Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Improving communication and validation of ecological models : a case study on the dispersal of aquatic macroinvertebrates
Augusiak, Jacqueline A. - \ 2016
Wageningen University. Promotor(en): Paul van den Brink, co-promotor(en): V. Grimm. - Wageningen : Wageningen University - ISBN 9789462579378 - 192
macroinvertebrates - aquatic invertebrates - ecological modeling - ecology - models - dispersal - environmental policy - macroinvertebraten - waterinvertebraten - ecologische modellering - ecologie - modellen - verspreiding - milieubeleid

In recent years, ecological effect models have been put forward as tools for supporting environmental decision-making. Often they are the only way to take the relevant spatial and temporal scales and the multitude of processes characteristic to ecological systems into account. Particularly for environmental risk assessments of pesticides the potential benefits of including modelling studies were recognized and a dialogue between different stakeholder groups was opened. Representatives from academia, pesticide-producing industries, and regulators are nowadays discussing their needs, possibilities, and ways of implementation for improving the use and usefulness of such models. However, it quickly became evident that not all involved parties possess the same background knowledge in regards to modelling terminology and model quality understanding. Proper communication of a given model's structure, robustness, and soundness is crucial to render a model of real use to the decision-making. Doubts about a model's quality and mode of operation may lead to an immediate rejection of the conclusions drawn from its estimations.

In this thesis, we addressed this point of concern, and performed a literature review focusing on aspects surrounding quality assessments, validation, and communication of models. "Validation" was identified as a catch-all term, which is thus useless for any practical purpose. Based on the review, we developed a framework that splits the seemingly blurry process into associated components and introduce the term ‘evaludation’, a fusion of ‘evaluation’ and ‘validation’, to describe the entire process of assessing a model's quality and reliability. Considering the iterative nature of model development, the modelling cycle, we identified six essential elements of evaludation: (i) ‘data evaluation’ for scrutinising the quality of numerical and qualitative data used for model development and testing; (ii) ‘conceptual model evaluation’ for examining the simplifying assumptions underlying a model's design; (iii) ‘implementation verification’ for testing the model's implementation in equations and as a computer programme; (iv) ‘model output verification’ for comparing model output to data and patterns that guided model design and were possibly used for calibration; (v) ‘model analysis’ for exploring the model's sensitivity to changes in parameters and process formulations to make sure that the mechanistic basis of main behaviours of the model has been well understood; and (vi) ‘model output corroboration’ for comparing model output to new data and patterns that were not used for model development and parameterisation.

In a subsequent step, we used the evaludation framework to re-evaluate and adjust the documentation framework TRACE (TRAnsparent and Comprehensive Eco- logical modelling; Schmolke et al. 2010), a general framework for documenting a model's rationale, design, and testing. TRACE documents should provide convincing evidence that a model was thoughtfully designed, correctly implemented, thoroughly tested, well understood, and appropriately used for its intended purpose. TRACE documents link the science underlying a model to its application, thereby also linking modellers and model users, for example stakeholders, decision makers, and developers of policies. TRACE thus becomes a tool for planning, documenting, and assessing model evaludation, which includes understanding the rationale behind a model and its envisaged use.

To provide an example of the measures that can be taken to increase general trust in a model's design and output, we chose MASTEP (Metapopulation model for Assessing Spatial and Temporal Effects of Pesticides) for a case study. MASTEP is an individual-based model used to describe the effects on and recovery of the water louse Asellus aquaticus after exposure to an insecticide in pond, ditch, and stream scenarios. The model includes processes of mortality of A. aquaticus, life history, random walk between cells and density dependence of population regulation. One of the submodels receiving particular criticism was the random walk procedure and the uncertainty attached to the parameters used. The parameters were estimated based on experimental studies performed under very limiting conditions.

We designed and performed experiments to derive more precise parameters and to better understand the movement behaviour of this freshwater isopod. The experimental procedure that we developed employed video tracking of marked individuals that were introduced alone or as part of a group of unmarked individuals into arenas of approximately 1m2 in size. We recorded the paths of the marked individuals under a set of different conditions, i.e. presence or absence of food or shelter, population density, and after sublethal exposure to chlorpyrifos and imidacloprid. Based on the experimental findings, we refined the movement modelling procedure used in MASTEP to derive more realistic dispersal estimates, with which we revisited a modelling study performed previously by Galic et al. (2012). In this study, the effects of pesticide application timing on population dynamics and recovery times were tested and compared to outcomes from previous versions. It was furthermore possible to integrate an increased level of environmental complexity that could not be addressed before due to a lack of data. Compared to former versions of the population model, recovery times did not change significantly when the same movement parameters were applied to all simulated individuals. This indicates that the previous assumptions already yielded robust estimations. Accounting for life stage dependent movement restraints, though, delayed recovery when exposure occurred shortly before a reproduction cycle. Based on these findings, it was concluded that an increase of ever more realism and environmental complexity in modelling studies needs to be done carefully on a case-by-case basis. Increased realism in models can introduce an unwarranted increase in model complexity and uncertainty, which is not always supporting an improved credibility level of a model.

