Report: Effects monitoring for Wadden Sea organisms: Concepts; Opportunities (2004)»

“Summary: Biological effect monitoring provides the possibility to respond to a biological system (e.g. changes at population level: To link drainage, mortality, recruitment) with state variables of the system (substance concentrations in different environmental media such as water or sediment) (dose-effect analysis). The ecologically relevant concentration of potentially damaging substances in the sediment plays a key role in effect monitoring. For example, the concentration of heavy metals in the sediment exceeds that of the free water column by three to five orders of magnitude. The evaluation of the effects of potentially toxic substances at biological level is based on experimental studies on toxicokinetics, accumulation strategies and detoxification mechanisms of the affected organisms. Through ecotoxicological tests in the laboratory, the organisms are calibrated with regard to their reactions to different concentrations of substances or mixtures of substances. Various effect variables (endpoints) are tested, such as mortality, fertility or behavioral changes. Based on laboratory and outdoor studies, organisms (bio-indicators) which are particularly suitable for comparative measurements for environmental assessment are selected (Chapter 2: Requirements for effect monitoring). Effect monitoring is implemented in different project concepts. The evaluation of reactions of organisms or communities of organisms in the field to acute or chronic toxic effects (e.g. tanker accidents) or contamination gradients is the focus of organism-based approaches. Examples are shown on field bioassays with bivalve molluscs and for the evaluation of the benthic community as a result of a tanker accident. Species composition and nutritional types of the benthic community are also used to identify contaminated sediments in the coastal area (Section 3.1: organism-based approaches of effect monitoring). Project concepts with a focus on sediment toxicity are increasingly focusing on the use of ecotoxicological laboratory tests. Based on measured concentrations of substances in the sediment, bioassays are carried out or the sediment data are linked to the composition of the benthic community or fish populations. Using these projections, large-scale studies in the USA led to the environmental quality assessment of coastal marine areas (Section 3.2: Effect monitoring with focus on sediment toxicity). The concept of the sediment quality triad integrates results from chemical sediment analysis, biological observations in the field (benthic community) and ecotoxicological experiments (bioassays in the laboratory) and leads to a holistic environmental assessment. The conceptual framework of this approach offers variations of the methods of investigation and the evaluation of the data and is intended to show the existence, extent and reasons for system impairment. Ideally, sampling of the components sediment, water and organisms is carried out in parallel spatially and temporally. The results of the studies are combined and evaluated as summary indices, decision-making matrices or multivariate analysis. Case studies from the USA and Spain are presented (section 3.3: Sediment quality triad). The spatial relationship of a regionalised variable (e.g. biomass of an animal or plant species) can be estimated and visualised using geostatistical structural analysis. Due to the relevance for the evaluation of area-related variables for the assessment of coastal areas, this forward-looking statistical method is presented in detail and its application to environmental quality indices is shown_CUTABSTRACT_