FRESHWATER NEWS
Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB)
Research for the future of our freshwaters – that is IGB’s guiding principle!
November | December 2024
The beaver, a controversial mammal ~ First sturgeon offspring for the Elbe River since 2015 ~ Advantages of high-speed group hunting ~ DNA metabarcoding for monitoring aquatic insects ~ Landscapes as water reservoirs ~ IGB researcher D?rthe Tetzlaff receives multiples awards ~ A new children’s book about the Danube ~ Art and science at Berlin Science Week 2024
Hi!
What do you think about beavers? Do you welcome the return of this once-extinct species or do you have negative feelings about this “troublemaker”? The activities of beavers in and along freshwater ecosystems have polarised people between agriculture and forestry on the one hand and nature conservation on the other. IGB researchers have investigated which groups have particularly positive or negative feelings towards this controversial animal and why. And they explain what role beavers can play in our ecosystems.
Species conservation: the European sturgeon
Less controversial, but still threatened with extinction, is another flagship species of our rivers: the European sturgeon. With the ambitious aim of establishing a self-sustaining sturgeon population in the Elbe river system, one hundred young fish of this rare species were released near Magdeburg in September in the presence of the German Environment Minister, Steffi Lemke. It was the first sturgeon offspring for the river since 2015. The stocking was only possible because the first offspring from a French broodstock population had finally reached spawning age. Despite this interim success, the challenges remain considerable: of the 20 returnees that have been documented in the Elbe system since 2020, more than two-thirds died from injuries or suffocated in the low-oxygen summer conditions below the Port of Hamburg – before they could even reproduce. The reintroduction programme is coordinated by IGB.
Group hunting
A similarly large but much faster fish is the focus of researchers in the Cluster of Excellence Science of Intelligence , in which Humboldt-Universit?t zu Berlin and IGB are involved: using the example of the striped marlin, they examine the advantages and mechanisms of group hunting. In terrestrial predators, there is evidence that capture success increases when groups of prey flee, because weaker group members may become isolated and defenceless. In a field study off the coast of Mexico, the research team has now demonstrated this effect underwater: the faster the prey school moves, the higher the capture rate of the striped marlin. And prey isolated from the swarm are caught by the non-attacking marlins – an advantage of group hunting for the predatory fish.
Fisheries management
One of the fastest freshwater predators is the pike. The Bodden landscape (brackish lagoons) around Rügen (Germany) is home to a particularly large number of fast-growing stocks of this species, much to the delight of anglers. However, for some years now, pike catches and sizes of pike in the catch have been declining. At the end of the four-and-a-half-year BODDENHECHT project, IGB made recommendations on how to deal with the situation. These recommendations are now being implemented: The state of Mecklenburg-Western Pomerania is issuing new fishing regulations for the Bodden to make stock management more sustainable. The new coastal fishing regulations include, for example, protection zones and winter resting areas where fishing is prohibited, as well as catch restrictions.
Insect monitoring
With more than 1 million described species worldwide, insects are by far the largest and most diverse taxonomic group in the animal kingdom. Given the high species diversity and the increasing demand for more comprehensive data, traditional microscopic approaches cannot keep pace with the number of samples to be analysed. DNA metabarcoding is a molecular analysis method that offers a promising solution for efficient insect monitoring. A new study, to which IGB researchers contributed, provides detailed guidelines for the large-scale application of this method, also suitable for aquatic insects, including cost and time estimates.
Water in the landscape
Extreme droughts pose serious challenges: researchers from IGB and Humboldt-Universit?t zu Berlin , led by Doerthe TETZLAFF , are therefore investigating the ecohydrological processes in landscapes. As the research team describes in an article in the journal Nature Water, a better understanding of water storage dynamics at medium scales, i.e. areas between 10 and 100 square kilometres, could help to better predict and ensure the availability of water resources, even in times of climate change. To this end, the researchers synthesised findings from several long-term studies and introduced the concept of ecohydrological resilience.
D?rthe Tetzlaff has been awarded the Rüdiger Kurt Bode Foundation’s Water Resources Award 2024 for her pioneering research on the interactions between climate, land use, water quality and the ecohydrological processes that control water dynamics in landscapes. She also received the Polubarinova-Kochina Hydrologic Sciences Mid-Career Award from the American Geophysical Union (AGU) and was named one of “Berlin’s Top 100 Minds in Science” by Tagesspiegel. We would like to congratulate her on these achievements!
A new children’s book about the Danube
IGB researcher Gabriela Costea is part of an international team developing concepts for better management of the Danube. The overall aim is to ensure that this large river system is not only preserved as a natural habitat, but also provides important ecosystem services for people – an increasingly important issue in the face of climate change. One of the tools the researcher uses to inform citizens living along the river is a new children’s book on environmental education in the Danube basin, published in several languages. The book “Lau lacht wieder” (Lau laughs again) translates scientific findings into a story for young readers: What creatures live in the Danube, what are the human pressures on the river, and what can be done to protect it? The book was created in close collaboration with a book illustrator and a Romanian children’s author.
Art and science
With an installation at the Museum of Natural History, performances, live experiments and a freshwater disco at Holzmarkt, we've had an exciting few days diving beneath the surfaces of the Oder and Spree rivers with the Berlin Science Week audiences. Missed it? Then mark your calendars for 11 and 12 January 2025 when we present the collaborative project Oder Hive by the artist collective FrauVonDa// at Villa Elisabeth (Berlin).
Incidentally, beavers do not hibernate, but their activity slows down considerably in winter. Read on to find out how frogs, newts, mussels, fish and even water fleas survive the cold season and why algae can “bloom” even in winter:
We hope that you too get through the coming weeks safely.
The IGB Team
The next issue of FRESHWATER NEWS will be published in January 2025.
Experimental Medicine , Faculty of Medicine, UBC, Vancouver | Medical Content Writing
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