H.J.R. Lenders

Ecotoxicogenomics: bridging the gap between genes and populations.

Ecotoxicogenomics might help solving open questions that cannot be answered by standard ecotoxicity tests currently used in environmental risk assessment. Changes in gene expression are claimed to serve potentially as early warning indicators for environmental effects and as sensitive and specific ecotoxicological end points. Ecotoxicogenomics focus on the lowest rather than the highest levels of biological organization. Our aim was to explore the links between gene expression responses and population level responses, both mechanistically (conceptual framework) and correlatively (Species Sensitivity Distribution). The effects of cadmium on aquatic species were compared for gene level responses (Lowest Observed Effect Concentrations) and individual level responses (median Lethal Concentrations, LC(50), and No Observed Effect Concentrations, NOEC). Responses in gene expression were on average four times above the NOEC and eleven times below the LC(50) values. Currently, use of gene expression changes as early warning indicators of environmental effects is not underpinned due to a lack of data. To confirm the sensitivity claimed by ecotoxicogenomics more testing at low concentrations is needed. From the conceptual framework, we conclude that for a mechanistic gene population link in risk management, research is required that includes at least one meaningful end point at each level of organization.

Exploring Public Perception of Non-native Species from a Visions of Nature Perspective

Not much is known about lay public perceptions of non-native species and their underlying values. Public awareness and engagement, however, are important aspects in invasive species management. In this study, we examined the relations between the lay public’s visions of nature, their knowledge about non-native species, and their perceptions of non-native species and invasive species management with a survey administered in the Netherlands. Within this framework, we identified three measures for perception of non-native species: perceived risk, control and engagement. In general, respondents scored moderate values for perceived risk and personal engagement. However, in case of potential ecological or human health risks, control measures were supported. Respondents’ images of the human–nature relationship proved to be relevant in engagement in problems caused by invasive species and in recognizing the need for control, while images of nature appeared to be most important in perceiving risks to the environment. We also found that eradication of non-native species was predominantly opposed for species with a high cuddliness factor such as mammals and bird species. We conclude that lay public perceptions of non-native species have to be put in a wider context of visions of nature, and we discuss the implications for public support for invasive species management.

Redefinition and elaboration of river ecosystem health : perspective for river management

This paper critically reviews developments in the conceptualization and elaboration of the River Ecosystem Health (REH) concept. Analysis of literature shows there is still no consistent meaning of the central concept Ecosystem Health, resulting in models (i.e. elaborations) that have unclear and insufficient conceptual grounds. Furthermore, a diverse terminology is associated with describing REH, resulting in confusion with other concepts. However, if the concept is to have merit and longevity in the field of river research and management, unambiguous definition of the conceptual meaning and operational domain are required. Therefore a redefinition is proposed, based on identified characteristics of health and derived from considering semantic and conceptual definitions. Based on this definition, REH has merit in a broader context of river system health that considers societal functioning next to ecological functioning. Assessment of health needs integration of measures of multiple, complementary attributes and analysis in a synthesized way. An assessment framework is proposed that assesses REH top-down as well as bottom up by combining indicators of system stress responses (i.e. condition) with indicators identifying the causative stress (i.e. stressor). The scope of REH is covered by using indicators of system activity, metabolism (vigour), resilience, structure and interactions between system components (organization). The variety of stress effects that the system may endure are covered by using biotic, chemical as well as physical stressors. Besides having a unique meaning, the REH metaphor has added value to river management by being able to mobilize scientists, practitioners and publics and seeing relationships at the level of values. It places humans at the centre of the river ecosystem, while seeking to ensure the durability of the ecosystem of which they are an integral part. Optimization of the indicator set, development of aggregation and classification methodologies, and implementation of the concept within differing international frames are considered main aims for future research.

Stakeholder value orientations in water management

Current water management issues are characterized by factual uncertainty, relating to limits of scientific knowledge, and value uncertainty, relating to the policy process of making subjective choices. Developing and informing approaches for integrated water management (IWM) requires bringing facts and values together. This study examines the way value orientations differentiate themselves among IWM stakeholders and assesses implications for the scientific support and policy context of integrated approaches. Using Q-methodology, we identify five orientations that represent characteristically different ways of valuing water systems and their management by stakeholders in terms of cognitive, ethical, and affective value priorities. The findings indicate that scientific support to substantiate IWM needs to be extended to include social sciences and that preferences regarding the outcome of policy strategies may differ between stakeholders due to divergent orientations. Decision makers can benefit from the understanding of different value orientations to resolve conflicts, develop planning scenarios, and build consensus.

The Importance of Hydrodynamics for Protected and Endangered Biodiversity of Lowland Rivers

This paper examines the relationship between protected and endangered riverine species (target species) and hydrodynamics in river-floodplain ecosystems, combining ecological and policy-legal aspects of biodiversity conservation in river management. The importance of different hydrodynamic conditions along a lateral gradient was quantified for various taxonomic groups. Our results show that (i) target species require ecotopes along the entire hydrodynamic gradient; (ii) different parts of the hydrodynamic gradient are important to different species, belonging to different taxonomic groups; (iii) in particular low-dynamic parts are important for many species and (iv) species differ in their specificity for hydrodynamic conditions. Many species of higher plants, fish and butterflies have a narrow range for hydrodynamics and many species of birds and mammals use ecotopes along the entire gradient. Even when focussing only on target species, the entire natural hydrodynamic gradient is important. This means that the riverine species assemblage as a whole can benefit from measures focussing on target species only. River reconstruction and management should aim at re-establishing the entire hydrodynamic gradient, increasing the spatial heterogeneity of hydrodynamic conditions.

