Blue-green biodiversity: recognise, conserve, promote

The joint research initiative ‘Blue-Green Biodiversity’ (BGB) of the two institutes WSL and Eawag, funded by the ETH Board, has therefore been researching biodiversity at the interfaces of aquatic and terrestrial ecosystems since 2020. Today, Tuesday 3 September, the results will be presented to over 200 experts at the Special Info Day in Dübendorf. Here are three examples.

Wet, moist or alternately moist - blue and blue-green habitats are central to biodiversity in the city. As part of the BGB initiative, researchers have investigated what swims, crawls or grows along culverted streams and on newly created ponds or green roofs in the city of Zurich. They found a high diversity of species and were able to show that not only aquatic or semi-aquatic species, such as dragonflies or amphibians, but also birds, butterflies, grasshoppers and, above all, small invertebrates benefit from the enhanced habitats. ‘In addition,’ says WSL ecologist Marco Moretti, ’blue-green habitats and infrastructures have a key function for the distribution of many species. They form stepping stones and valuable corridors that strengthen resilient biodiversity.’ Environmental engineer Lauren Cook from Eawag goes even further: ‘In urban environments, well-designed blue-green infrastructure can fulfil many functions simultaneously - like a Swiss army knife,’ she says.

Biologist Sabine Fink (WSL) and environmental chemist Elisabeth Janssen (Eawag) have taken a close look at a special kind of blue-green biodiversity: Striking dark to black, often moist streaks on rock faces in the mountains, called Tintenstriche (“ink stripe”). The most important inhabitants of these communities are cyanobacteria, which are among the oldest life forms on earth. The bacteria, also known as blue-green algae, can photosynthesise and are therefore able to enrich the environment with oxygen. Genetic analyses of the Tintenstriche have revealed an as yet unknown diversity of cyanobacteria. The researchers are now taking a closer look. This is also because some of the gene segments identified enable the bacteria to produce substances that can be toxic to other organisms. So-called cyanotoxins have previously been known from lakes, where they can occur during cyanobacterial blooms and have already led to bathing bans or deaths in dogs. Can snails or caterpillars, which feed on the ink line mountain crusts, metabolise these substances? Or do they even store the toxins in their own bodies to protect themselves from being eaten? Blue-green systems still harbour some secrets - and research questions.