ABSTRACT1. Soft-water, oligotrophic isoetid lakes are vulnerable to eutrophication, acidification and alkalinization. As a result of these pressures a large proportion have undergone substantial deterioration in several European countries. The understanding of these systems has been limited by either a lack of lakes close to natural conditions or through receiving less focus in broader scale macrophyte surveys. This has resulted in a dearth of information on specific lake types in their natural condition. Sixty-eight soft-water lakes in Ireland were studied in order to achieve a better understanding of the biological and environmental conditions defining such lakes.2. Eight groups of lakes were identified using cluster analysis and indicator species analysis. Three groups were representative of isoetid-rich lakes displaying a high frequency of occurrence of Isoetes lacustris, Lobelia dortmanna or Eriocaulon aquaticum together with the almost ubiquitous Littorella uniflora. Canonical variates analysis indicated that alkalinity, total phosphorus (TP), catchment area, altitude, moors and heathlands, mean transect depth, colour and lake area were significant variables discriminating among the eight groups. Soft-water lakes with high amounts of isoetids tended to be less exposed, have broad shallow littoral zones with a high transparency and be situated in smaller catchments. Total phosphorus and alkalinity were typically low, although one group of isoetid-rich lakes had higher mean TP and alkalinity values. This group may contain lakes under threat from nutrient enrichment and alkalinization and also lakes that have higher TP and alkalinity naturally.3. Lakes with a prevalence of isoetids supported a greater diversity of macrophytes and chironomids indicating that such lakes may represent suitable conservation targets as they act as surrogates for soft-water lakes of high biodiversity. Other factors favouring a focus on isoetids in conservation strategies are their importance as a functional component in soft-water lakes and their sensitivity to lake and catchment environmental change.
the Environmental Protection agency (EPa) in Ireland is responsible for the ecological monitoring and assessment of 37 hydrometric areas covering 46 river catchments and over 13,000 km of river channel nationwide. The national river monitoring program commenced in 1971 and has developed further since 2007 into the National Rivers Water Framework Directive (WFD) Monitoring Program following the implementation of the WFD across the European Union. the monitoring program is designed to obtain sufficiently representative information to assess ecological quality for each water body assessed. Consequently, macroinvertebrate data have been collected at over 2,900 river survey stations on a minimum 3-year cycle to fulfil these requirements. While the EPA has collected these data for water quality assessments we recognize that the data have value beyond this one purpose. We provide a summary of how these 10,987 data records, covering the years 2007 to 2018, have been collected and used to deepen understanding of water quality, biodiversity and general ecological health of Ireland's river network.
The current national surface water monitoring programme in Ireland includes 224 lakes. Monitoring data from the period 2012Á14 are used to evaluate the performance of ecological assessment metrics in responding to eutrophication pressure, as indicated by average total phosphorus concentration (TP). For 70 surveillance lakes, the r 2 for relationships with TP was 0.65 for phytoplankton, 0.65 for macrophytes, 0.59 for phytobenthos and 0.32 for fish. Following normalisation of the Ecological Quality Ratios (EQR) to a 0Á1 scale; averaging together the results for phytobenthos, phytoplankton and macrophytes resulted in a higher r 2 of 0.84 with TP. Using the ecological boundaries intercalibrated across the EU, the corresponding TP concentrations for the high/good and good/ moderate boundary ranged from 8 to 11 and 16 to 30 mg l (1 respectively. Non-parametric multiplicative regression was used to examine the strength of influence of typological parameters on the relationship between the assessment metrics and TP. Typological factors found to be significant for these models included lake area, mean depth and alkalinity. However, the most important model parameter, as indicated by higher sensitivity values, was TP. This was in part because metrics were designed to detect eutrophication pressure, but also because typological factors are already considered in both metric application and through type-specific EQR boundaries (for example, through incorporating depth or alkalinity in typology). Marl lakes may represent a more sensitive lake subtype requiring derivation of separate, more appropriate environmental quality standards. Further analysis in this regard is required.
The current national surface water monitoring programme in Ireland includes 224 lakes. Monitoring data from the period 2012Á14 are used to evaluate the performance of ecological assessment metrics in responding to eutrophication pressure, as indicated by average total phosphorus concentration (TP). For 70 surveillance lakes, the r 2 for relationships with TP was 0.65 for phytoplankton, 0.65 for macrophytes, 0.59 for phytobenthos and 0.32 for fish. Following normalisation of the Ecological Quality Ratios (EQR) to a 0Á1 scale; averaging together the results for phytobenthos, phytoplankton and macrophytes resulted in a higher r 2 of 0.84 with TP. Using the ecological boundaries intercalibrated across the EU, the corresponding TP concentrations for the high/good and good/ moderate boundary ranged from 8 to 11 and 16 to 30 mg l (1 respectively. Non-parametric multiplicative regression was used to examine the strength of influence of typological parameters on the relationship between the assessment metrics and TP. Typological factors found to be significant for these models included lake area, mean depth and alkalinity. However, the most important model parameter, as indicated by higher sensitivity values, was TP. This was in part because metrics were designed to detect eutrophication pressure, but also because typological factors are already considered in both metric application and through type-specific EQR boundaries (for example, through incorporating depth or alkalinity in typology). Marl lakes may represent a more sensitive lake subtype requiring derivation of separate, more appropriate environmental quality standards. Further analysis in this regard is required.
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