Did waterbirds gather in different water-quality areas along Belgium’s Lieve River?

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Freshwater ecosystems face increasing pressure from human activities, degrading water quality and changing habitats for aquatic species. Researchers investigated the relationship between water quality and waterbird distribution along the Lieve River in Belgium, using manual waterbird counts and water-quality data collected from 48 transects in March 2024.

Localized eutrophication was evident: total nitrogen (TN) was 2.7–5.6 mg L−1, total phosphorus (TP) reached 0.46 mg L−1, and median chlorophyll-a was 70 ppb, exceeding environmental thresholds. Prati index analysis classified 58.3% of sampling points along the river as “polluted,” reflecting extensive water-quality degradation.

Eurasian coots (71.4%) and wild ducks (72.4%) were predominantly found in polluted areas, thriving in nutrient-enriched habitats linked to high TP levels. In contrast, common moorhens (80.3%) favored areas of acceptable water quality, which the researchers interpreted as indicating higher water-quality requirements.

The researchers concluded that phosphate is a key driver of eutrophication, citing on-site TP concentrations far above environmental-standard thresholds. They called for research into advanced monitoring approaches to improve waterbird and water-quality assessments, conserve the Lieve River as one of Europe’s oldest artificial canals, and protect its waterbird habitats.