Despite the need for basic ecological research for more comprehensive ecological models, we further argue that a modelling study in general can benefit greatly from an improved plan that considers communication needs from the start. Considering such needs early on can help develop a time- and cost-saving strategy for model testing and data collection, while providing a thorough understanding of a model's underlying mechanisms across several layers of stakeholder groups.

Assessing the effects of chemicals on aquatic microbial ecosystems
Rocha Dimitrov, M. - \ 2016
Wageningen University. Promotor(en): Hauke Smidt; Paul van den Brink. - Wageningen : Wageningen University - ISBN 9789462576667 - 264 p.
aquatic ecosystems - microorganisms - macroinvertebrates - microbial ecology - aquatic fungi - chemicals - tebuconazole - fungicide residues - pesticides - marine sediments - toxicity - enrofloxacin - fluoroquinolones - zooplankton - phytoplankton - antibiotic resistance - periphyton - bacteria - ecological risk assessment - aquatische ecosystemen - micro-organismen - macroinvertebraten - microbiële ecologie - waterschimmels - chemicaliën - tebuconazool - fungicidenresiduen - pesticiden - mariene sedimenten - toxiciteit - enrofloxacine - fluoroquinolonen - zoöplankton - fytoplankton - antibioticaresistentie - perifyton - bacteriën - ecologische risicoschatting
How to assess species richness along single environmental gradients? Implications of potential versus realized species distributions
Goethem, T.M.W.J. van; Huijbregts, M.A.J. ; Wamelink, G.W.W. ; Schipper, A.M. - \ 2015
Environmental Pollution 200 (2015). - ISSN 0269-7491 - p. 120 - 125.
sensitivity distributions - field data - plant - diversity - abundance - macroinvertebrates - acidification - consequences - biodiversity - assemblages
Quantifying relationships between species richness and single environmental factors is challenging as species richness typically depends on multiple environmental factors. Recently, various methods have been proposed to tackle this challenge. Using a dataset comprising field observations of grassland vegetation and measured pH values, we compared three methods for deriving species richness response curves. One of the methods estimates species richness close to the maximum species richness observed at the sites, whereas the other two provide estimates of the potential species richness along the environmental gradient. Our response curves suggest that potential species richness of grasslands is slightly more sensitive to acidification than realized plant species richness. However, differences in corresponding environmental quality standards (EQS) for acidification were small compared to intrinsic spatial differences in natural soil pH, indicating that natural background values are more important to consider in the derivation of EQS for pH than methodological differences between the three approaches.
Two approaches using traits to assess ecological resilience: A case study on earthworm communities
Lange, H.J. de; Kramer, K. ; Faber, J.H. - \ 2013
Basic and Applied Ecology 14 (2013)1. - ISSN 1439-1791 - p. 64 - 73.
river floodplains - species traits - wet grassland - biodiversity - diversity - macroinvertebrates - lumbricidae - oligochaeta - populations - pollutants
The relation between biological diversity and ecosystem functioning is a central theme in ecology. Ecological traits of species are often regarded as a link between structure and function, and trait distributions in a community may change in response to environmental stressors. Likewise, resilience in a community may be derived from the diversity in traits and trait values relevant to a particular stressor. We combine two approaches to test this: a novel trait frequency analysis and a multivariate ordination approach. The two methods are applied on a case study of an earthworm community in a frequently flooded floodplain in the Netherlands. Periodic flooding in floodplains restricts population growth and recolonization of earthworms. The strategies employed by different earthworm species for coping with this stress can be described by a combination of ecological traits. From the literature we compiled 10 ecological traits for the earthworm species encountered along an inundation gradient in the Duursche Waarden floodplain area flanking the river IJssel. Trait frequency analysis showed a greater diversity at low elevation sites of traits considered to be associated to flood tolerance, suggesting greater community resilience to flooding. The ordination analysis using trait composition provided information on which trait classes in the community were related with the inundation stress. Results from both analyses showed that important traits in species to deal with flooding are active dispersal, high hydrophily, diapause and parthenogenetic reproduction. Thus, a further understanding of community resilience was gained by combining traditional ordination analysis with trait diversity analysis
Activated carbon in sediment remediation : benefits, risks and perspectives
Kupryianchyk, D. - \ 2013
Wageningen University. Promotor(en): Bart Koelmans, co-promotor(en): Tim Grotenhuis. - S.l. : s.n. - ISBN 9789461734310 - 262
waterbodems - verontreinigde sedimenten - ecotoxicologie - remediatie - actieve kool - macroinvertebraten - benthos - waterorganismen - bioaccumulatie - water bottoms - contaminated sediments - ecotoxicology - remediation - activated carbon - macroinvertebrates - aquatic organisms - bioaccumulation
