S. Ormerod, Bethan R. Lewis, Renata A. Kowalik, J. Murphy, J. Davy-Bowker
{"title":"Field testing the AWIC index for detecting acidification in British streams","authors":"S. Ormerod, Bethan R. Lewis, Renata A. Kowalik, J. Murphy, J. Davy-Bowker","doi":"10.1127/0003-9136/2006/0166-0099","DOIUrl":null,"url":null,"abstract":"Using data from 132 acid-sensitive streams in Wales and Scotland from two available data sets, we tested a recently proposed indicator system that uses aquatic invertebrates to detect acidification in British rivers, the Acid Water Indicator Community (AWIC). Although many sites held less than a quarter of AWIC scoring taxa, index values at sites in both data sets correlated significantly with acid-base variables including pH, calcium concentration, alkalinity and dissolved aluminium. Relationships with acid-base status during acid episodes were particularly strong in the more comprehensive test set. Strong correlations between the AWIC index and pH in a subset of sites from Scotland indicated potential for some extrapolation beyond the initial calibration regions of England and Wales. Despite considerable pH variability within AWIC classes, measured base-flow pH was within 0.5 pH units of values expected from invertebrates at over 55-70 % of test sites, and within 1 pH unit at 87-100 %. This compares favourably with direct pH measurement, where samples at fortnightly-monthly intervals are typically required to confidently estimate mean pH within 0.7-1.2 pH units. These data, drawn from a realistic application, illustrate the potential accuracy and integrating value of invertebrate bioassessment in acid-sensitive waters. Further developments should involve more specific identification and targeted calibration to i) improve discrimination between sensitive streams of contrasting acidity; ii) further improve the accuracy of pH determination based on invertebrates; iii) avoid the apparent over-estimation of pH in the lower AWIC classes; iv) clearly differentiate between acid-sensitive and acidified streams.","PeriodicalId":8118,"journal":{"name":"Archiv Fur Hydrobiologie","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"2006-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"16","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Archiv Fur Hydrobiologie","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1127/0003-9136/2006/0166-0099","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 16
Abstract
Using data from 132 acid-sensitive streams in Wales and Scotland from two available data sets, we tested a recently proposed indicator system that uses aquatic invertebrates to detect acidification in British rivers, the Acid Water Indicator Community (AWIC). Although many sites held less than a quarter of AWIC scoring taxa, index values at sites in both data sets correlated significantly with acid-base variables including pH, calcium concentration, alkalinity and dissolved aluminium. Relationships with acid-base status during acid episodes were particularly strong in the more comprehensive test set. Strong correlations between the AWIC index and pH in a subset of sites from Scotland indicated potential for some extrapolation beyond the initial calibration regions of England and Wales. Despite considerable pH variability within AWIC classes, measured base-flow pH was within 0.5 pH units of values expected from invertebrates at over 55-70 % of test sites, and within 1 pH unit at 87-100 %. This compares favourably with direct pH measurement, where samples at fortnightly-monthly intervals are typically required to confidently estimate mean pH within 0.7-1.2 pH units. These data, drawn from a realistic application, illustrate the potential accuracy and integrating value of invertebrate bioassessment in acid-sensitive waters. Further developments should involve more specific identification and targeted calibration to i) improve discrimination between sensitive streams of contrasting acidity; ii) further improve the accuracy of pH determination based on invertebrates; iii) avoid the apparent over-estimation of pH in the lower AWIC classes; iv) clearly differentiate between acid-sensitive and acidified streams.