Intercalibrating classifications of ecological status: Europe's quest for common management objectives for aquatic ecosystems.

Halting and reversing the deterioration of aquatic ecosystems requires concerted action across state boundaries and administrative barriers. However, the achievement of common management objectives is jeopardised by different national quality targets and ambitions. The European Water Framework Directive requires that quality classifications are harmonised via an intercalibration exercise, ensuring a consistent level of ambition in the protection and restoration of surface water bodies across the Member States of the European Union. We outline the key principles of the intercalibration methodology, review the achievements of intercalibration and discuss its benefits and drawbacks. Less than half of the required intercalibration has been completed, mostly due to a lack of national assessment methods. The process has fostered a scientific debate on ecological classification with important implications for environmental management. Despite a significant level of statistical abstraction, intercalibration yielded a fundamental and unified vision of what constitutes good ecology across Europe, in principle ensuring greater parity in the funds invested to achieve good ecological status.

An assessment of the risk to surface water ecosystems of groundwater P in the UK and Ireland.

A good quantitative understanding of phosphorus (P) delivery is essential in the design of management strategies to prevent eutrophication of terrestrial freshwaters. Most research to date has focussed on surface and near-surface hydrological pathways, under the common assumption that little P leaches to groundwater. Here we present an analysis of national patterns of groundwater phosphate concentrations in England and Wales, Scotland, and the Republic of Ireland, which shows that many groundwater bodies have median P concentrations above ecologically significant thresholds for freshwaters. The potential risk to receptor ecosystems of high observed groundwater P concentrations will depend on (1) whether the observed groundwater P concentrations are above the natural background; (2) the influence of local hydrogeological settings (pathways) on the likelihood of significant P transfers to the receptor; (3) the sensitivity of the receptor to P; and, (4) the relative magnitude of P transfers from groundwater compared to other P sources. Our research suggests that, although there is often a high degree of uncertainty in many of these factors, groundwater has the potential to trigger and/or maintain eutrophication under certain scenarios: the assumption of groundwater contribution to river flows as a ubiquitous source of dilution for P-rich surface runoff must therefore be questioned. Given the regulatory importance of P concentrations in triggering ecological quality thresholds, there is an urgent need for detailed monitoring and research to characterise the extent and magnitude of different groundwater P sources, the likelihood for P transformation and/or storage along aquifer-hyporheic zone flow paths and to identify the subsequent risk to receptor ecosystems.

Tissue nutrient signatures predict herbaceous-wetland community responses to nutrient availability.

• An extensive survey of European wetlands was undertaken to compare the importance of growing conditions vs functional characteristics of vegetation in determining N, P and K contents. • Stress-tolerator dominated stands (S) had consistently lower nutrient contents and higher N : P ratios whereas ruderal-dominated (R) stands displayed the opposite pattern. Competitor (C) and competitor-stress tolerator (CS) stands were intermediate to R and S. • These patterns were mostly preserved after removing covariation between vegetation and environment, thus indicating constitutional differences in nutrient signatures between functionally differentiated vegetation. C and R stands were least likely to be nutrient limited. Half of the S stands were probably P-limited but C, CS and R stands rarely or never experienced P limitation. Inferred colimitation by K was twice as frequent in S stands compared with other vegetation. • This study extends the evidence for syndromes of traits closely linked to nutrient use efficiency that increase fitness under particular growing conditions. It also highlights patterns at a community level across a wide range of wetland types and suggests that tissue nutrient signatures will have diagnostic value in predicting community responses to perturbation in nutrient availability.