Relationships between life-history strategies of European freshwater fish species and their habitat preferences

1. Focusing on the current environmental characteristics, the 'habitat template' theory proposes that life-history strategies summarise how evolution has shaped species to cope with the temporal and spatial variability of their present environment. The hierarchical 'landscape filters' concept predicts that the distribution of species reflects their specific traits that allow them to pass through multiple habitat filters. Together, these theories showed the importance of identifying the functional relationships of species to selective habitat forces in order to predict the organisation and response of communities to the environment. 2. We test the relationships between life-history traits of European freshwater fish species' and their habitat preferences, to detect the strategies adopted by fish to cope with their current habitat. For this purpose, we use published data on species traits and habitat preferences (microhabitat hydraulics, temperature and oxygen level). We use multivariate analyses to classify fish species' strategies and test the relationships between strategies and habitat preferences. 3. We identified a continuum of life-history patterns between two extremes, with opportunistic and periodic species. Our study supports the idea that microhabitat hydraulics plays a more important role as a template for these species ecological strategies than temperature and oxygen level. Indeed, riffle habitats may select opportunistic species whereas weak relationships are found between species strategies and both their temperature and oxygen level preferences. In addition, the ratio between mortality and growth rate (dimensionless trait), reflecting a trade-off between growth and survival, varied among species according to the use of their hydraulic habitat, with species using deep habitats exhibiting the highest values. 4. These general relationships between hydraulics and traits may be of importance in community ecology to develop predictive models to understand how fish communities change with the hydraulic environment.