Approaches and methods used to assess ecological quality under European environmental legislation
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Benthic habitats and the macrobenthic communities they support form an integral component of ecological quality assessments in marine and estuarine waters. Good conceptual understanding of change in benthic community structure in relation to environmental disturbances has underpinned the development of a wide range of techniques to detect, describe and interpret change in habitat quality. Many of these techniques have been proposed as monitoring tools under European environmental Directives (e.g. Habitats Directive, HD; Water Framework Directive, WFD; Marine Strategy Framework Directive, MSFD). The primary aim of this thesis was to build on current scientific understanding of the performance and sensitivity of a range of techniques currently used to meet the provisions of environmental legislation. This body of work is comprised of 4 separate, yet related, studies. The HD and WFD both share the common overall goal of conserving biodiversity and good habitat quality, and focus on aspects of coastal and transitional water systems. This thesis proposes a pragmatic approach for the integration of habitat classification (sensu the HD) and Ecological Status (ES) assessments (sensu the WFD) in sedimentary habitats. Integration of the HD and WFD has the potential to strengthen both Directives by mutual enlightenment between assessment outputs. The proposed approach also has potential to provide a framework for applying Before-After Control-Impact (BACI) designs for assessing change at a regional level for the WFD and HD. Natural spatial and temporal variability in monitoring data has been shown to have a confounding effect on reliability of ES assessments using WFD Ecological Quality Ratios (EQRs). BACI designs have the potential to improve current environmental assessments by objectively accounting for the effects of natural variability thus allowing the effects of impacts to be discriminated more accurately and reliably. Similarly, increasing the reliability and robustness of habitats classifications and maps revealing their spatial distribution have potential to improve the effectiveness of environmental management, particularly the HD which in part focuses on the management of conservation sites. This thesis determined the performance of different sediment particle size analysis techniques in terms of the ability of their resulting sediment distributions to explain variance and patterns in faunal datasets. Using sediment distribution data that best explains the underlying pattern within faunal datasets will allow communities and biotopes to be resolved with greater confidence. These elements have the potential to improve the effectiveness of environmental management. This thesis also highlighted the implications of changing sampling strategies on the allocation of ES (sensu the WFD). Adopting single sample survey designs caused ES to be classified as lower when compared to a multiple sample survey design. Consequently, the effects of sampling design must be taken seriously when assessing ES, particularly if assessments form the basis of scientific advice used to inform management decisions. Similarly, the reliability of EQRs must be determined before the indices are used to assess ES to geographical locations and conditions for which the techniques were not originally designed. This thesis proposes a novel approach of using abundances of taxa higher than species with EQRs as an effective way of facilitating the transfer of WFD-type management to a new geographic region at Hong Kong, China. A number of member states, including Ireland, have expressed interest in adopting OSPAR's Ecological Quality Objective (EcoQO) framework to help meet their obligations under the MSFD, however, there are concerns as to the performance of EcoQOs in a real world situation. This thesis used time-series data to validate the application of OSPAR's EcoQO for tributyltin contamination in Irish waters. It is suggested that the quantified temporal responses of the EcoQO provided by the time-series data could be potentially be used to objectively track change in environmental quality over time.
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