Complexity and emergent properties in aquatic ecosystems: predictability of ecosystem responses

Abstract

1. The paper explores the predictability of ecological conditions in aquatic systems and of their responses to catchment management schemes, in which the hydrological and material loads can be accurately and precisely quantified. Linkages between catchment hydrology and impacts on water quality are considered. 2. New approaches to modelling the complex biological behaviour of recipient systems are briefly reviewed. The case is made for simulating emergent outcomes based on the adaptive strategies and dynamic behaviours of species attempting to meet their material demands within the supportive capacities furnished by local environments. This 'bottomup' approach is justified by the fact that ecosystems are the sum of their smallest components; their behaviour is the aggregate of the activities of individuals. 3. A framework model template founded upon the emergent properties of highperforming organisms is developed within the context of exergy fluxes and their deployment and against axes representing the resource-carrying capacity versus the energy (photosynthetic and chemical) available to process it. 4. Some worked examples of simulated emergence in lakes are given, using the phytoplankton-community model, PROTECH, to demonstrate the acuity of predictions of the responses to quite subtle variations in biologically active solutes and suspensoids to simulated communities of the pelagic.

A stochastic model of epilithic algal succession and patch dynamics in streams

“…In such cases, any emergence results from an incomplete account of behavior at the lower levels, rather than behaviors that only are conceivable at higher levels (Allen and Starr 1982). The Reynolds and Elliott (2012) model of phytoplankton communities also was able to predict outcomes that emerged under different environmental templates. However, one could argue that the reductionist construction of hierarchical constraints in both Reynolds and Elliott (2012) and our model prohibits the detection of emergent properties that cannot be derived from lower‐scale processes.…”

Introduction to the special issue: ‘Achieving ecological outcomes’. Why is translational ecology so difficult?

“…Harris & Heathwaite (2012) discuss the inherent complexities of catchment and river interactions from a complex‐systems perspective and attempt to reframe some of our more usual assumptions to take greater account of the small‐scale connectivity in and the fractal properties of these partly self‐organised entities. Similarly, Reynolds & Elliott (2012) explore the predictability of ecosystems in receiving waters and their responses to catchment management actions. They suggest new approaches to modelling the emergent properties of aquatic ecosystems.…”