Factors affecting Sciomyzidae (Diptera) across a transect at Skealoghan Turlough (Co. Mayo, Ireland)

Sciomyzid flies, which have potential as bio-indicators, were sampled by sweep-net surveys at a turlough in the west of Ireland. Turloughs are ephemeral wetlands (unique to Ireland), which flood from groundwater in winter and empty in the summer, during that time, they are frequently grazed. The weekly survey consisted of ten linear sweeps (5 m × 1 m) in each of six homogeneous and contiguous vegetation zones throughout the summer of 2004. The fauna was dominated by univoltine species with Ilione albiseta being particularly abundant, though species displaying a range of phenologies and life histories were also present. Species richness and total abundance were significantly higher in the two zones with the highest hydroperiods. Mantel tests showed that the species matrix was significantly co-structured with permanent features of the physical environment, but not with stochastic sampling variables related to weather conditions. Mantel correllograms displayed typical patterns of autocorrelation for hydroperiod, soil moisture and soil pH in each zone and vegetation height, vegetation length and Ellenberg moisture index (weighted for vegetation composition) in each sweep-path. No patterns of autocorrelation were evident for distance among zones, area of patch of vegetation zone sampled, area of the vegetation zone on the whole turlough, soil mass-loss-on-ignition and Ellenberg N and reaction indices. These results provide strong evidence for high microhabitat specificity in Sciomyzidae at this site and indicate a major influence of vegetation structure and hydrological regime on their ecology.