Improving ecosystem resilience & reducing nutrient pollution in Lough Carra, one of Europe’s premier SAC marl lakes
Start Date: 06/09/2021
End Date: 04/09/2026
Total Budget: 4,977,097 €
EU Contribution: 2,962,640 €
Coordinating Beneficiary: Mayo County Council
Contact Person: Martin Keating
Lough Carra is a marl lake (i.e. one with high alkalinity) in the Lough Carra/Mask Complex Special Area of Conservation (SAC) in the west of Ireland. Since 1970, the Lough Carra catchment has been subjected to significant pressures, particularly from agricultural intensification, with 25% of the catchment converted from natural or semi-natural vegetation to improved grassland. This has resulted in the loss of some semi-natural dry grasslands and scrubland as well as limestone pavement habitats. Over the same period, there were also significant increases in cattle and sheep stocking density as well as fertiliser and slurry application. Commercial forestry has also increased and most houses in the catchment have septic tank systems for wastewater; some are old and likely losing nutrients to groundwater.
The aim of LIFE Lough Carra is to restore the marl lake habitat to favourable condition, improving its national status and trends. The project will also improve the conservation status of several other habitats and species: orchid-rich grasslands, limestone pavements, Cladium fens, common gulls, otters and lesser horseshoe bats. In addition, measures will be taken across the catchment to reduce losses of nutrients, by working with farmers and other stakeholders to change practices that are sources of pollution and biodiversity loss.
The specific objectives are to:
- Establish and promote a model of farming to transform nutrient management on farms in 10% of the catchment area during the project, for rollout catchment-wide afterwards, to protect and conserve 4 habitats (certain types of semi-natural dry grassland and scrubland, limestone pavement, hard water with benthic vegetation, and calcareous fen habitats);
- Define groundwater-surface water connectivity in the catchment through a groundwater study, to confirm the catchment boundary more exactly and help target nutrient-reduction actions;
- Demonstrate and adopt an integrated approach to restoring the lake’s habitats by collaboration of local authorities, other public bodies, farmers, anglers, other local stakeholders and the public – including long-term decision making, land management, community awareness and involvement. This includes management of forestry in the catchment for biodiversity by Coillte, and actions by Office of Public Works to sensitively manage public drainage channels;
- Reduce nutrient pollution from septic tanks/domestic wastewater by education and public awareness; establish demonstration areas of constructed wetland and associated workshops and information, to complement increased inspections being undertaken outside of LIFE funding;
- Implement a strategy to tackle invasive species, including preventing the introduction of zebra mussels and controlling numbers of mink and feral geese; and
- Maximise the project’s impact on enhancing the coherence of the Natura 2000 network, with actions complementary to conservation targets in other SACs. Lough Corrib SAC, which is downstream from Lough Carra, is designated for some of the same habitats (certain types of semi-natural dry grassland and scrubland, hard water with benthic vegetation, and limestone pavement habitats); nutrient-reduction measures in Lough Carra will reduce nutrient flow to the Corrib SAC. The Galway Bay Complex SAC is also hydrologically connected. The adjoining Moore Hall SAC and nearby Towerhill House SAC are designated for lesser horseshoe bats so actions for this species are designed to promote the conservation interests of this species in the broader region.
LIFE Lough Carra will contribute to the development and implementation of EU policy and legislation in the area of nature and biodiversity, including the biodiversity strategy to 2030andthe Birds and Habitats directives. Specifically, the project supports the further development, implementation and management of the Natura 2000 network set up under Article 3 of the Habitats Directive, in particular the application, development, testing and demonstration of integrated approaches for the implementation of the Prioritised Action Framework for Ireland (2021-2027) prepared on the basis of Article 8 of that directive. This involves the development of a results-based agri-environmental scheme that facilitates the protection and restoration of the targeted habitats and species. In addition, LIFE Lough Carra will contribute to the EU farm to fork strategy’s aim to reduce pesticide use and nutrient loss with a focus on measures to improve nutrient management and knowledge dissemination of best practice.
- Research on Lough Carra’s microbialites (rock-like underwater structures made up of microbes) has shown that significant changes can be detected within 1 year, in response to altered nutrient availability, and that these metrics are good overall indicators of the lake’s nutrient state. A 10% reduction in microbialite chlorophyll content is expected in Carra’s south basin by year 5 of the project;
- Water monitoring in inflowing streams is expected to show significant reduction in total phosphorus over 12 years which will be demonstrated in sub-catchments with multiple participating farms by Year 5
- Measurable changes in Carra’s emergent vegetation may not occur during the project due to internal nutrient loading from the sediment. Changes in charophytes (a group of green algae) in response to nutrient reduction are known from Lough Ennell, but measurable results may not be detected until the 10-12-year mark. However, the north and middle basin of Carra are less enriched than the south basin, and changes in charophyte communities may well be detected here by year 5 of the project;
- Chlorophyll in water (phytoplankton) is expected to respond quickly to nutrient reduction to a significantly reduced figure by the end of the project and even further after 10 years.
- Proxy indicators for nutrient reduction will be used in farm assessments, adapted from the ‘habitat health’ system in the Burren LIFE project. With this system, some changes in management (grazing pressure, poaching, etc.) are measurable within 1 year, and increased plant diversity in 2-3 years;
- No further loss of limestone pavement and some calcareous fen habitats on any participating farms;
- No loss and improved habitat quality for some types of semi-natural dry grassland and scrubland;
- Tailored management measures in Coillte BioForest plans applied to almost 19 ha of forest;
- Increase in the mean population count of lesser horseshoe bats in Moore Hall and Towerhill House SACs combined from 722 in 2020 to 751 during the project;
- Successful nesting attempts by gulls are expected to recover to 2015 levels (24 breeding pairs) during the project, with further subsequent increases, following the start of mink control in year 1;
- Feral year-round population of greylag geese removed by year 5; and
- Continued absence of the zebra mussel.