Utility of fluctuating asymmetry in caddisflies (Trichoptera) as an indicator of coastal wetland health in Lake Erie

Fluctuating asymmetry (FA) in caddisflies can serve as a tool to determine ecosystem stress. Eight Lake Erie coastal wetlands were sampled to determine if biotic differences between impacted and un-impacted wetlands could be detected. Adult caddisflies were sampled with modified UV light traps. Hydroptila waubesiana, Agraylea multipunctata, and Oecetis cinerascens were the most abundant trichopterans collected. We investigated whether levels of FA in the three species are correlated with wetland quality. We calculated diversity and richness of caddisflies for wetlands of differing quality in order to investigate how FA correlates with these measures. We assessed whether habitat generalist species, such as H. waubesiana, exhibit less symmetry than habitat specific species, such as A. multipunctata. Measurements of the FA on the length of three morphological characters were assessed, 1) front tibia, 2) front wing costal vein, and 3) antennal scape. In order to calculate FA, the absolute value of log right measurement minus log left measurement were taken for each character (FA=/logR-logL/). There was a significant increase of FA in the tibial length of H. waubesiana in impacted wetlands, implying that FA in H. waubesiana may be useful as an indicator in wetland quality. Neither character in A. multipunctata or O. cinerascens exhibited a significant difference in FA between unimpacted and impacted wetlands. There is no evidence that habitat specialists are more susceptible to asymmetry than habitat generalists. There was no significant difference in species richness, species diversity, species composition, and community structure between impacted and un-impacted wetlands.