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UPDATE May 2019 to February 2020
Nutrient Input, Impacts and Processing.
Monthly nutrient water sampling is ongoing with sampling for May 2019 to February 2020 completed. Results have been received for all completed sampling. Five nutrient bioassay experiments have been completed with one final experiment remaining.
Lagoonal Ecology & Sediment Chemistry.
30 benthic faunal grab samples from 10 stations at Lady’s Island Lake and 6 from 2 stations at the control site at Ballyteigue were collected in September 2019. All faunal samples have been processed and sorted and the identification of the macrofauna is ongoing. Sediment samples for Particle Size Analysis and organics were taken at each of the benthic faunal stations.
Shoreline faunal samples have been taken at 8 shoreline stations and sorting and identification is under way. Shoreline sediment cores were collected at these stations and analysis of sediment chemistry is complete.
Monthly phytoplankton and zooplankton sampling is ongoing with sampling for May 2019 to February 2020 completed. Analysis of plankton samples has commenced.
A current meter was deployed on the 27th of June 2019 for three months; it was then redeployed on the 17th of October 2019 in a second location for a further 3 months. The meter has again been redeployed in February 2020 for a further 3 months.
Bathymetric and topographical data along with water level data has been received from Wexford County Council.
Construction of the hydrodynamic model will commence once current meter deployment is complete.
Dr. Cilian Roden and Dr. Geoff Oliver attended the EUROLAG conference in Venice in January 2020 to present a poster and paper on the project. The Abstract for the paper presented follows and the presentation slides can be viewed in Media tab:
CAN SHALLOW LAKE THEORY BE USED TO ESTABLISH ECOLOGICAL QUALITY INDICATORS FOR IRISH LAGOONS
Roden C.*, Oliver G., McCaffrey K., O''Connor B.
Galway Mayo Institute of Technology ~ Galway ~ Ireland, Aquafact International ~ Galway ~ Ireland
Many Irish lagoons are in poor condition, largely due to eutrophication. This opinion is based on a series of surveys undertaken since 1996 in order to implement both the Habitats and Water Framework Directives of the EU. While the total area of Irish lagoons is small (25 km2) there is a great range of environmental conditions including rock basin and sedimentary barrier morphologies, oligohaline to euhaline salinity, differing degrees of eutrophication and modified drainage. Salinity is the main factor determining species composition in invertebrate, angiosperm, algal or phytoplankton communities but other factors, especially eutrophication greatly influences community composition.
To date ecological quality has been estimated empirically. Here we apply the alternative lake state concept of Scheffer to the Irish data set (50 surveyed sites) to determine if lake state can be related to water chemistry and distinct plankton, phytobenthos and invertebrate communities. We also determine if the opportunistic algal state reported by De Witt and co-workers in French Mediterranean lagoons, occurs in Ireland.
Using values for factors such as total P, D.I.N.,Chlorophyll and euphotic depth associated with each ecological state (benthic/plankton/opportunistic algae), we propose boundaries to distinguish between favourable and unfavourable conservation status. We also define associated planktonic and phytobenthos communities and attempt to define associated invertebrate communities.
This work is an initial part of a 3 year project, financed by EPA Ireland, to plan the restoration of a 350 ha. lagoon in SE Ireland. By estimating N,P and Chlorophyll levels associated with phytobenthos dominance at other sites, target levels for nutrient reduction can be proposed and tested. Further work will relate nutrient and plankton concentration to nutrient inputs and recycling and conclude with estimates of land use change necessary to restore good conservation status.