Biodiversity in the Wadden Sea: Alarming decline in original species!

Biodiversity in the Wadden Sea: Alarming decline in original species!

A current study by researchers at Universities of Oldenburg and Groningen was carried out, offers a comprehensive insight into the changes in biological diversity in the Wadden Sea. This work, published on July 30, 2025, represents the first holistic analysis of biodiversity in this unique ecosystem. The Wadden Sea stretches over 500 kilometers along the coasts of Denmark, Germany and the Netherlands and is considered one of the most species-rich and dynamic ecosystems in Europe.

The study shows that populations of fish, plant plankton and coastal plants such as seagrass have declined significantly in recent decades. In particular, Atlantic cod, flatfish and various mussel species are recording alarming declines. At the same time, newly introduced species such as the Pacific oyster and the American razor clam have increased in population, indicating profound ecological changes in the Wadden Sea. Science reports that the influence of climate change, invasive species and human activities contribute significantly to these changes.

Long-term trends and biodiversity

Around 25 years ago, the previously positive trend for some bird species was reversed. While previously the population sizes of these birds, which use the Wadden Sea as a resting place or breeding site, were increasing, data show a continuous decline since the early 2000s. These findings result from the analysis of over 3,000 time series on the population size of various Wadden Sea inhabitants.

The oldest data on these holdings dates back to 1900, with many records beginning in the 1970s and 1980s. Of concern is the synchrony of negative trends commonly observed in related species. This suggests that similar survival strategies are compromised during times of environmental change.

Consequences for nature conservation and management

The results of the study not only have scientific significance, but could also have practical consequences for nature conservation and management of the Wadden Sea. They open up new perspectives to improve strategies for protecting biodiversity. UOL highlights that specific causes for the observed changes should be the subject of further investigation.

Overall, the analysis highlights the urgency of addressing the challenges that exist for the marine habitats in the Wadden Sea. The study's holistic approach allows examining the relationships between biological changes and various environmental pressures, which could be crucial for future conservation strategies.