Due to water levels

Lake Constance forget-me-not endangered by water levels

The forget-me-not needs constant conditions - which it is currently not getting.

(Bild: APA/UMG UMWELTBUERO GRABHER)

Floods, waves and dry spells - all of these factors put the Voralrberg spring-flowering plant under considerable strain.  

The endangered Lake Constance forget-me-not, a plant that is practically only found on Lake Constance and a few smaller lakes, could become a victim of climate change. Increasingly frequent unusual water levels in Lake Constance are having a severe impact on the plant. While there was a maximum of 200,000 rosettes in spring 2007, after the summer floods of 2024 only a good hundredth of that number was counted. The low vegetation on the gravel in the water fluctuation area of the Mehrerau lakeshore near Bregenz does not look spectacular, but this beach grass is a unique plant community in Austria whose development has been monitored since 2003. It consists of plants that are specialized in locations that are sometimes under water in summer but dry out in winter when the water level is low. The Lake Constance forget-me-not is of particular interest.

If things continue like this, the Myosotis rehsteineri population could shrink to a small number.

Markus Grabher, UMG Umweltbüro Grabher

Unusual water levels as a danger
In the mid-1980s, due to deteriorating living conditions, there were only pitiful remnants of the azure to pink-flowered, rather short-lived pioneer plant. Protection efforts from 2002 onwards brought improvement, albeit with great fluctuations, but the current monitoring report by UMG Umweltbüro Grabher, financed by the research department of inatura Dornbirn, is now making people sit up and take notice: In recent years, it has become apparent that the water levels of Lake Constance, which deviate significantly from the long-term average, are a "threat factor that should not be underestimated" for the Lake Constance forget-me-not. While the population still comprised around 200,000 rosettes in spring 2007, only a tenth of the plants were still present in spring 2024 after a series of unusually high water levels from 2012 onwards.

A unique plant world can be found on the shores of Lake Constance in Bregenz.

(Bild: Wikipedia / Friedrich Böhringer)

Wonderfully pretty: "Myosotis rehsteineri", the Lake Constance forget-me-not, is endangered and could disappear from the landscape.

(Bild: APA/UMG UMWELTBUERO GRABHER)

After the particularly long-lasting summer flood, only around 3,000 specimens were found in the fall of 2024. The timing of the flooding is particularly problematic: in 2024, the plants were already under water during the flowering period from April - they were unable to form seeds, hence the further "dramatic decline". If the water levels of Lake Constance normalize, a recovery would be possible because "Myosotis rehsteineri" can generally adapt quickly to changing conditions. "But if things continue like this, the population could shrink to a small number," warns expert Markus Grabher. Dry summers are good for the plant, but if there are too many, competing plants will take over the site. Another problem is strong waves caused by strong winds and bank erosion. In 2024, the Vorarlberg state government even had specially grown plants planted on the lakeshore near Lochau to safeguard the population.

More consideration for sensitive nature
The Mehrerau lakeshore and the mouth of the Bregenzerach have been protected since 1991. In June 2024, the alluvial fan of the Bregenzerach was integrated into the protected area, and access to the islands at the mouth of the Ach has been strictly prohibited ever since. However, the area is also a popular local recreation area. Because campfires, garbage and noise disturb the sensitive natural environment, the members of the nature reserve have to keep reminding visitors to be considerate and adapt their behavior accordingly.