title: Environmental response of an Irish estuary to changing land management practices.
abstract: Anthropogenic pressures have led to problems of nutrient over-enrichment and eutrophication in estuarine and coastal systems on a global scale. Recent improvements in farming practices, specifically a decrease in fertiliser application rates, have reduced nutrient loadings in Ireland. In line with national and European Directives, monitoring of Irish estuarine systems has been conducted for the last 30years, allowing a comparison of the effectiveness of measures undertaken to improve water quality and chemical and biological trends. The Blackwater Estuary, which drains a large agricultural catchment on the south coast of Ireland, has experienced a decrease in calculated nitrogen (N) (17%) and phosphorus (P) (20%) loads in the last decade. Monitored long-term river inputs reflect the reductions while estuarine P concentrations, chlorophyll and dissolved oxygen saturation show concurrent improvement. Consistently high N concentrations suggest a decoupling between N loads and estuarine responses. This highlights the complex interaction between N and P load reductions, and biochemical processes relating to remineralisation and primary production which can alter the effectiveness of the estuarine filter in reducing nutrient transport to the coastal zone. Effective management and reduction of both diffuse and point nutrient sources to surface waters require a consideration of the processes which may alter the effectiveness of measures in estuarine and coastal waters.
authors: Botany and Plant Science, School of Natural Sciences, Ryan Institute, National University of Ireland Galway, Galway, Ireland; Environmental Protection Agency, Richview, Clonskeagh, Dublin 14, Ireland. Electronic address: s.nilongphuirt@epa.ie.
authors: Sorcha
authors: S
authors: Ní Longphuirt
authors: Environmental Protection Agency, Richview, Clonskeagh, Dublin 14, Ireland.
authors: Shane
authors: S
authors: O'Boyle
authors: Botany and Plant Science, School of Natural Sciences, Ryan Institute, National University of Ireland Galway, Galway, Ireland.
authors: Dagmar Brigitte
authors: DB
authors: Stengel
mesh_terms: D000383:Agriculture; D002734:Chlorophyll / Q000032:analysis; D003247:Conservation of Natural Resources; D004784:Environmental Monitoring; D063366:Estuaries; D005068:Eutrophication; D007494:Ireland; D009584:Nitrogen / Q000032:analysis; D010758:Phosphorus / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D014874:Water Pollutants, Chemical; D002734:Chlorophyll; D010758:Phosphorus; D009584:Nitrogen
keywords: Agricultural policy measures; Estuarine eutrophication; Mann–Kendall trend analysis; Nitrogen and phosphorus river loads; Nutrient source apportionment