European River and Brook Lampreys Habitat Preferences at Different Geographical Scales

Habitat characteristics associated with lamprey ammocoetes (Lampetra fluviatilis, L. and Lampetra planeri, Block 1784) were investigated at three different spatial scales: regional (Portugal), catchment (two river basins with different hydromorphological characteristics) and microhabitat. The main objective of this study was to identify the environmental variables responsible for the distribution of the Lampetra genus species in Portugal. Data on the distribution of the species was collected during a 2 year period with electrofishing surveys. The information gathered during the identification of the habitat preferences at a regional level (GIS variables), was used to build a predictive Model (Boosted Regression Trees statistical analysis) and an associated probability distribution map of the species in Portuguese watersheds. On the catchment level the same analysis was applied but different variables measured in the field, and spatially sampled to characterize the stretch, were used. The microhabitat preferences level was aimed to precisely characterize the patchy distribution of ammocoete beds.  The information is discussed to be of use as a tool to prioritize rivers for conservation of this highly threatened lamprey species in the Southern limit of their distributional range.