 |
This spring is located behind the local Roman Catholic Church in the village of St. Margarets in north Co. Dublin. Spring water is contained in a large rectangular well chamber approximately 6 m long by 3 m wide. A overflow pipe leads to a ditch which carries water at times of high spring discharge. The substratum appears to be semi-natural and consists of rocks, cobbles, pebbles, and some mud. Evidence indicates that this spring completely dries out each year, usually during the summer period (Minerex 1983) although anecdotal evidence also indicates that the spring well retained water throughout the year before approximately 1980 (Mary Murphy, pers. comm., 2003). Macroinvertebrate / faunal survey St. Bridget's well was sampled in spring but was subsequently found to be completely dry. A total of 485 organisms and 16 species or higher taxa were recorded from the only sample collected. The fauna was dominated by large numbers of the water louse Asellus aquaticus (>90% of the total organisms recorded). This sample was relatively species rich, with macroinvertebrates such as the beetle larvae Haliplus conformis, dipteran larvae Chironomous sp. and the freshwater mussels Sphaeridae indet. and Pisidium sp. The remaining fauna comprised mainly solitary specimens of other fauna including the Coleopterans Hygrobia hermani, Bagous sp., Nanophyes sp., Dryops sp., the Hemipterans Hydrometra stagnoma, and mosquito larvae Culicidae indet. Physico-chemistry On the only occasion when water was present at the surface here, water temperature was recorded as 10oC, pH 8.15, conductivity was 425 µS/cm, and oxygen concentration was 21.3 mg/l and 196 % saturation. Aquatic macrophyte survey Five species / taxa were recorded. All species were ranked as occasional. The plant community appeared undeveloped and comprised: the Bryophyte Fontinalis antipyretica and the following vascular plants: Apium nodiflorum, Elodea Canadensis, Polygonium amphibium and Ranunculus aquatilis.
|
© Ecological Consultancy Services Ltd 2003 |
