Odonata and wetland quality in southern Alberta, Canada: a preliminary study

The relationship between odon. and wetland quality was investigated in Brooks, from May until Sept. 1999. Sixteen study sites were each visited 7 times to survey adult dragonflies and aquatic macroinvertebrates, record environmental parameters, collect water samples, record vegetative characteristics, and assess beef cattle grazing influences. 25 odonate spp. were recorded, of which Ischnura verticalis is new to Alberta. A significant negative correlation was detected between cattle presence (measured as percent stems grazed surrounding the wetland) and odon, species richness (p = 0.022; r2 = 0.322), teneral species richness (p = 0.018; r = 0.337), and the Shannon-Weiner diversity indices (p = 0.060; r2 = 0.230) of the study sites. In addition, vegetation species richness and odon. species richness show a positive correlation (p = 0.066; f2 = 0.221). A logistic regression establishes that the absence of Coenagrion angulatum, Enallagma ebrium and Aeshna interrupta is associated with high cattle impacts, or low vegetation species richness. This study outlines the effect that cattle can have on wetland odon. species diversity and recommends that measures are taken to protect wetlands, while offering an incentive and reasonable cost/benefit ratio to both rangeland and wetland mangers.