Assessment of the ecological status of European surface waters: a work in progress

Abstract

The 'normative definitions' of ecological water quality classes given by the Water Framework Directive (WFD) are narrative descriptions of the conditions present in water bodies of different qualities relative to reference conditions found in unimpacted sites. In order to fill these descriptions with a more solid content, the definitions have been a subject of intensive development of quantitative methodologies for ecological status assessment as well as for rules and criteria for setting of reference conditions and ecological status boundaries for classification of water bodies. In this article, we recall the basic principles of the WFD that sometimes have been overlooked and point out some gaps remained and problems arisen during the ongoing implementation of the directive. Defining type-specific reference conditions for water bodies and finding biological metrics that sensitively reflect only the anthropogenic deviations from those conditions are the biggest challenges that the ecological status assessment faces. So far, there is no guarantee that reference conditions are comparable across EU Member States due to a lack of common criteria, which need still to be elaborated. Defining site-specific reference conditions instead of type specific is a novel approach that allows for minimizing uncertainties introduced by applying broad types. Search for new metrics has led to a real boom of multimetric indices which ought to be the adequate tool to measure the multiple human impairments but which should pass a thorough check before being included in monitoring programs. Curiously, some biological indices constructed as surrogates for chemistry (especially nutrients) start 'living their own life' and continue indicating the disturbance when the controlling factors change. This shows the obvious advantage of biological indicators against chemical ones. New challenges to WFD implementation are brought about by the need to consider the effects of alien species and climate change in the assessment framework, and by the nonlinear dose-response relationships dominating in biological systems. Attempts to diminish uncertainties in quality assessment have become a new labour-intensive field for researchers

Macrophyte and macroinvertebrate patterns in unimpacted mountain rivers of two European ecoregions

“…The ecological status of a water body is defined as the deviation between the organisms identified there and the biological communities detected under reference conditions. Therefore, precise and efficient monitoring requires the correct identification of biological communities in reference conditions for each existing river type (Moss, 2008;Nõges et al, 2009;Demars et al, 2012;Mao & Richards, 2012). Ecological assessment based on reference conditions is used to measure streams' health, to identify degraded conditions and to monitor human impact or determine restoration effectiveness; it is also applied outside the European Union member states (Pond, 2012;Gerth et al, 2013;Kosnicki et al, 2014).…”

Overview and application of the National Aquatic Ecological Monitoring Program (NAEMP) in Korea

“…Various biological metrics, including individual and aggregated indices of algae, macrophytes, macroinvertebrates, and fish, have been proposed for various spatial extents, mostly in North America and Europe (Osborne and Sua´rez-Seoane, 2002;Hering et al, 2006;Pont et al, 2006;Johnson et al, 2007;Ode et al, 2008;Stoddard et al, 2008). Although uncertainties remain in applying these metrics in ecological regions and spatial scales that differ from those for which the metrics were developed and verified (Kelly et al, 2009;No˜ges et al, 2009), assessments of ecological status using biological indices and habitat condition have become drivers of water management and restoration practices.…”

Phytoplankton metrics response to the increasing phosphorus and nitrogen gradient in shallow lakes

“…In most cases, phytoplankton is controlled by P concentrations (e.g. DOKULIL, TEUBNER 2005) and TP can be a very good predictor of its development (LYCHE SOLHEIM et al 2008, NÕGES et al 2009). Despite this fact, total nitrogen can correlate very strongly with phytoplankton biomass and chlorophyll a concentration (CARSTENSEN, HENRIK-SEN 2009).…”

“…Therefore, it may be treated as an element in the assessment based on the taxonomic composition of phytoplankton assemblage. Each newly developed method for assessment ought to be a suitable tool to measure the composed anthropogenic damage and should be checked before being included in monitoring programs (NÕGES et al 2009). The Polish method has not yet been validated and tested on independent data.…”