C) 2000 Elsevier Science B.V. All rights reserved.