Bas van Maren, Harm Jan Pierik, Petra Dankers & Charlotte Schmidt

Eems-estuarium, slibprobleem, vertroebeling, primaire productie, ecologie

In de afgelopen decennia is het ecologisch functioneren van het Eems-estuarium verslechterd door toegenomen hoeveelheden slib. Om effectieve maatregelen te kunnen voorbereiden is onderzoek gedaan naar het gedrag van slib en naar de oorzaken van de hoge troebelheid. In dit artikel bespreken we de oorzaken van het veranderende slibgehalte, de effecten op de ecologie en ten slotte mogelijke oplossingsrichtingen om verdere vertroebeling te verminderen en de negatieve ecologische effecten ervan
te reduceren.

Siltation of the Ems Estuary

Ems estuary, siltation, turbidity, primary production, ecology

In this article we discuss the causes behind high mud concentrations in the Ems estuary, situated on the Dutch-German border. In addition we reflect upon its impact on ecology and potential measures to reduce this impact. Over the last decades, sediment concentration in the inner, muddy parts of the Ems estuary has increased, but not in the mouth of the estuary. In the upstream tidal river this increase results from deepening. The increasing mud content in the estuary results from loss of natural sediment sinks and possibly the artificial deepening effects of the tidal river. Observations suggest that the pelagic primary production has decreased in the outer estuary. However, primary production here is not light-limited and seems to be more strongly influenced by a reduction in nutrient availability rather than by changes in the suspended sediment concentration. The middle reaches of the estuary experienced an increase in mud content in the bed and saw a change in benthic fauna species composition, but to what extent these correlate cannot be established. The Dollard area has always been muddy and changes here are minor, but still experienced a decline in biomass. Measures aiming to reduce the suspended sediment concentration focus on reducing f lood dominance of the tide in the tidal river and on extracting sediment from the estuary.

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