FRESHWATER NEWS
Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB)
Research for the future of our freshwaters – that is IGB’s guiding principle!
March 2023
Valuable freshwater biodiversity ~ Better habitats instead of fish stocking ~ Invasive species discovered in Lake Stechlin ~ A bottleneck in the decomposition of ammonium ~ Cold-tolerant blue-green algae ~ Soil sealing in rural areas ~ Peatland fires pose new risks ~ Consequences of war for the water sector in Ukraine ~ Research project on the River Oder disaster ~ High-performing schools of fish?
Hello!
Last week marked the?50th #WorldWildlifeDay . For the past half century, it has been a reminder that numerous animal, plant and fungal species are under serious threat, with little time left to take effective action. In Germany alone, thousands of species are already considered endangered. Globally, we could lose a million species over the next 80 years – many of them from our #freshwaters . Researchers from IGB and the U.S. Geological Survey (USGS) Climate Adaptation Science Centers have recently identified why we cannot do without freshwater #biodiversity – and it is not just a matter of edible fish and the recreational value of life-harbouring water bodies.?
Habitats
If we want to protect fish species and sustain stocks, it is advisable to adopt an #ecosystem -based #management approach that restores key ecological processes and habitats. Cooperating closely with angling clubs, a research team led by IGB and Humboldt-Universit?t zu Berlin (HU) has presented a ground-breaking study:?according to the study, fish clearly benefit from #restoration measures such as the creation of shallow water zones. In contrast, purely species-focused actions such as fish #stocking fail to produce sustainable positive effects. The study published in Science also shows that freshwater biodiversity conservation is most effective when user groups are involved in the process. After all, it is not just the species that benefit from the improvement of freshwaters, but also humans.
Invasive species
Sometimes species colonise areas where they do not originally belong. This is what happened in Lake #Stechlin , a protected area, where?IGB recorded the presence of swarms of the invasive bloody-red mysid (Hemimysis anomala) for the first time. This species, originating from the Ponto-Caspian region, is increasingly spreading to aquatic ecosystems of north-eastern Germany. This can occur through a variety of introduction pathways such as via waterways, water birds or water sports equipment. The extent of the distribution and the consequences for the lake’s ecosystem cannot yet be estimated, but are now being investigated by IGB.
Archaebacteria?
#Archaebacteria are evidently less adaptable. These small organisms live in the depths of lakes, where they?help to keep the water clean. Archaebacteria detoxify substances such as the nitrogen compound #ammonium , which is introduced into water bodies by fertilisers, for example, as well as being produced naturally by metabolic processes. In high concentrations, ammonium is toxic to aquatic life in high concentrations and contaminates drinking water sources. An international team led by the Leibniz-Institut DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH with IGB’s involvement has shown that?this detoxification is only sustained by an extremely small number of specific archaebacteria species, making the self-purification capacity of #lakes potentially vulnerable to environmental change.
Blue-green algae?
#Cyanobacteria (blue-green algae) are not very popular, the reason being that they can impair the quality of water bodies. Cyanobacteria are considered to be heat-loving, which is why problematic algal blooms are mainly observed and monitored in summer. Now, an international research network involving IGB has shattered this paradigm, demonstrating that?blue-green algae #blooms can also occur in colder temperatures – even under ice.?If they go undetected, e.g. because they occur in deep layers of water, there are also risks to drinking water production.?
Sealing of soils
However, water bodies are usually impaired due to non-biological causes – for example, as a result of soil #sealing . While this problem has already been recognised in urban areas, soil sealing in rural areas has so far been underestimated as a factor in #water quality degradation. According to a recent study by Senckenberg Nature Research and IGB,?20 per cent of newly sealed surfaces in Germany are located in rural areas, and are not taken into account in calculations of #nutrient fluxes into water bodies. As a result, the nutrient loads of water bodies are systematically underestimated.?
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Peatland fires
#Peatland fires are another risk factor for #water bodies and #groundwater . Unlike forests and pastures, peatlands do not burn fiercely, but smoulder. Such smouldering fires are known to release significant amounts of greenhouse gases into the atmosphere, because peatland soils store much more carbon than other soils. But they also store large amounts of nutrients. Researchers led by the Universit?t Rostock have shown, together with IGB, that?peatland fires result in a multitude of water pollutants being mobilised and leached?– particularly from agriculturally cultivated #fens .
War in Ukraine?
Freshwater resources and water #infrastructure in #Ukraine are acutely endangered. Scientists from IGB and Senckenberg Nature Research have documented?the destruction and the long-term consequences and risks for the population, the environment and global food security. Their study shows a wide range of damage, including #flooding of large areas due to dam breaches, #pollution from untreated wastewater spills, dumped ammunition, an increase in mine water levels, and a significant decline in the quantity and quality of water for drinking and agricultural purposes.
Environmental disaster on the River Oder
Another disaster may be over for the time being, but it has not yet been overcome:?the massive #fish and #mussel kill in the #River #Oder . This was the scene of blooms of the toxin-producing alga?Prymnesium parvum?last summer, caused by excessive salt loads, low water levels, and high temperatures. Now, as part of a project funded by the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMUV), IGB researchers are investigating the long-term ecological impact of the man-made disaster, and whether the river can recover. Recommendations derived from this project should help to increase the River Oder’s resilience in the long term and restore the river system.?
Shoals
Finally, returning to #swarms :?What do the brain and a school of #fish have in common??They are both capable of efficient collective information processing, although each unit within them only has access to local information. In the brain, it is the stimuli from 86 billion neurons that form the basis for information processing; in the shoal of fish, it is the decision of each individual on how to move and interact with its neighbours. There is a hypothesis according to which the best performance of the brain lies at the border between order and chaos, in the state of so-called #criticality . Researchers from the "Science of Intelligence” Cluster of Excellence at Humboldt-Universit?t zu Berlin , Technische Universit?t Berlin and IGB have been able to demonstrate this hypothesis on a large school of fish.?
We hope that our newsletter has also been an efficient way of passing on information. Having provided you with this overview, we say goodbye for now – until the next issue of FRESHWATER NEWS.
The IGB Team
The next issue of FRESHWATER NEWS will be published in May 2023.