Aquatic habitat modelling: biological validations of IFIM/Phabsim methodology and new perspectives

Cemagref, Quantitative Hydroecology Laboratory, 3 bis quai Chauveau, CP 220, 69336 F-Lyon

Abstract

Despite IFIM worldwide success, some criticisms have not been sufficiently addressed in the literature: lack of sufficient validation of the relationships between potential available habitat and biomass of fish, particularly in warmwater streams; complexity of habitat modelling; too narrow focus on selected fish species habitat instead of entire riverine ecosystem; complexity and expense of implementation. First, we briefly address the general context of ecological flows methods. Second, we present some successful validations of microhabitat applications at the fish population (Brown trout, Salmo trutta, L. 1758) and community levels. Finally, we present the results of the statistical analysis and modelling of about one hundred Phabsim simulations. The functions of habitat (WUA) versus discharge could be predicted by synthetic hydraulic variables, in particular the Froude and Reynolds numbers. A simplified alternative to Phabsim, named Estimhab opens the way to habitat measurements in a great number of sites, particularly useful to view habitat at entire watershed level.