Before the Habitats Directive, only four lagoons were at all well known in Ireland (Lady’s Island Lake, Tacumshin Lake, Lough Murree, Furnace Lough) and very few biological studies had been published. Under the obligations of the Directive, the National Parks and Wildlife Service (NPWS) of the Irish Government commissioned a series of surveys of coastal lagoons in Ireland in order to compile an inventory of lagoons in the country for selection of representative examples for designation as, or within, SACs. Surveys were carried out in 1996 (Good 1996, Good and Butler 1998, Hatch 1996, Hatch and Healy 1998, Healy and Oliver 1998, Oliver and Healy 1998). These surveys were summarised by Healy et al. 1997a,b,c. Further surveys were carried out in 1998 (Healy 1999a,b; Oliver 1999, Roden 1999, Good 1999, Good and Butler 2000). An inventory of approximately 100 lagoons was compiled as a result of these surveys and 36 of the higher conservation value lagoons were sampled over a 1-4 day period, depending on the size of the lagoon. More lagoons were sampled from 2002-3 as part of a PhD study (Oliver 2005, Roden 2004).