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The Distribution of the White-Clawed Crayfish,<i>Austropotamobius pallipes</i>, in Ireland

2005; Royal Irish Academy; Volume: 105; Issue: 2 Linguagem: Inglês

10.3318/bioe.2005.105.2.65

2009-003X

Andréanne Demers, John Lucey, Martin McGarrigle, Julian Reynolds,

Fish biology, ecology, and behavior

Stocks of the freshwater crayfish in Ireland are thought to be some of the largest in Europe. To better protect this species, it is necessary to update data on the geographical distribution of Austropotamobius pallipes on the island. Records from surveys carried out by the Environmental Protection Agency (EPA) from 1990 to 2003 and from specific crayfish surveys (2000 to 2002) were compiled to generate a distribution map of A. pallipes in the Republic of Ireland. The map shows that A. pallipes is still widely distnrbuted throughout the Irish midlands. Water quality data (Q values) were also analysed to establish if crayfish were, in general, found only in good water quality. Crayfish were most often encountered in unpolluted conditions but were also found in slightly polluted and moderately polluted water. Some populations were even found at sites with very low water quality. The percentage occurrence of crayfish sites (17.6) is broadly similar to that recorded in a survey carried out between 1976 and 1985. An abundant stock of A. pallipes in Ireland would act as a safeguard for this endangered European species. Andreanne Demers and Julian D. Reynolds, Zoology Department, Trinity College Dublin; John Lucey (corresponding author; e-mail: j.lucey@epa.ie), Environmental Protection Agency, Butts Green, Kilkenny; Martin L. McGarrigle, Environmental Protection Agency, John Moore Road, Castlebar, Co. Mayo. Received 2 April 2004. Read 14 February 2005. Published 15 August 2005. INTRODUCTION Austropotamobius pallipes (Lereboullet) is the only freshwater crayfish species occurring in Ireland. It is widespread in the midlands in areas where the geology is predominantly limestone (Reynolds 1982; Lucey and McGamrgle 1987). It can inhabit lakes, canals and rivers. Lucey and McGarrigle (1987) gathered records of A. pallipes in Ireland between 1976 and 1985 and established that this species is found in most of the midland catchments. The origin of the white-clawed crayfish in Ireland is still under debate. Reynolds (1979) first suggested a Lusitanian onigin for this species in Ireland. Lucey (1999) suggested, based on literary sources, that man had introduced crayfish to the island from British stocks in the sixteenth century. Recent studies of mitochondrial DNA show that the lrish stock possesses a single haplotype and that this genetic configuration occurs in a few populations in France but not in Bnrtain (Grandjean and Souty-Grosset 2000; Gouin et al. 2003). Furthermore, a decline in genetic vanability was observed from south to north in Ireland, which would imply an initial introduction in the south and further colonisation of the island by this founder population (Gouin et al. 2003). Although its native status is in some doubt, the white-clawed crayfish is now considered a keystone species in Inrsh freshwater habitats (Matthews et al. 1993; Reynolds 1997) and is protected in the Republic of Ireland by the Wildlife Act (1976) and through the Wildlife anid Countryside Act (1981) in Northern Ireland. Recent surveys carried out in a few catchments showed that the distribution of A. pallipes is no longer what it was in the nid-1980s (Demers and Reynolds 2002; 2003). This change in distribution can be attributed in part to an outbreak of the crayfish plague caused by the fungus Aphanomyces astaci. This disease was introduced to Europe along with American crayfish species (Alderman 1996). Although alien species were not introduced to Ireland, the plague nevertheless made its way to Irish waters in the mid-1980s (Reynolds 1988; Matthews and Reynolds 1990). Crayfish populations in lakes and rivers of the Boyne and Inny catchments are thought to have been decimated by aphanomycosis (Reynolds 1988; Demers and Reynolds 2002; 2003). Large, unexplained mortalities of crayfish have occurred where no other aquatic species has been affected, for example in the Ollatrim River (Co. Tipperary) in September 1998 (M. Fitzsimons, pers. comm.), in the King's River (Co. Kilkenny) in June 1999 (P. Kilfeather, pers. comm.), in Lough Owel (Co. Westmeath) in BIOLOGY AND ENVILONMENT: PROCEEDINGS OF THE ROYAL IRISH ACADEMY, VOL. 105B, No. 2, 65-69 (2005). e ROYAL IRISH ACADEMY 65 This content downloaded from 157.55.39.87 on Sun, 10 Jul 2016 05:07:27 UTC All use subject to http://about.jstor.org/terms BIOLOGY AND ENVIRONMENT July 2003 (M. Fitzsimons, pers. comm.) and most recently in the River