This study is the eighth component of the ëResearch on the environmental effects of the SIGMA plan: Effects of dredgings and harbour expansion on the environmentí This study evaluates the developments in two mesocosm experiments: at Kruibeke, and on UIA-campus at Wilrijk. The mesocosm experiments at Kruibeke was created to estimate the impact of pollution on flooding areas. The structure at Wilrijk studies the influence of the tide on the increase of sheer. The flow of contaminants is monitored. The impact of pollution caused by the most important contaminants on key species (such as Oligochaeta and sheer) is quantified. The lethal responses are also quantified using biomarkers. A recent developed technique which shows shifts that are caused by pollution in microbial communities, is applied. Those microbial communities are responsible for important ecosystem functions such as the carbon and nutrient cycle.