Dr. Brendan O'Connor:

Lagoons are brackish or partly saline water bodies. They are classed as priority habitats under the habitats directive and must be protected by the State. Ireland has a total of 2,400 ha of this habitat with Lady’s Island Lake in Wexford at 300 ha being one of the largest.

Recent EPA surveys have shown that many lagoons, including Lady's Island Lake, are in bad ecological condition, as defined by the water framework directive. The CLEAR project proposed by Aquafact and Roden and Oliver Associates, and funded by the EPA, was designed to establish what had caused the significant deterioration in ecological quality when compared to the near pristine conditions in the 1970s. The project also included a survey of the nearby Ballyteige flooded sandpit, which was used as a control site. Surveys included monthly visits to the lagoon and the lake to collect water samples from ten locations in Lady's Island Lake, one site in Ballyteige and six streams that flow into Lady's Island Lake to establish levels of nutrients such as nitrogen, phosphorous, ammonium and chlorophyll a, which is a measure of algal biomass. The shallow and deeper waters of both locations were sampled to document the plants and animals present.

The results from the Lady's Island Lake surveys showed highly elevated levels of nutrients and chlorophyll a, with chlorophyll levels being six times greater than in Ballyteige. These highly elevated levels of chlorophyll a, or planktonic algal blooms, block sunlight from reaching the bed of the lagoon. As a result, the plants of the lagoon bed had died due to the lack of light. Decay of algal biomass resulted in de-oxygenation of the sediments and the death of the animals on the lagoon bed. A comparison with a survey of Lady's Island Lake in 1977 by Mr. Richard Bates proves the lagoon was once in near pristine condition but has now lost most of its characteristic biota. The reason for these changes lies in the excessive growth of algae and cyanobacteria caused by massive increases in inflowing nitrogen and phosphorus, estimated as 12 times greater than at Ballyteige, which is in good ecological condition as per the water framework directive.

The reason for these high levels are the high nitrogen and phosphorus concentrations in the inflowing streams feeding the lake. In turn, these levels can be related to intensive agriculture in the lake’s catchment. Poorly maintained septic tanks may also contribute. The problem is cumulative. Every year, more nutrient is added to the lake’s catchment. Some gets washed out to sea and some is released to the atmosphere but a large fraction accumulates in the lake sediments, which now have a sevenfold higher nutrient concentration compared to our control site.

Ireland imports hundreds of thousands of tonnes of fertiliser annually. Part is exported in food but the greater part is discharged into Irish ecosystems with extremely serious consequences, including loss of fisheries, destruction of wildlife heritage, pollution of drinking water and damage to tourism. In addition, the fertiliser lost to agriculture has to be replaced by importing yet more nitrogen and phosphorus thus aggravating the problem.

Lady's Island Lake exemplifies the problems involved in managing Irish lagoons. A number of problems must be solved on a national scale before habitat restoration is possible. These will require the following measures: reducing the use of imported fertilisers on farmland and research on the recycling of nutrients, increasing measures designed to retain nutrients on farmland such as buffer zones, wetland restoration or creation, or tree planting should be considered. Similar measures should be considered for commercial forestry and maintaining or restoring the salinity regime of Irish lagoons. Any restoration plan for Lady's Island Lake or any of the impacted Irish lagoons needs to be site specific. Restoration will be difficult and the efficacy of proposed plans should be tested on a demonstration site. Ultimately, the problem must be solved on a local scale with the involvement and support of local people. Burren Beo in County Clare, The Bride River project in counties Cork and Waterford or The Lough Carra Catchment Association in County Mayo have developed this approach with notable success.

Sin deirimid fé. Go raibh maith agaibh go léir.