Phytoplankton and Charophytes of Lough Bunny, Co. Clare

摘要: A year-long survey of Lough Bunny, a karst lake in County Clare, Ireland, was undertaken 1992-3. Water transparency (as determined by Secchi disc depth), plant nutrients, chlorophyll concentrations and phytoplankton were examined. High water indicated that the euphotic zone extended over majority may, at times, have reached deepest parts lake. Silicate-silicon nitrate + nitrite-nitrogen showed marked seasonal changes with lowest values recorded May 1992 August respectively. Molybdate reactive phosphate-phosphorus no seasonality concentration often below limit detection technique used. The maximum value obtained 3.9tg P04-P dm3. Chlorophyll also low throughout year, ranging from 0.5pg dm -3 to 2.6gg -3, these pattern change. Cryptophyta present all samples most numerous group phytoplankton. Small dinoflagellates occurred Ceratium species appearing summer months. Cyanobacteria common abundant late autumn. Dinobryon found year but mostly as single thecate cells only occasionally large arbuscular colonies. Diatoms not well represented plankton. Chlorophyta greatest diversity never abundant. Quantitative counts cell numbers groups be low, which is reflected concentrations. On this evidence it suggested oligotrophic. comparison two published lists lake's plankton made. There are extensive beds Charophyta list given. We suggest utihisation nutrients charophytes benthic diatoms may responsible for clarity small populations. C. Pybus (corresponding author; email: colin.pybus@gmit.ie)