Project Methods

A total of seven warm springs were surveyed during three distinct seasonal periods.  Five springs were located in Leinster (the Dublin/ Kildare / Meath area). Three of which (Louisa Bridge, Leixlip, St. Patrick’s Well, Morristown and St. Gorman’s Well, Enfield) had been investigated by Fahy in 1975. The other two (St. Bridget’s Well, St. Margarets, Dublin and St. Patrick’s Well, Celbridge) were selected to increase the geographical range of sample sites. The two Munster springs (Knocksouna Spring, Co. Limerick and Mallow Spa, Co. Cork) were also selected to increase the geographical range of sample sites.  At least one of the wells (St. Gorman’s) was thought to support tufa formation prior to this survey and as such is also of significant interest to the Geological Survey of Ireland. One cold spring at Louisa Bridge in Leixlip, was also sampled as a control site for reference.

Invertebrates were sampled from open water, the substratum and emergent, floating and submerged vegetation using a pond net (dimension 250 x 250mm, mesh size 1mm). The survey aimed to collect a representative sample of macroinvertebrate species for each site.

In previous sampling of the warm spring at Dysart, Co. Kildare a novel sampling method was employed (EcoServe, 2002, Unpublished report). Any midwater invertebrates present were sampled by means of a light trap suspended in the water column for a period of approximately 3 hours. The light trap was constructed of a light plastic mesh bag (approximately 5mm lattice) that was filled in turn with plastic mesh, thereby providing an artificial substratum for mid water animals. Waterproof light sticks were illuminated inside the trap to attract target animals.

A zooplankton net (mesh size 250µm was suspended below the light trap to collect any organisms that were not retained in the mesh of the trap. The trap was retrieved after 3 hours and any organisms present were collected and preserved for laboratory identification. Inititally it was thought that this method would be suitable for warm spring sites in the current survey. However on consideration of water depth and light in the wells of the current project (St Patricks Well Celbridge and St Patricks Well Morristown), net sweep methods were considered more suited to the sites and more likely to provide representative sampling of the aqatic habitats present.

The bank side and fringing emergent vegetation of each of the sites was examined. This involved walk over observations and determining approximate abundances of the species present. This data was recorded on basemaps for each of the sites. Plant communities were also photographed. All plant species present during each survey were recorded and assigned an abundance ranking using the traditional DAFOR scale (Dominant, Abundant, Frequent, Ocassional, Rare). Submerged plants species were sampled by hand and then returned to the laboratory for closer examination. Representative samples were dried and pressed to produce a catalogue of species recorded in the warm spring habitats.

The following physico-chemical data were recorded at each sampling site:

• Conductivity (µS/cm) – LF 330 / SET WTW handheld conductivity probe
• Water temperature (^oC) - LF 330 / SET WTW handheld conductivity probe and reference thermometer on pH probe
• Dissolved oxygen - (mg/l and % saturation) – Dryden Aquaculture ‘OxyGuard’ handheld oxygen probe
• pH – (pH units) – pH 315i WTW handheld pH probe

© Ecological Consultancy Services Ltd 2003