Biodiversity of Phoxinus minnows

Minnows (Phoxinus spp.) are small schooling fish that inhabit cool, oxygen-rich running and standing waters. Because different minnow species are difficult to identify based on external morphology, it was long assumed that only one species, “Phoxinus phoxinus” – the Eurasian minnow – existed in Europe. However, genetic analyses have revealed a much greater diversity, with over 25 species across Eurasia. Minnows play a central role in the food web and are highly sensitive to environmental changes. Climate change, rising water temperatures, and non-native species are putting their populations under pressure. Recent studies in Austria have shown that four minnow species occur there. Analyses of museum material from the fish collection of the Natural History Museum Vienna demonstrated that three species (P. csikii, P. lumaireul, and P. marsilii) are native, while “P. Phoxinus” was introduced from Northern Europe.

However, too little data was available to sustainably protect minnows in Austria. Not only time and financial constraints posed challenges for scientists, but bureaucratic hurdles also complicated data collection; for example, each federal state requires a separate collection permit. Therefore, a Sparkling Science project was launched, whose sampling strategy relied strongly on citizen scientists to collect samples. Pupils, supported by scientists, recreational fishers and fishing associations holding the necessary permits, as well as field biologists, were involved. This sampling strategy proved highly successful: within approximately 2.5 years, the number of sampling sites increased from 20 to 80. In addition, a new species (P. cf. morella) was recorded for the first time in Austria. The results confirm a high biodiversity within the genus Phoxinus: five minnow species inhabit Austrian waters – three native, one introduced, and one of unclear origin. Furthermore, mixed populations were identified, indicating hybrid zones. To better understand whether these hybrid zones developed naturally or were caused by human activities, additional analyses of the entire genome were carried out. These analyses showed that the current distribution patterns are influenced by both historical changes in river systems and introductions by humans. The results were published in two scientific studies. The collected data provided a solid foundation for future measures in minnow conservation as well as general fish and aquatic ecosystem protection. At the same time, further research is needed, particularly due to data gaps in other native fish species. The comparison with museum collections proved indispensable for reconstructing long-term changes in biodiversity.

The project involved more than 800 pupils aged 6 to 18 from Tyrol, Upper Austria, Styria, and Vienna in the scientific process, allowing them to experience science firsthand. For them, as well as for participating fishers, the project provided clear added value: they deepened their knowledge of biodiversity, improved practical sampling skills, and gained direct insight into scientific working methods. For field biologists, the project highlighted that higher minnow biodiversity should be expected, which is often not clearly distinguishable in the field. The project also demonstrated that citizen scientists can successfully contribute to biodiversity research when clear instructions and accessible feedback mechanisms are in place. The structured combination of guided sampling, scientific analysis, and open communication furthermore serves as a model for other freshwater organisms such as fish, amphibians, or invertebrates. Overall, the project showed that public engagement and scientific expertise complement each other ideally in improving the understanding and protection of Austria’s biodiversity – and that citizen science can strengthen environmental awareness, a sense of responsibility, and societal participation in the long term.