Illustrating catchment-reach coupling: the effect of discharge type on the distribution of larval fire salamanders
Waringer, Johann; Waringer, Andrea
The role of stream discharge regime in the distribution of larval fire salamanders was investigated in Lower Austria. To define the types of discharge we used the database provided by the Hydrographical Annual and for salamander distribution the "Atlas zur Verbreitung und Ökologie der Amphibien und Reptilien in Österreich" (Cabela et al. 2001), supplemented by our own observations. Based on 62 (sub-)catchments, Spearman's rank correlation coefficients (SRCs) between monthly Pardé coefficients and monthly larval records were low (< 0.32) and statistically not significant in all subtypes of winter-pluvial (wip) and pluvio-nival (pln) catchments, indicating that larval abundance and discharge were clearly out of phase. in nivo-pluvial (nip) catchments (srcs 0.67-0. 72; p > 0.05 - P < 0.001) and, even more so, in all subtypes of summer-pluvial (sop), winter-nival (win) and moderate-nival (gen) catchments (srcs > 0.86), P-levels and SRCs indicated a high degree of synchronization between monthly Pardé coefficients and monthly larval records. The percentage of catchments inhabited by salamanders was highest within WIP an. PLN discharge types, intermediate in NIP and virtually zero in WIN, GEN and SOP types. In PLN and WIP, the times of high discharge occur early in the year, and baseflow is reached again during larval abundance peaks. This pattern also ensures that temporary waterbodies have been re-filled by the preceding floods. In NIP catchments, high discharge and larval abundance peaks coincide, whereas in SOP catchments the discharge peak starts after the larval abundance has peaked.