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Durham, United Kingdom

Kelly M.,Bowburn Consultancy
Journal of Ecology and Environment

Diatoms have become an integral part of the UK's freshwater monitoring strategy over the past two decades, mostly in response to increasingly stringent European Union (EU) legislation. The use of diatoms is based on strong correlations between diatom assemblages and environmental variables, and from knowledge of the "expected" (= "reference") state of each river. The nationwide overview of the ecological health of rivers this gives allows those stretches of rivers which fail to meet EU criteria to be identified. This, in turn, allows appropriate remediation measures to be planned. Because diatom assemblages vary in space and time, even within a single water body, effective use of diatoms requires a consistent approach in order to minimise uncertainty. This includes the use of methods which comply with European Standards, a training and accreditation scheme for analysts, and a suite of quality assurance methods. Those aspects of uncertainty that cannot be readily controlled have been quantified and all estimates of ecological status are accompanied by the appropriate "confidence of class" and "risk of misclassification". This, in turn, helps planners prioritise those locations which are most likely to benefit from remediation. © 2013 The Ecological Society of Korea. Source

Schneider S.C.,Norwegian Institute for Water Research | Kahlert M.,Swedish University of Agricultural Sciences | Kelly M.G.,Bowburn Consultancy
Science of the Total Environment

Eutrophication and acidification are among the major stressors on freshwater ecosystems in northern Europe and North America, but possible consequences of interactions between pH and nutrients on ecological status assessment and species richness patterns have not previously been assessed. Using data from 52 river sites throughout Norway, we investigated the combined effects of pH and nutrients on benthic algae assemblages, specifically 1) taxa-specific couplings between nutrient and acidity traits, 2) the degree of consistency between different biotic indices, separately for nutrients and acid conditions, 3) the impact of pH on nutrient indices and phosphorus on indices of acid conditions, and 4) the impact of pH and phosphorus supply on diatom and non-diatom taxon richness. We found that 1) acid-tolerant taxa are generally associated with nutrient-poor conditions, with only a few exceptions; this is probably more a consequence of habitat availability than reflecting true ecological niches; 2) correlation coefficients between nutrient indices and TP, as well as acid conditions indices and pH were barely affected when the confounding factor was removed; 3) the association of acid-tolerant taxa with nutrient-poor conditions means that the lowest possible nutrient index at a site, as indicated by benthic algae, is lower at acid than at circumneutral sites. Although this may be an artifact of the datasets from which taxa-specific indicator values were derived, it could lead to a drift in nutrient indices with recovery from acidification; 4) the response of non-diatom taxon richness follows a complex pattern with a synergistic interaction between nutrient supply and pH. In contrast, diatom richness follows a simple additive pattern; this suggests structural differences between diatoms and non-diatom benthic algae in their response to nutrient supply and pH; diatom taxon richness tended to increase with nutrient supply, while non-diatom richness decreased. © 2012 Elsevier B.V. Source

Kelly M.,Bowburn Consultancy
Ecological Indicators

Many diatom-based methods have been proposed in recent years. Besse-Lototskaya et al. (2011) compare some of those developed for assessing inorganic nutrients. However, they fail to address the two questions of greatest interest to those who wish to use such metrics to inform decision-making. These questions are: what is the role of diatom-based trophic metrics in environmental management in Europe in the twenty-first century and do these indices represent causal relationships with underlying pressure gradients? The present economic climate means that Member States of the European Union will look more critically at all methods for assessing freshwater quality and developers need to ensure that their methods are "fit-for-purpose". © 2011 Elsevier Ltd. Source

The Water Framework Directive (WFD) embodies concepts of "ecological health". This essay extends this metaphor, looking at the ways in which ecologists should diagnose and treat "sick" ecosystems. Recent practice in the UK has been to develop multifunctional ecologists to act as ecological equivalents of "family doctors". This requires methods that can be used without high levels of specialisation and, in turn, allows individuals to gain deep knowledge of particular geographic areas. This system is under threat both from new scientific developments and from management innovations designed to reduce costs. The next stages of WFD implementation, however, will see a shift towards locally based problem-solving, where inherent uncertainties will require the exercise of professional judgement above and beyond evidence-based science. We need to encourage "breadth" as well as "depth" in ecological assessment methods and a three-tiered framework for this is described. © 2013 Elsevier Ltd. Source

Kelly M.,Bowburn Consultancy
European Journal of Phycology

The Water Framework Directive (WFD) provides the legal basis for water management in the European Union (EU). Twelve years after it was passed, all but five EU Member States had phytobenthos assessment methods for rivers, whilst nine had methods for lakes. Most are based on diatoms, although a few are supplemented by evaluations of non-diatoms and some include macroalgae as part of parallel macrophyte assessments. Norway is the exception, with assessment based on non-diatom algae alone. Over half of all states have methods based wholly or partly on weighted average metrics developed before the onset of the WFD, with nine choosing the Indice de Polluosensibilité Specifique. Such metrics generally have high correlations with the predominant nutrient or organic pollution gradient and, as such, represent pragmatic solutions to ecological status assessment. However, their widespread use raises questions about what, exactly, 'ecological status' means. Strong relationships with chemical pressure gradients may be a mixed blessing as pressure gradients are often composed of several intercorrelated variables, making it difficult to disentangle correlation and causation in the absence of ecophysiological studies of individual species. Moreover, the focus on strong relationships with chemical gradients means that most phytobenthos metrics describe the scale of hazard at a site rather than the risk posed to other trophic levels and to ecosystem services. This first generation of phytobenthos assessment tools may be inadequate when catchment managers need guidance on remediation strategies for particular water bodies. A second generation of assessment tools, focused on the fitness of the phytobenthos as part of aquatic ecosystems, rather than just as indicators of chemical conditions, is needed if the goal of good ecological status around Europe is to be achieved. © 2013 © British Phycological Society. Source

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