A TYPOLOGICAL CLASSIFICATION OF

HEADWATER STREAMS IN IRELAND

Maria Callanan, Jan-Robert Baars and Mary Kelly-Quinn

ABSTRACT

This article addresses the lack of knowledge with regards to the macroinvertebrate communities ofIrish headwater streams. The main objective of this study was to describe the macroinvertebratecommunities of 74 headwater sites representing a range of geological and geographical settings withthe focus on reference systems and to propose a typological classification of these sites. Four maingroups of headwaters were identified using multivariate clustering and ordination techniques todevelop groups and to determine the environmental factors associated with macroinvertebrateassemblages. The groups identified are largely grouped according to environmental variables. Group1 sites drained softer geology with non-peaty soils, with a higher conductivity and total hardness thanany other group. Group 2 had a similar geology and again drained mainly non-peaty soils but hadlower conductivity levels than Group 1 and had the greatest representation of cobble/pebblesubstrate among the groupings. Group 3 sites drained mainly siliceous geology with peaty soils andwere characterized by predominately bedrock and boulder substrates. Finally, Group 4 sites drainedsiliceous geology with peaty soils and were located at the highest elevations and had the lowest pH.A Canonical correspondence analysis (CCA) was conducted to determine the relationships betweenthe macroinvertebrate communities and the physico-chemical variables. It was clear that geology andits co-variables, including conductivity and pH, played a considerable role in defining the groups. Aone-way ANOVA also highlighted the significance of some of these variables in the grouping ofthese sites. This study highlights the importance of defining headwater typologies so that referenceconditions for each type can be established and thus form a baseline against which future changes inbiodiversity or water quality can be measured.

INTRODUCTION

Ecological heterogeneity within and among rivers,headwaters being no exception, poses a challengefor the assessment of anthropogenic impacts. Thewater framework directive (WFD) requirement toselect type-specific reference sites does to someextent control for this and so ecological status ismeasured in terms of the deviation from referencestate. Although headwaters do not fall within themonitoring requirement of the WFD, the RiverBasin District Management Plans must consider theeffects of diffuse anthropogenic inputs such asagriculture and forestry on headwater streams.This is important as the restoration of downstreamsites is unlikely without attention to headwaters andthe identification of these sources. Thus, theeffective assessment of the status of headwatersrequires some consideration of type-specific refer-ence conditions. The importance of headwaters andtheir conservation has been highlighted by severalstudies in recent years (Furse 2000; Callanan 2009;Heino et al. 2009; Clarke et al. 2010; Feeley andKelly-Quinn in press) which only compounds theneed for typological classification.

Various approaches have been adopted fortypological classification of rivers throughout theEU (Verdonschot and Nijboer 2004; Kelly-Quinnet al. 2005; Sandin and Verdonschot 2006; Turakand Koop 2008) but generally to the exclusion ofheadwaters. Two exceptions were noted, firstly, inthe UK where headwaters were included in theRiver Invertebrate Prediction and ClassificationSystem (RIVPACS) classification which is derivedfrom macroinvertebrate communities (Wright et al.1984; 1998) and secondly, Triest (2006) in Belgiumidentified three headwater groupings based onmacrophytes. However, the RIVPACS programmehighlighted the limitations of the models whenapplied to headwater streams as many unimpactedtest sites were classified as not ‘of good biologicalcondition’ (Furse 2000). This led to the develop-ment of a headwaters version of RIVPACS (Furse2000). Apart from the work of Furse (2000) andHeino et al. (2003a) few studies have defined typesspecifically for headwater streams. In Ireland, rivershave been assigned to 12 types based on thecomposition and abundance of the macroinverte-brate, macrophyte and phytobenthos communitiesof 50 potential reference river sites (Kelly-Quinnet al. 2005). Few if any of these sites may beconsidered true headwaters as the uppermost sites

Received 28 March2011. Accepted19 October 2011.Published 18 June2012.

Maria Callanan (Cor-responding author;e-mail: maria.callanan@ucd.ie); Jan-RobertBaars and MaryKelly-Quinn; Schoolof Biology and Envir-onmental Science,Science Centre West,Freshwater Biodiver-sity Ecology andFisheries ResearchGroup, UniversityCollege Dublin, Bel-field, Dublin, Ireland.

Cite as follows: MariaCallanan, Jan-RobertBaars and MaryKelly-Quinn 2012 Atypological classifica-tion of headwaterstreams in Ireland.Biology and Environ-ment: Proceedings ofthe Royal Irish Acad-emy 2012. DOI:10.3318/BIOE.2012.11.

DOI: 10.3318/BIOE.2012.11BIOLOGY AND ENVIRONMENT: PROCEEDINGS OF THE ROYAL IRISH ACADEMY, VOL. 112B, 243�255 (2012). # ROYAL IRISH ACADEMY 243