Distribution différentielle des Odonates et des Salmonidés indigènes et exogènes dans la réserve d’Orlu (Ariège, France)

Abstract

Differential distribution of Odonates and indigenous and exogenous salmonids in Orlu Protected Area (Ariège, France). — Species introduction may constitute an important threat to indigenous biodiversity. The naturalization of Brook Trout Salvelinus fontinalis in the Orlu Protected Area (Ariège, France) may affect local communities, especially Odonates. We surveyed the wetlands of this protected area in order to compare the distributions of Odonates and salmonids. Our results showed that the Brook Trout was absent in nearly all reproduction sites of Odonates. Brown Trout Salmo trutta fario was present in some of these sites. The sites where salmonids were present generally hosted few or no Odonates. Other sites were characterized by a relatively important typological and odonatological diversity, with specific assemblages that often showed an ecological and/or a heritage value. The spatial segregation was more conspicuous between Brook Trout and Odonates than between these latter and Brown Trout. Then, an eventual impact of Brook Trout on Odonates is plausible, but remains unconfirmed in our study in the absence of local data on the microhabitats occupied by both taxa.