Dredge disposal at sea. Biological monitoring of dredged material in the Flemish coastal area (MILIEUBAGGER)

What is the impact of the dumping of dredged material on the marine benthos? Material that originates from dredging to maintain the maritime access routes and ports, is dumped into the sea (when not reusable for beach nourishment) at five designated sites (S1, S2, Zeebrugge Oost, Oostende and Nieuwpoort). This amounts to 12 million tonnes of dry matter that is yearly dumped. Through a continuous monitoring program, we investigate the possible influence of the dumping of dredged material on the benthic ecosystem in and around the five current dumping sites.

Quantitative and qualitative analyses on the sediment and benthos in and around the five current dumping sites are conducted biannually in comparison with some reference zones in order to detect changes or trends. The most commonly used parameters for this are (1) density (number of individuals per unit area), (2) diversity (based on the number of species and the contribution of each species to the total density), and (3) biomass (weight per unit area) of the macrobenthos, the epibenthos and the associated fish fauna. Variations in these three parameters in the short and long term, in relation to some environmental variables (e.g. sediment composition and temperature), are used as an indicator.

Both the dredging and the dumping of this dredged material are subject to licensing conditions, which are internationally agreed upon (e.g. through the OSPAR Convention) and translated into Belgian legislation. The results of the continuous monitoring study on the effects of dredge disposals are biannually reported to the Maritime Access Division of the Department of Mobility and Public Works. Additionally, the research at ILVO Fisheries is combined into a synthesis report every other year with the work of MUMM, the Maritime Access Division, and the Coastal Division of the Agency for Maritime and Coastal Services.

Funding provider(s)
Departement Mobiliteit en Openbare Werken, afd. Maritieme Toegang