Conservation of Protists: The Krauthügel Pond in Austria

Although constituting more than 100,000 described species, protists are virtually ignored within the arena of biodiversity conservation. One reason is the widespread belief that the majority of protists have cosmopolitan distributions, in contrast to the highly hetereogenous biogeography of the "mega-Metazoa". However, modern research reveals that about one third of the known protists have restricted distributions, which endorses their conservation, at least in special cases. Here, we report what probably ranks as the first successful conservation intervention focused directly on known protist diversity. It is justified by unique species, type localities, and landscape maintenance as evidence for legislation. The protected habitat comprises an ephemeral pond, which is now a "Natural Monument" for ciliated protozoa. This wetland occupies a natural depression on the Krauthügel ("cabbage hill") south of the fortress of Salzburg City. When filled, the claviform pond has a size of ~30 × 15 m and a depth rarely surpassing 30 cm. Water is present only for some days or weeks, depending on heavy and/or prolonged rain. The pond occupied an agricultural field where root and leafy vegetables were cultivated for possibly more than 200 years. In the 1960s, this area became a grassland utilized as an autumn pasture, but was abandoned in the 1990s. Repeated sampling between 1982 and 2012 recovered a total of at least 150 ciliate taxa, of which 121 were identified to species level. Eight species were new to science, and an additional 10 poorly known species were reinvestigated and neotypified with populations from the Krauthügel pond. Both endemism and type localities justify the argument that the "integrative approach" in biodiversity and conservation issues should include protists and micro-metazoans. We argue that Krauthügel holds a unique reference node for biodiversity inventories to obtain the baseline knowledge-which is the prerequisite to monitor ecosystem integrity-and detect and evaluate impacts of natural and anthropogenic disturbances.