Development of migration models for macroinvertebrates in the Zwalm river basin as a tool in river assessment and restoration management.

Human activities have severely deteriorated the Flemish river systems, and many functions such as drinking water supply, fishing, etc. are threatened. Because the restoration of these river systems entails drastic social and economical consequences, the decisions should be taken with enough forethought. Ecosystem models could therefore act as interesting tools to support decision-making in river restoration management. In particular, models that can predict the habitat requirements of organisms are needed to ensure that the planned actions have the desired effects on the aquatic ecosystems. In general however, habitat suitability models, such as artificial neural networks (Dedecker et al., 2004a), fuzzy logic (Adriaenssens et al., 2004), etc. do not include spatial and temporal relationships. Migration dynamics of the predicted organisms and migration barriers along the river may indeed deliver important additional information on the effectiveness of the restoration plans. In this context, migration models for Gammarus pulex (Crustacea, Amphypoda), Baetis (Insecta, Ephemeroptera), Ephemera (Insecta, Ephemeroptera) and Limnephilidae (Insecta, Trichoptera) were developed. These organisms are valuable indicators in water quality assessment (De Pauw & Vannevel, 1991), and provide representative insights in the behaviour of aquatic macroinvertebrate communities and the water quality status of rivers. The development of these migration models was developed on the basis of electricity laws, seen the relation between electrical stream intensity and resistances provides a good basis for the modelling of the movement of macroinvertebrates in function of migration barriers.