STRIVE - Environmental Protection Agency

2 Methodology
Molecular Diversity and Dynamics of Toxigenic Blue-green Algae in Irish Lakes
2.1 Sampling Strategy Design for the
2009 Summer Survey
Database management tools in ArcGIS were used
to design a sampling strategy of water bodies based
on attributes of river catchments from the west and
northwest of Ireland.
2.1.1 Study Area, Target Population and Sample
Size
Sampling was carried out over a period of 15 weeks
during the summer of 2009 (26 May to 3 September)
extending in latitude from 52°20’ south to 55°10’ north,
with a surface area of ~40,000 km2 and a population
of ~1,230,000 (Fig. 2.1). The study area crossed over
three river basin districts (North-Western, Western and
Shannon) and was constituted of soils predominantly
composed of carboniferous limestone and blanket peats
in the central region and the western-northern areas,
10
respectively. Modifications in land cover in the region
for the period 2000–2006 have mostly been restricted
to changes to transitional woodland scrubs, coniferous
forests and some degree of discontinuous urban fabric
(EPA Ireland, 2008a). Interrogation of a GIS database
maintained by the EPA showed the study area to
contain 9,019 water bodies, accounting for ~75% of the
national amount. Some lakes within the study area are
subject to a range of human uses, in particular water
abstraction and recreational activities. Two major lakes,
Lough Corrib and Lough Ree, have been attributed the
status of Nutrient Sensitive waters under the WFD and
are listed in Ireland’s Urban Waste Water Treatment
Regulations (S.I. 254/2001). Only water bodies greater
than 5 ha surface area were considered for sampling,
which amounted to a total of 1,230 lakes. The sampling
effort was set to 50 lakes (~4% of population) across an
area containing 59 river catchments.
Figure 2.1. Maps of Ireland showing the delineation of the river catchments (a) and the water bodies contained
within the study area (b).