BIO-SAFE : a method for evaluation of biodiversity values on the basis of political and legal criteria

This paper presents a Spreadsheet Application For Evaluation of BIOdiversity (BIO-SAFE) on the basis of political and legal criteria derived from national and international policy plans, laws, treaties and directives. The BIO-SAFE is developed as a management tool to optimise mutual attuning of nature conservation policies and other interests in spatial planning. Fields of application of BIO-SAFE comprise designs and evaluations of physical planning projects, environmental impact assessments and comparative landscape-ecological studies. Taxonomic groups involved in BIO-SAFE are higher plants, dragonflies and damselflies, butterflies, fish, amphibians, reptiles, birds and mammals. The development of BIO-SAFE was based on species characteristic of rivers and their floodplains, but the principles of the method can easily be applied to other ecosystems as well. The BIO-SAFE has been applied on behalf of a combined flood risk reduction and ecological rehabilitation plan for the Rijnwaarden floodplains (River Rhine, the Netherlands). Application to flora and fauna data available for this area showed that the BIO-SAFE method enables the user to express politically and legally based biodiversity values in quantitative terms and to compare biodiversity values for various taxonomic groups, landscape-ecological units (e.g. ecotopes) and physical planning scenarios. By linking habitat preferences of the species selected to ecotopes, the method also allows the user to derive relevant information at the ecosystem level. Because of its policy-based character, BIO-SAFE yields complementary information to more established ecological biodiversity indices.

Emergent principles for river management

Paradigms for land and water management are on the move. New approaches are said to be, or meant to be, more ‘participatory’, ‘integrated’, ‘adaptive’, ‘ecosystem-based’ and so on. The present paper explores emergent principles for land and water management in ecological management theory, environmental science and the social sciences. These principles comprise adaptive management, opportunity-driven analysis, visions of managers and the public, and co-management that includes local and supra-local rationality. The paper concludes that for river management, these principles largely reinforce each other. This lays a basis for a style of river management in which the river managers may continue to be the guardians of science-based and whole-basin rationality, while at the same time interacting more successfully with society.

Defining hotspots of characteristic species for multiple taxonomic groups in the Netherlands

Biogeographical zonation based on single taxa poses major limitations on planning for nature conservation. This paper identifies biogeographical patterns of multiple taxa in the Netherlands, where no endemics are present at species level, on the basis of characteristic species. We used occurrence data on five species groups in order to identify spatially coherent, ecologically important regions. TWINSPAN was used to cluster grid squares according to similarity in species composition for each taxonomic group. Species that are characteristic of each of the clusters were identified using a preference index, and corresponding clusters among the taxonomic groups were identified with Kappa statistics. Regions containing characteristic species for several taxonomic groups were defined as ‘hotspots’. Stepwise discriminant analysis was then used to characterize these hotspots according to differences in environmental conditions. The analysis yielded five regions that are clearly distinct in terms of species composition for individual taxonomic groups. Each region is characterized by a set of unique species that occur in the zonation of at least two of the taxonomic groups. Stepwise discriminant analysis revealed significant environmental differences among these regions. The concept of hotspots as operationalized in this study can make nature conservation planning more efficient. In combination, the hotspots defined here comprise the majority of the species occurring in the Netherlands for the studied groups. Therefore, this regionalization should be taken into account when prioritizing nature conservation efforts.

Historical rise of waterpower initiated the collapse of salmon stocks.

The collapse of Atlantic salmon (Salmo salar) stocks throughout North-Western Europe is generally ascribed to large-scale river regulation, water pollution and over-fishing in the 19th and 20th century. However, other causes have rarely been quantified, especially those acting before the 19th century. By analysing historical fishery, market and tax statistics, independently confirmed by archaeozoological records, we demonstrate that populations declined by up to 90% during the transitional period between the Early Middle Ages (c. 450–900 AD) and Early Modern Times (c. 1600 AD). These dramatic declines coincided with improvements in watermill technology and their geographical expansion across Europe. Our extrapolations suggest that historical Atlantic salmon runs must have once been very abundant indeed. The historical perspective presented here contributes to a better understanding of the primary factors that led to major declines in salmon populations. Such understanding provides an essential basis for the effective ecological rehabilitation of freshwater ecosystems.

Relating the Ecological and Legal Frameworks for Nature Conservation in Europe

Many species and habitats in the world have become rare or have entirely disappeared. The main causes are anthropogenic habitat destruction and fragmentation, deterioration of soil, water and air quality, hunting, and exploitation of species. To reverse these trends, the Convention on Biological Diversity opened for signature at the 1992 Rio Earth Summit. Legislation provides the necessary instruments for administrative-legal protection of nature. Ecology is an important science for providing the required knowledge and information on effects of human activities on species and their habitats. Because of the increased influence of legal instruments for nature conservation on decision-making concerning nature and landscape, the need for input of ecological knowledge and information increases. Insight into the relation between approaches and procedures of legislation on the one hand, and ecology on the other, is very important for optimal functioning of nature conservation programs.