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(78-01) The purifying capacity of the Dutch Delta: compensatory capacity of ecosystems after restoration measures. Vorenhout, Michel*,1, Bakker, Jan2, Van Straalen, Nico1, Eijsackers, Herman1, 1 Institute of Ecological Science, AMSTERDAM, The Netherlands2 Centre for Ecological and Evolutionary Studies, Haren, The Netherlands ABSTRACT- The Dutch delta has been altered many times. Recent plans feature the increase of natural influences in former embankments. Restoration of salinity gradients, realignment of dams, allowing larger tidal influence and change in management, will all have an influence on pollutants present. Negative effects on biota after restoration, but also the positive effect of decreased availability can occur. We have proposed a conceptual model (Vorenhout, et al. 2000) that describes the interrelationship between changes in management and the availability of pollutants. We use this model to study the compensatory capacity of ecosystems, mainly of salt marshes. The model consists of two parts: the description of main influences on the availability of substances, the capacity controlling parameters (CCPs such as pH, Eh, organic matter), and the factors that influence the CCPs. We measure the CCPs in the field at three restored salt marshes and in two mesocosm studies. Main results from the fieldwork will be presented. In the mesocosms we study the influence of restoration of a salinity gradient on the CCPs in sediment, and the influence of Spartina anglica on CCPs and the subsequent metal cycling in the mesocosm. S. anglica is shown to play a major role in the ability of an intertidal flat to accumulate heavy metals. The integrated approach in our research can be an aid in assessing the reduction of availability of pollutants.(Lit: Vorenhout, M. et al., 2000. "Assessment of the purifying function of ecosystems." Environmental Toxicology and Chemistry 19(9): 2161-2163.) Key words: salt-marsh, feedback mechanism, model, compensatory capacity |
