Research shows many species are declining in the Wadden Sea, while only a few are thriving
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The weighted vote count as the percentage of each trend type in all ecosystem components together (top row) and separately (for the groups specified on the left axis) is weighted by the number of years with observations. Credit: University of Groningen/Carl von Ossietzky Universität Oldenburg
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The weighted vote count as the percentage of each trend type in all ecosystem components together (top row) and separately (for the groups specified on the left axis) is weighted by the number of years with observations. Credit: University of Groningen/Carl von Ossietzky Universität Oldenburg
In a unique collaboration between the University of Groningen and the Carl von Ossietzky Universität Oldenburg, researchers studied population trends across 3,058 populations of various species throughout the entire Wadden Sea.
In all, 24% of the population showed a significant decline in size, and this trend is occurring simultaneously across various groups. Only 14% of the population showed an increase in size. The findings were published in the journal Global Change Biology.
The 'losers' are mainly native species, often related to each other, while the 'winners' are various non-native species. At first glance, birds seem to be doing well, but a number of species have been declining significantly since the late 1990s.
Phytoplankton and plants are also strongly represented among the losers, as these are species at the base of the food web. But bivalves, marine worms, and some fish such as the Atlantic cod are also struggling.
Overview of monitoring stations and periods for each organism group. Points reflect individual stations for the respective group (color) within the radius of the concentric circle. The red outline indicates the official UNESCO World Heritage boundaries. Credit: University of Groningen/Carl von Ossietzky Universität Oldenburg
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Overview of monitoring stations and periods for each organism group. Points reflect individual stations for the respective group (color) within the radius of the concentric circle. The red outline indicates the official UNESCO World Heritage boundaries. Credit: University of Groningen/Carl von Ossietzky Universität Oldenburg
It is striking that the declines in the numbers of the losing species often occur simultaneously, which points to a common underlying cause.
"In follow-up research, we aim to investigate the specific causes of these dramatic changes," says Britas Klemens Eriksson, Professor of Marine Ecology at the University of Groningen. "In any case, it is a warning signal of potential local extinction."
More information:
Synthesis of population trends reveals seascape-wide reorganisation of biodiversity from microalgae to birds, Global Change Biology (2025).
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In the Wadden Sea, 24% of studied populations are declining, mainly affecting native species, while only 14% are increasing, often involving non-native species. Declines are observed across multiple groups, including phytoplankton, plants, bivalves, marine worms, and some fish, suggesting a common underlying cause and raising concerns about potential local extinctions.
This summary was automatically generated using LLM.