Author/Editor		Urbanič, Gorazd; Toman, Mihael J; Krušnik, Ciril
Title		Downstream changes in caddisfly fauna (Insecta, Trichoptera) in relation to environmental variables in the river Ščavnica (NE Slovenia): a multivariate approach using a canonical correspondence analysis (CCA)
Translated title		Spremembe favne mladoletnic (Insecta, Trichoptera) po toku reke Ščavnice v odvisnosti od okoljskih spremenljivk: multivariatna metoda z uporabo kanonične korespondenčne analize (CCA)
Type		članek
Source		Acta Biol Slov
Vol. and No.		Letnik 43, št. 4
Publication year		2000
Volume		str. 21-35
Language		eng
Abstract		Downstream distribution of caddistly in the River Ščavnica was analysed in order to assess the major environmental factors associated with the caddisfly distribution. Canonical Correspondence Analysis (CCA) was performed to investigate these changes. A total of 216 quantitative benthic samples were taken at five locations along the river between October 1998 and July 1999. Number of species and diversity were highest at the upstream part of the regulated part of the river and lowest, due to severe organic pollution, before the river outflow. The presence of the river reservoir in the regulated part altered species composition and reduced species diversity, but number of species was relatively high. According to CCA and absence of caddisfly at last sampling site the river was divided into five zones. The CCA showed that downstream changes in conductivity and morphology from the spring source had the greatest impact on the caddisfly composition at the upper sites. In contrast, downstream changes in temperature and oxygen saturation had the greatest impact on the caddisfly community at lower sites. Downstream changes in species composition were observed also within nine species of the family Hydropsychidae, which are the most impacted by temperature and oxygen saturation.
Summary		V reki Ščavnici smo analizirali spreminjanje sestave združbe mladoletnic po toku navzdol v povezavi z nekaterimi okoljskimi spremenljivkami. Uporabili smo metodo kanonične korespondenčne analize. Skupno 216 kvantitativnih bentičnih vzorcev smo vzeli na petih vzorčnih mestih vzdolž reke med oktobrom 1998 in julijem 1999. Število vrst in vrstna diverziteta sta bili najvišji v zgornjem delu reguliranega dela reke, najnižja pa zaradi močne organske obremenjenosti v izlivnem delu. Prisotnost zajezitve v reguliranem delu struge spremeni vrstno sestavo, vendar se število vrst ni bistveno spremenilo. Glede na rezultate, ki smo jih dobili z metodo CCA in ob dejstvu da na zadnjem vzorčnem mestu mladoletnic nismo ujeli smo reko Ščavnico razdelili v pet delov. Osnovne spremenljivke, ki ločujejo izvirno favno od favne ostalega dela reke so električna prevodnost in razlike v morfoloških značilnostih struge. V nasprotju s tem temperatura in nasičenost vode s kisikom vplivata na sestavo združbe na vzorčnih mestih 2-5. Spremembe po toku so bile opažene tudi v razporeditvi devetih vrst iz družine Hydropsychidae. Spremenljivk, ki najbolj vplivajo na njihovo razporeditev po toku sta temperatura in nasičenost vode s kisikom.
Descriptors		FRESH WATER INSECTS ECOSYSTEM TEMPERATURE HYDROGEN-ION CONCENTRATION