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Die Zahl großer Süßwassertiere wie Störe, Riesenwelse, Flussdelfine, Flusspferde, Krokodile oder große Schildkröten ist weltweit stark zurückgegangen, ebenso wie die Größe ihrer Verbreitungsgebiete. Die Ursachen für die Gefährdung dieser Megafauna sind weitgehend bekannt, die Folgen des Verlusts für die Ökosysteme dagegen kaum.

Fish are changing how they search for and consume prey in warmer waters, with models suggesting extinctions become more likely due to this behaviour change. This is the result of a new study led by researchers from the German Centre for Integrative Biodiversity Research (iDiv) and the Friedrich Schiller University Jena, with the participation of IGB, published in "Nature Climate Change".

The striped marlin is one of the largest and fastest predatory fish in the ocean. This  species forms groups when hunting schools of small fish, aided by its long, spear-like rostrum. A study by the Cluster of Excellence “Science of Intelligence“ (SCIoI) with Humboldt-Universität zu Berlin and IGB now explains how the fish might coordinate the rapid sequence of their attacks without injuring each other. The key to this, they suggest, is rapid colour changes - like a traffic light. Bright body stripes signalise: "Now it's my turn to hunt".

Native fish species in the upper Danube River Basin have been particularly sensitive to changes in flow regimes in the past, while higher temperatures will pose the greatest threat in the future. The threat assessment will remain at least as high in the future. However, it could probably be mitigated by reconnecting former floodplains and improving river connectivity. 

The EU Nature Restoration Law (NRL) awaits its formal adoption within the next weeks. Amongst other goals, the NRL aims to restore 25,000 km of free-flowing rivers by 2030. The NRL represents an important opportunity for the restoration and safeguarding of European rivers, its biodiversity and ecosystem services they provide to people. However, seven central challenges must be anticipated in its implementation, which may compromise its success. 

The Red List of freshwater fish and lampreys in Germany has been updated for the first time since 2009. It shows a clear negative trend over the last 14 years: 21 species have been classified threatened. This means that more than half of the native species are now considered threatened or already extinct. With 10 per cent of fish species extinct, Germany is well above the European average of 2.5 per cent.

IGB has received more than 200 young European sturgeons, considered extinct in Germany, from INRAE, the French partner institute. It's a Christmas present we're particularly pleased about.

Excessive artificial light in freshwater environments has far-reaching consequences for aquatic organisms and entire ecosystems. But what exactly happens to light underwater?