ASPT and DSFI satisfied this condition but the residual distribution of NTAXA was close to a normal distribution only after logarithmic transformation.
The values of ASPT and DSFI for small streams increased with stream size, reaching a maximum at about 30.
Like bottom substrate, higher flow velocity revealed higher natural quality for ASPT and DSFI.
The biological quality according to ASPT and DSFI was significantly influenced both by latitude and longitude (Table 3).
Season was not a determining factor for ASPT (Table 3).
On stony or gravelly bottom (riffles), no influence of the sampling method on ASPT was observed.
When the values of both ASPT and DSFI reached a maximum at about 30.
According to Timm (2003), the taxa richness of Ephemeroptera, Plecoptera and Trichopera (EPT), but not the ASPT or DSFI values, are significantly influenced by substrate and flow velocity in Estonian streams.
The lower values of ASPT and DSFI in the western part (Fig.
While in our study ASPT did not depend and NTAXA depended on the season (spring, summer, or autumn), independence of both these metrics of the season was reported for British streams (Clarke, 2000).
Although the Austrian index of saprobity, based on identification to the species level, is considered more accurate for Austrian conditions compared with ASPT, a significant correlation occurred between them (Strubauer & Moog, 2001).
proc GLM data=streams; class sm substrate vel season; model ASPT LNTAXA DSFI = substrate|vel sm(substrate*vel) lat|lat|long|long@2 LL|LL|LL season / e3 ss3 solution; output out=ResAndPreds r=rASPT rLNTAXA rDSFI p=pASPT pLNTAXA pDSFI; .