AGENT-BASED SIMULATION OF ECOLOGICAL MODELS António Pereira Pedro Duarte CEMAS – UFP, University Fernando Pessoa Praça 9 de Abril, 349, 4249-004 Porto, Portugal E-mails: apereira@ufp.pt, pduarte@ufp.pt Luís Paulo Reis NIAD&R - LIACC Faculty of Engineering - University of Porto Rua Dr. Roberto Frias, s/n 4200-465 Porto, Portugal E-mail: lpreis@fe.up.pt KEYWORDS Ecological Modelling, Intelligent Agents, Simulation Models. ABSTRACT Coastal lagoons ecosystems are very complex to model and its global behaviour it’s hard to simulate. This com- plexity is even greater if the simulation model includes the intelligent entities like decision-makers involved in the system. Typical ecological simulations include only models of entities that have a very easy to predict behav- iour (using mathematical equations and/or simple logical rules). However, in real ecological systems, man is heavily involved and his decisions are not based on fixed mathematical equations or simples rules but con- trarily they are based on an in-depth analysis of the environment using his knowledge. This paper introduces an approach to intelligent ecological systems simulation using the agent-based approach. Intelligent entities are modelled as agents that have perception of their envi- ronment, reason using their knowledge and are able to change the simulated environment by using a given set of configurable actions. INTRODUCTION The management of coastal ecosystems is a very com- plex but essential part of any sustainable development strategy. Located between land and open sea, these ecosystems receive fresh water inputs, rich in organic and mineral nutrients derived from urban, agricultural and industrial effluents and domestic sewage, and are subject to strong anthropogenic pressures due to tourism and shellfish/fish farming. The interactions between coastal lagoons, land environment and sea boundaries reveal high physical, chemical and biological complexi- ties, making the management decisions difficult to take and the consequences of these decisions very hard to predict. In Portugal, several state institutions are responsible for managing coastal ecosystems: ICN (Nature Conserva- tion Institute), City Councils, Official Tourism Manager, the Navy and some more. When these ecosystems are integrated in a natural park, the Directorate of the Natu- ral Park is also involved. The huge number of possible combinations generated by the different management decision options, the opposite interests of some decision agents and stakeholders and the slowness of the decision process make it very diffi- cult to implement efficient management policies. The fragmented legal framing of the administration responsibilities enables an overlap of abilities between two or more entities, leaving simple questions like: “Is it advisable to enlarge an opened navigation channel (due to tourism pressure)?” without an immediate answer. A positive answer to the previous question raises another complex one: “What will be the future consequences and/or benefits?” The ecosystem physical and biogeochemical complexi- ties justify the construction of mathematical models to make predictions about their evolution. Generally, these models don’t take into account the influence of the man- agement decisions taken by the responsible entities. This paper introduces a possible helper to fulfil this gap: an agent-based simulation of ecological models. The archi- tecture for the simulation system described herein is based on the “intelligent agents” approach (Norvig and Russel 1995; Weiss 1999; Wooldridge 2002; Reis 2003). An agent may be defined as a self-contained software program, specialized in achieving a set of goals, by autonomously performing tasks on behalf of users or other agents. Agents are particularly useful in complex, inaccessible and dynamic environments as ecosystems or other biological systems. The study presented try to obtain answers to the ques- tion: “How to combine the use of mathematical models and Geographical Information System (GIS) with multi- ple decision makers, represented by different intelligent agents that collaborate with a Decision Support System (DSS), in the management of a coastal lagoon ecosystem (Ria Formosa, Algarve)?” The following sections describe the type of ecological modelling problems under analysis in this study with some examples, the Calibration Agent developed under this project to calibrate the generic ecological model used, the Agent-Based Simulation approach, its architec- ture and examples of the implemented agents and their interactions with the simulation. The paper concludes with some conclusions and pointers to future work. ECOLOGICAL MODELLING Ecological models are simplified views of nature used to solve scientific or management problems. These models Proceedings 5th Workshop on Agent-Based Simulation H. Coelho, B. Espinasse, eds. (c) SCS Europe BVBA, 2004 ISBN 3-936150-31-1 (book) / 3-936150-32-X (CD)