Burgess, A; Goldsmith, B; Hatton-Ellis, TW; (2006) Site Condition Assessments of Welsh SAC and SSSI Standing Water Features. (CCW Contract Science Report 705 ). The Countryside Council for Wales

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Abstract

This report was commissioned by the Countryside Council for Wales (CCW) in 2005 and provides an assessment of the conservation status of Welsh Special Areas of Conservation (SACs) and Sites of Special Scientific Interest (SSSIs). It details the site condition assessments of 43 individual standing water features and provides overall assessments of the 13 SACs and 11 SSSIs in which they lie. Site condition is assessed using Common Standards Monitoring (CSM) methods, where specific habitat feature attributes are assessed against targets corresponding to ‘favourable’ condition. To make these assessments, data from CCW Contract Science Report no. 704 (Goldsmith et al. 2006) is employed, alongside further chemical and biological data collected by ENSIS Ltd. and the Environment Agency (EA) between 2003-2005. Data from previous reports and surveys is also utilised where available to provide a longer-term perspective and possible evidence of trends. The results of the site condition assessments are discussed in terms of general categories of impact (e.g. acidification or eutrophication). Where sites were in unfavourable condition, recommendations for further investigation and / or management are made. Reference is also made to Water Framework Directive (WFD) Risk Assessments and some attempt is made to relate condition assessment outcomes to the probability of sites failing to meet good ecological status by 2015 in accordance with the objectives of Article 4 of the WFD. Condition assessments for the oligotrophic to mesotrophic Welsh lake SACs (23 lakes) and SSSIs (7 lakes) with vegetation of the Littorelletea uniflorae and / or of the IsoëtoNanojuncetea, indicate that approximately 80 % of lakes of this type are currently in ‘unfavourable’ (60 %) or ‘unfavourable, recovering’ (20 %) condition. Only one SAC - Cadair Idris (3 lakes) – and three lakes within two other SACs are classified as ‘favourable’. Acidification is the primary reason for failure to meet favourable condition targets, particularly for SAC lakes. The recovery trends observed at a number of acid-impacted lakes most likely relate to reductions in atmospheric deposition of sulphur and nitrogen. It is expected that alkalinisation trends will continue provided that atmospheric deposition stabilises or continues to decrease. Nutrient enrichment, grazing pressure, sediment inwash, forestry operations and drawdown are further pressures that result in unfavourable condition assessment outcomes. Eutrophication is of particular concern amongst SSSI lakes of this type. All eleven Welsh lake SACs and SSSIs of the naturally eutrophic type (with Magnopotamion or Hydrocharition-type vegetation) or hard oligo-mesotrophic Chara spp. type are classified as ‘unfavourable’ (70 %) or ‘unfavourable, recovering’ (20 %), with one lake classified as ‘unfavourable, declining’. Eutrophication is the primary reason for failure to meet favourable condition targets. However, unlike acidification, eutrophication may come from both point and diffuse sources, and its effects may be exacerbated by local management practices such as grazing and fish stocking. For many eutrophied lakes there is scope to identify and reduce diffuse sources of nutrients within the catchment. However, residual sediment nutrient concentrations may be problematic, as may inappropriate fish communities resulting from past stocking practices. Eutrophication can dramatically alter the structure and function of a lake ecosystem; therefore carefully constructed management plans must be implemented if favourable condition is to be a realistic future target for impacted naturally eutrophic and hard-water Welsh lake SACs and SSSIs. Only one SAC in Wales is notified for the dystrophic lakes feature (2 lakes). This feature was provisionally classified as unfavourable. However, the targets for this habitat type may require refinement. The report concludes by discussing uncertainty in lake classification, data confidence concerns, CSM issues relating to survey methodology and the appropriateness of targets used for condition assessment. Comparisons between the CSM approach and other lake assessment methodologies are also considered. Overall recommendations for future monitoring and assessment are provided.

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