Habitat preferences of the endangered diving beetle Graphoderus bilineatus: implications for conservation management.

Populations of the endangered diving beetle Graphoderus bilineatus are decreasing across Europe. Evidence‐based conservation of its local populations requires good knowledge of its habitat requirements, but data from different countries are often incomplete or contradictory.Graphoderus bilineatus was common until 1950s but then almost disappeared in the Czech Republic. Using data from a recent field survey in its core distributional area in the Czech Republic, we evaluate its habitat preferences at the habitat and microhabitat scale.We found that extensively managed fishponds can provide similarly suitable habitats for G. bilineatus as do more natural habitats including floodplain and sandpit pools, while the species is typically absent in intensively managed fishponds. All else being equal, the species is more likely found in larger water bodies surrounded by other wetlands and is more often absent at sites in agricultural landscape.We detected only weak preferences on the microhabitat scale. They suggested that G. bilineatus tends to occur in deeper water but closer to the shore and in microhabitats dominated by Glyceria or Typha. These microhabitat associations partly differ from those reported from other countries.Moreover, G. bilineatus was found at localities with higher species richness of large‐bodied aquatic beetles, both common and threatened, supporting the species status as an umbrella species for other aquatic macroinvertebrates.Our findings provide guidelines for conservation management of currently known localities and other potentially suitable sites, including the creation of new ones. Finally, our study reinforces the Annex II species status of G. bilineatus in the Habitats and Species Directive. [ABSTRACT FROM AUTHOR]