An environmental study of the west's six great lakes has recommended new approaches to monitoring water quality which may give a more accurate picture of their state.
Water quality in the six lakes is better than some previous reports had suggested. However, three have shown signs of eutrophication and enrichment (caused mainly by phosphate-rich pollutants), according to a three-year study led by Dr Kieran McCarthy of NUI Galway's department of zoology.
Research on Carrowmore, Conn, Cullin, Carra, Mask and Corrib by NUI Galway was undertaken in partnership with the Central Fisheries Board and Aquafact Ltd. Results have been published by the Environmental Protection Agency (EPA). They show that although localised signs of pollution were detected in all, and significant enrichment was recorded in Carrowmore, Conn and Cullin, the lakes of the Corrib catchment have escaped the more serious effects of eutrophication noted in most of Ireland's other large lakes.
The study highlights the loss of many unique elements in the ecosystems, such as Arctic char which are no longer in Conn and Corrib. The authors attribute this to the combined effects of environmental deterioration and the introduction of species not native to the lakes. The research team stresses the importance of conserving the plant and animal communities, and maintaining their ecological integrity, so the lakes can still be used for domestic water, angling and other recreation.
Significantly, it recommends new approaches to monitoring. Nutrient inputs to the lakes and the variations in chlorophyll levels and other water-quality parameters should be monitored more systematically, and attention should be paid to all adverse environmental changes, not simply nutrient enrichment.
The team advises against introducing new species into lakes, including transfers of coarse fish from other parts of Ireland. Dense coarse-fish populations can affect lake ecology, and it cites as an example the effect of roach on healthy char stocks in Lough Mask, the roach having found their way there from Lough Corrib.
Lough Mask has a special environment. It is home to such species as the blind white crustacean Niphargus kochianus hibernicus, which is more typical of subterranean waters and is not found on other Irish lake floors. Rare insects such as the non-biting midge Corynocera ambigua are also indigenous to Mask. Scientists believe they "invaded" its waters soon after the retreat of glacial ice sheets over 10,000 years ago.
Dr McCarthy and his team say the ecological integrity of the flora and fauna can provide an early-warning system on problems in lake water quality and can be a protection when used with systematic analyses of water chemistry and monitoring of nutrient inputs. Dr McCarthy recommends research of the unique elements of the flora and fauna, given their sensitivity to change.
Anglers are quick to take a holistic view of their local habitat, and Dr McCarthy pays tribute to the support shown by local anglers for the university's freshwater research programmes. "The long hours that anglers spend on or near the lakes, or their in-flowing streams and rivers, provides them with ideal opportunities to observe fish and wildlife habitat conditions," he says.
He believes this contribution could be extended to the work of the fisheries board and long-term EPA surveys. Anglers could provide systematic records of localised algal blooms, and other visible evidence of fish habitat degradation, he says, and can be effective guardians against the introduction of unwanted species.
Ireland's lakes are now home to an increasing variety of "alien species" such as North American crustaceans and Japanese fish parasites, Dr McCarthy says. Some of these may cause unexpected changes in the ecosystems - to the detriment of fisheries and, in the case of Shannon's zebra mussel "invaders", to water-quality parameters.
The report, Investigation of Eutrophication Processes in the Littoral Zones of Western Irish Lakes, was part-funded by the European Regional Development Fund, and the NUI Galway team has recently begun a new interdisciplinary study of Lough Corrib as part of a major programme linked to the university's new environmental-change institute.
Several departments are co-operating in the new study, which is supported by the Higher Education Authority.
