EPA - Ireland's Environment, An Integrated Assessment - 2020

Ireland’s Environment – An Integrated Assessment 2020 Topic Box 7.1 Monitoring the Aquatic Environment Information on the presence and condition of various algal, plant and animal communities is used to assess the ecological health of Ireland’s aquatic environment. Every year, hundreds of river sites and dozens of lakes are sampled by field biologists. At each river site the presence of macroinvertebrates, such as snails and worms and the larval stages of aquatic insects, that live in the river is assessed. The types and numbers of macroinvertebrates present tells us about the quality of the water. The presence of sensitive species or groups, such as stoneflies and mayflies, indicates that the river is unpolluted, whereas the presence of pollution-tolerant species, such as certain types of snails, leeches and worms, indicates that the river is polluted. In lakes the composition of aquatic plants and the depth to which they grow is used as a measure of ecological status; plants are found at greater depths in unpolluted lakes. Most of the large estuaries around the coast are also sampled on an annual basis, and here field biologists monitor the frequency of phytoplankton blooms and the occurrence of opportunistic green seaweed mats. The information collected in the field is subsequently used to assess the ecological status of these waters. An EPA river biologist examines a kick-sample (lower right) for the presence of different macroinvertebrate indicators (top right). Changes and Trends in Water Quality The latest assessment of water quality in Ireland (2013-2018) shows that there is a continuing decline in high status water bodies, which is the cleanest water category, and an increase in the number of water bodies in poor ecological health. Even more stark is the dramatic reduction in the number of our most pristine rivers, which has fallen from over 500 sites to only 20 sites in 30 years. The Water Framework Directive specifically prohibits declines in ecological status. Ireland’s latest assessment of water quality shows that, while just over two-thirds of water bodies (1825) had not changed status since the last assessment (2010-2015), 483 water bodies declined in status and 368 improved (Figure 7.4). This resulted in an overall net decline in 115 surface water bodies or 4.4 per cent. This was driven mostly by the 5.5 per cent net decline in river water bodies. The only surface water categories to display a net improvement in status were coastal waters (a net improvement in two coastal water bodies) and lakes (a net improvement in 12 lakes). Figure 7.4  Percentage change in ecological status of surface waters between the assessment periods 2010-2015 and 2013-2018 (Source: EPA) Declines Improvements Stable 13.6 68.4 18.0 164