Nore (Co. Laois) in August 2004 (C. Murray, pers. comm.). The collapse of crayfish numbers has also been reported for some Nore tributanres, e.g. the Gully, Goul and Erkina (M. Kelly-Quinn, pers. conmm.). Pollution and habitat change are also thought to have affected several Inrsh crayfish populations (Demers and Reynolds 2003). The present range of this crayfish species in Europe has been greatly reduced, mosdly because of plague outbreaks, but also due to habitat degradation (e.g. Bemardo et al. 1997; Holdich and Rogers 1997; Alonso et al. 2000; Fiireder et al. 2002). The North American signal crayfish, Pacifastacus leniusculus, has been introduced to Britain for aquaculture purposes and has subsequently has escaped into the wild, where it has had a devastating effect on A. pallipes stocks (e.g. Holdich and Reeve 1991). There is a real threat that this alien crayfish species, which is a vector of crayfish plague, will reach Ireland. A. pallipes is listed in Annex 2 of the EU Habitats Directive (CEC 1992) and is protected to some extent in countries where it occurs. A European-wide project called CRAYNET was created to promote knowledge based management of crayfish populations. A prerequisite is up-to-date data on distnrbution. The non-correspondence between published Irish crayfish distnrbution records and findings of recent surveys showing decreasing populations in some Irish catchments highlighted the need for an updated distnrbution map of A. pallipes in Ireland. The white-clawed crayfish has traditionally been descnrbed as sensitive to pollution and considered as a potential bioindicator of water quality (e.g. Jay and Holdich 1981; Holdich and Reeve 1991; Reynolds et a!. 2002b). However, studies carred out in Ireland demonstrate the capacity of this species to live in moderately polluted water (Demers 2003; Demers and Reynolds 2003; Gallagher 2003). In the context of the CRAYNET project and with the help of the Environmental Protection Agency (EPA), it was decided to compile a more recent distribution of crayfish in Ireland. We also took the opportuIity to investigate the range of Q values (water quality values) in which this species was found. MATERIALS AND METHODS The data presented in this paper come from two sources. The larger data set, covering rivers and streams in the Republic of Ireland, was collected by the EPA dunrng the monitonrng of biological water quality carried out on a three-year cycle by the regional inspectorates based in Dublin, Kilkenny, and Castlebar. These records date from 1990 to 2003 and update those presented in Lucey and McGarrigle (1987). The surveys were undertaken between June and September, using a standard net with a mesh of 12 threads per centimetre. These surveys did not target crayfish specifically. The second set of data comes from surveys that specifically targeted crayfish. These surveys were carned out by A. Demers between 2000 and 2002 in eight catchments (the Liffey, Boyne, Inny, Little Brosna, Brosna, Multeen, Awbeg and Barrow catchments). Baited traps and hand nets were used to catch crayfish between July and October in each year, as described by Demers and Reynolds (2003). Almost all of these records are for crayfish in rivers. Only one record from a lake was included in the data set. This is from White Lough (Co. Westmeath), where crayfish were recently re introduced by the National Parks and Wildlife Service in collaboration with the Zoology Department of Tnrnity College Dublin (Reynolds et al. 2000). The distribution map was generated using DMAP for Windows (Distribution Map Program); positive sites between 1990 and 2003 were plotted on a 5km2 grid. The relationship between crayfish occurrence and water quality of sites was analysed using the results from the scheme of biological assessment (Q-value system) employed in national monitonrng programmes. RESULTS AND DISCUSSION CRAYFISH DISTRIBUTION Crayfish are still widely distnrbuted throughout the Inrsh midlands (Fig. 1). A. pallipes was found in most of the major catchments of the midlands, except for the Boyne catchment, where its distribution is greatly restricted compared to the 1987 distnrbutioin of Lucey and McGarrigle (Fig. 2). This is probably because of the occurrence of crayfish plague in this catchment in the 1980s (Matthews and Reynolds 1990; Demers and Reynolds 2002). Most crayfish populations occur in limestone areas. They also occur at sites that have less easily weathered rock types but are either influenced by limestone from upstream (e.g. part of the Barrow and Bonet) or by calcareous glacial till that covers the landscape (e.g. upper Liffey). The kick-sampling method used is rather haphazard in terms of its efficiency at catching crayfish. In the 1998-2000 surveys, for example,