An investigation of macrophyte and macroinvertebrate communities in lowland sites on the rivers of Milltown (Muckno Mill) lake catchment, Co. Monaghan, Ireland

摘要

The requirements of the Water Framework Directive (CEC 2000) have precipitated many national (Kelly-Quinn et al. 2005) and pan-European (Brabec & Szosz-kiewicz 2006) studies on the interactions between biological elements and physical and chemical water quality parameters. Kelly-Quinn et al. (2005) in a study with all sites of "high" ecological status, found that hardness and slope explained most of the variance in the 4 biological communities surveyed (macrophytes, macroinvertebrates, phytobenthos, fish). Ferreol et al. (2008) identified geographical position as a variable that influences macroinvertebrate species composition, as did Murphy & Davy-Bowker (2005) who also highlighted altitude. For macrophyte communities, Grasmuck et al. (1995) highlighted geology, while the STAR macrophyte project highlighted sampling period and shading (Brabec & Szoszkiewicz 2006). Macrophytes and macroinvertebrates are both used extensively to assess water quality, and when used together can provide a larger picture of water quality in a catchment (Caffrey 1987). Both communities, however, may be responding to different pressures (Kelly 1997). Both the macrophyte and macroinvertebrate water quality indices suggest that much of the Milltown Lake catchment is affected by eutrophication, but these indices disagree on which sites are most or least impacted (Wynne & Linnane 2007). In line with current research, our study employs appropriate multivariate statistics to explain variation in the sample communities. Because the study is restricted to one small catchment (34 km~2), variables such as hardness, altitude, geology, and geographical position will lack gradient when compared to the pan-European or national scales in those projects. Analyses were carried out to ascertain if the variance caused by water quality parameters associated with localised, anthropogenic factors could be more evident.