Lake acidity and metal contamination are environmental stresses that negatively affect many aquatic organisms in lakes in eastern Canada. Developmental stability, as indexed by fluctuating asymmetry (FA), is a putative cost-effective measure of environmental stress. In this study, we measured FA of the water strider Rheumatobates rileyi (L.) in lakes in the Sudbury area in relation to lake acidity (pH) and aluminum concentration. We did this to test the prediction that water striders inhabiting degraded lakes (low pH or high Al concentration) would exhibit decreased developmental stability (increased FA) compared with water striders from circumneutral lakes. As predicted we found that Al concentration (corrected for pH) was positively related to the average FA of samples. Contrary to expectation we found that pH (corrected for Al concentration) was also positively related to FA; thus, for a given Al concentration, more acid lakes had more symmetrical water striders than expected. We discuss the importance of our findings in relation to the use of FA as an index of environmental stress, for both water striders and other organisms.
Spatial trends in community richness, diversity, and evenness across rocky intertidal environmental stress gradients in eastern Canada