, Volume 328, Issue 1, pp 5774
First online:
Quantitative relationships of invertebrates to pH in Norwegian river systems
 Jorunn LarsenAffiliated withBotanical Institute, University of Bergen
 , H. J. B. BirkslAffiliated withEnvironmental Change Research Centre, Department of Geography, University College London
 , Gunnar G. RaddumAffiliated withZoological Institute, University of Bergen
 , Arne FjellheimAffiliated withZoological Institute, University of Bergen
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The invertebrate fauna has been surveyed for twenty one unlimed generally acidic river systems in Norway. The data consist of 180 samples and 127 invertebrate taxa and associated water chemistry data (pH, calcium, acid neutralizing capacity, total aluminium, and conductivity). Multivariate numerical methods are used to quantify the relationships between aquatic invertebrates and water chemistry. Detrended canonical correspondence analysis (DCCA) shows one dominant axis of variation with high correlations for pH and aluminium. DCCA axis 2 is significantly correlated with calcium. The predictive abilities of invertebrates to pH are explored by means of weighted averaging (WA) regression and calibration and weighted averaging partialleastsquares regression (WAPLS). The performance of the methods is reported in terms of the root mean square error of prediction (RMSEP) of (observed pHinferred pH). Bootstrapping and leaveoneout jackknifing are used as crossvalidation procedures. The predictive abilities of invertebrates are good (RMSEP_{boot} for WA = 0.309 pH units). Comparison of the invertebrates with diatom studies shows that invertebrates are as good predictors of modern pH as diatoms are. RMSEP_{jack} shows that WAPLS improves the predictive abilities. Indicator taxa for pH are found by Gaussian regression. Anisoptera, Agrypnia obsoleta, Leptophlebia marginata, Sialis lutaria, and Zygoptera have significant sigmoidal curves where abundances increase with decreasing pH. Cyrnus flavidus shows a significant unimodal response and has an estimated optimum in the acid part of the gradient. Isoperla spp. and Ostracoda show significant sigmoidal responses where abundances increase with increasing pH. Amphinemura borealis, Diura nanseni, Isoperla grammatica, I. obscura, and Siphonoperla burmeisteri show significant unimodal responses and have high pH optima. Many taxa do not have statistically significant unimodal or sigmoidal curves, but are found by WA to be characteristic of either high pH or low pH. These results suggest that a combined use of Gaussian regression and direct gradient analysis is needed to get a full overview of potential indicator taxa.
Key words
invertebrates gradient analysis canonical correspondence analysis weighted averaging weighted averaging partialleastsquares regression indicator taxa for pH Title
 Quantitative relationships of invertebrates to pH in Norwegian river systems
 Journal

Hydrobiologia
Volume 328, Issue 1 , pp 5774
 Cover Date
 199608
 DOI
 10.1007/BF00016900
 Print ISSN
 00188158
 Online ISSN
 15735117
 Publisher
 Kluwer Academic Publishers
 Additional Links
 Topics
 Keywords

 invertebrates
 gradient analysis
 canonical correspondence analysis
 weighted averaging
 weighted averaging partialleastsquares regression
 indicator taxa for pH
 Industry Sectors
 Authors

 Jorunn Larsen ^{(1)}
 H. J. B. Birksl ^{(2)}
 Gunnar G. Raddum ^{(3)}
 Arne Fjellheim ^{(3)}
 Author Affiliations

 1. Botanical Institute, University of Bergen, Allégaten 41, N5007, Bergen, Norway
 2. Environmental Change Research Centre, Department of Geography, University College London, WC1H OAP, London, U.K.
 3. Zoological Institute, University of Bergen, Allégaten 41, N5007, Bergen, Norway