Natural springs are endangered ecotones that are very sensitive to anthropogenic impacts. They are isolated island-like habitats at the beginning of headwaters, which hampers colonisation. The relatively stable abiotic conditions - mainly thermal stability - in springs was for long seen as the reason for the restriction of species to springs and cold-stenothermy was the main argument for the exclusive occurrence of species in springs – for crenobiosis.
The general goal of our research is to understand the nature of crenobiosis. Are species really bound to springs due to their adaptation to stable abiotic conditions? Are species inhabiting springs isolated relicts of a formerly widely distributed cold-water adapted fauna? To answer these fundamental questions of spring ecology that are also important for conservation strategies we will look at individual species traits and phylogeographic aspects. Our proposal is divided into three parts processing the research questions with different methodological approaches:
1. Reaction of species described as spring specialists to changes in temperature under controlled laboratory conditions in flow channels: What are the effects of temperature increase and increased temperature variability on the fitness of individuals?
2. Isolation of individuals of spring species using molecular genetic analyses: how isolated are populations of different springs from each other a) in a historical biogeographical perspective linked with Pleistocene refugia and b) in a recent perspective linked with conservation aspects.
3. Isolation of spring taxa on metacommunity level along a longitudinal geographical gradient: Is the faunistic change along the gradient correlated with the geographic distance or are environmental parameters more important?
Our model organisms in part 1 and 2 will be species described as spring specialists in literature. We will choose an active disperser, namely Crunoecia irrorata, and a passively dispersing water mite, Partnunia steinmanni. In part 3 we will take Hydrachnidia and Trichoptera as model groups.
The combination of three methodological approaches and three dispersal modes will allow a rigorous disentangling of crenobiosis. It enables us to propose sustainable management strategies for natural springs that ensure both, the conservation of unique habitats for plants and animals as well as the maintenance of key ecosystem services for humans.