Patterns of Ephemeroptera taxa loss in Appalachian headwater streams (Kentucky,USA)

Mayflies (Insecta: Ephemeroptera) are common inhabitants of streams throughout the Appalachian Mountains. Headwater mayfly assemblages were evaluated with respect to regional landuse disturbances (coal mining and residential) in eastern Kentucky, USA. Estimates of mayfly taxa richness and relative abundance were compared at 92 sites represented by least-disturbed reference (REF; n = 44), residential only (RESID; n = 14), mixed residential and mining (MINED/RESID; n = 14), and mining only (MINED; n = 20) landuse categories. A total of 48 species from 27 genera and 9 families were identified; Ephemerella, Epeorus, Ameletus, Cinygmula, and Paraleptophlebia comprised the core 5 genera most frequently encountered at REF sites. These same genera (among others) were often reduced or extirpated from other landuse categories. Mean mayfly richness and relative abundance were significantly higher at REF sites compared to all other categories; MINED sites had significantly lower metric values compared to RESID and MINED/RESID sites. Relative mayfly abundance was most strongly correlated to specific conductance (r = 0.72) compared to total habitat score (r = 0.59), but relationships varied depending on landuse category. Non-metric multidimensional scaling (for mayfly taxa) and principal components analysis (for environmental variables) separated REF sites strongly from most other sites. The results indicate that expected mayfly communities are disappearing from streams where mining disturbance and residential development has occurred and because of the long-term impacts incurred by both landuses, recovery is uncertain.