MONEOS ‐ geïntegreerd datarapport INBO: toestand Zeeschelde 2024: Monitoringsoverzicht en 1ste lijnsrapportage Geomorfologie, diversiteit Habitats en diversiteit Soorten

The latest report on the monitoring of the Scheldt estuary (MONEOS) highlights several developments. Most habitats in the lower Scheldt remain stable, while upstream the salt marshes are expanding and the total estuary area is growing due to nature expansion projects (Sigmaplan). A notable effect is salinization, which causes freshwater salt marshes to become more brackish. This results in fewer forests and freshwater plants, but more brackish reed vegetation.

In 2023, we observed a record number of benthic invertebrates (expressed in biomass) since the start of monitoring in 2008. This may be related to a recent decline in the number of shrimp and sturgeon shrimp. These species prey on benthic invertebrates, especially in the transition zone from saltwater to freshwater.

In 2024, we recorded the lowest number of fish species since 2009. Smelt are once again scarce, but there are record numbers of gobies, and we caught a new, non-native species: the Shimofuri goby. On a positive note, the long-term decline in overwintering waterbirds has been reversed. This clear increase is linked to the rise in the number of benthic invertebrates.

Finally, bank erosion is increasing, with intensification in the freshwater zone by 2025. Further research is needed here.