Klassieke verontreinigingen zoals hydrofobe organische verbindingen (HOCs) komen uiteindelijk vaak in waterbodems terecht. Deze waterbodems kunnen hierdoor zelf een bron van verontreiniging worden en zo een risico vormen voor aquatische organismen en voor de mens. Traditionele manieren om waterbodems te reinigen, zoals baggeren en in situ capping, zorgen voor een grote verstoring van het benthische milieu en zijn niet altijd effectief, terwijl zij wel hoge kosten met zich meebrengen. Daarom is het nodig om nieuwe methoden voor reiniging van waterbodems te ontwikkelen die makkelijker zijn, minder kosten en minder verstorend zijn dan de bestaande methoden. De afgelopen jaren is de mogelijkheid onderzocht om adsorberende materialen zoals actieve kool (AC) toe te voegen aan verontreinigde waterbodems om zo de HOC concentratie in het water te verminderen. Dit onderzoek heeft als doel om het effect van toevoegen van AC op HOC blootstelling en toxiciteitsafname voor bentische organismen en gemeenschappen beter te begrijpen, om zo het gat tussen laboratorium en veld te dichten.
Letter to the editor: A new perspective for phytobenthos in the European Water Framework Directive
Besse-Lototskaya, A.A. ; Verdonschot, P.F.M. ; Coste, M. ; Vijver, B. van de - \ 2012
Ecological Indicators 18 (2012). - ISSN 1470-160X - p. 705 - 708.
diatom communities - streams - rivers - indicators - macroinvertebrates - eutrophication - ecoregions - gradients - typology - ecology
Acute toxicity tests with Daphnia magna, Americamysis bahia, Chironomus riparius and Gammarus pulex and implications of new EU requirenments for the aquatic effect assessment of insecticides
Brock, T.C.M. ; Wijngaarden, R.P.A. van - \ 2012
Environmental Science and Pollution Research 19 (2012)8. - ISSN 0944-1344 - p. 3610 - 3618.
lambda-cyhalothrin - pyrethroid insecticide - risk-assessment - chlorpyrifos - exposure - invertebrates - mesocosms - community - model - macroinvertebrates
Threshold concentrations for treatment related effects of 31 insecticides, as derived from aquatic micro-/mesocosm tests, were used to calibrate the predictive value of the European Tier-1 acute effect assessment on basis of laboratory toxicity tests with Daphnia magna, Chironomus spp., Americamysis bahia and Gammarus pulex. The acute Tier-1 effect assessment on basis of Daphnia (EC(50)/100) overall was protective for organophosphates, carbamates and most pyrethroids but not for neonicotinoids and the majority of insect growth regulators (IGRs) in the database. By including the 28-day water-spiked Chironomus riparius test, the effect assessment improves but selecting the lowest value on basis of the 48-h Daphnia test (EC50/100) and the 28-day Chironomus test (NOEC/10) is not fully protective for 4 out of 23 insecticide cases. An assessment on basis of G. pulex (EC(50)/100) is sufficiently protective for 15 out of 19 insecticide cases. The Tier-1 procedure on basis of acute toxicity data (EC(50)/100) for the combination of Daphnia and A. bahia and/or Chironomus (new EU dossier requirements currently under discussion) overall is protective to pulsed insecticide exposures in micro-/mesocosms. For IGRs that affect moulting, the effect assessment on basis of the 48-h Chironomus test (EC(50)/100) may not always be protective enough to replace that of the water-spiked 28-day C. riparius test (NOEC/10) because of latency of effects.
Biodiversity value of agricultural drainage ditches; a comparative analysis of the aquatic invertebrate fauna of ditches and small lakes.
Verdonschot, R.C.M. ; Keizer-Vlek, H.E. ; Verdonschot, P.F.M. - \ 2011
Aquatic conservation: marine and freshwater ecosystems 21 (2011)7. - ISSN 1052-7613 - p. 715 - 727.
fresh-water invertebrates - species richness - habitat complexity - ponds - dispersal - landscape - diversity - streams - macroinvertebrates - extrapolation
1. Drainage ditches are a common aquatic habitat in the lowland agricultural landscape of north-western Europe. The invertebrate fauna of these waters is poorly known compared with that of the semi-natural wetland fragments found in this region. While most wetlands are designated as nature reserves, drainage ditches are generally viewed purely as hydrological infrastructure in support of agriculture. 2. To assess the conservation value for aquatic invertebrates of these man-made habitats compared with that of wetland fragments, the taxonomic composition and life-history characteristics of invertebrate assemblages inhabiting nine small lakes and nine ditches in peatlands in the Netherlands were compared, as well as the environmental characteristics potentially influencing assemblage structure. 3. Although ditches comprised a smaller water volume, contained less diverse vegetation, displayed larger fluctuations in nutrient concentrations and were regularly managed, the total number of invertebrate taxa recorded per taxonomic group was comparable with that in small lakes, as was the number of nationally uncommon to very rare taxa. 4. Similarity in life-history characteristics between the two water-body types was high, except that a higher proportion of atmospheric air breathers was found in ditches, and more plant miners and collector–filterers in small lakes. 5. On a regional scale, a relatively high inter-ditch taxon dissimilarity was observed, resulting in total diversity estimates for ditches exceeding those of small lakes. 6. This study showed that drainage ditches can be a significant habitat type for aquatic invertebrates. In the Netherlands, water bodies in peatland agricultural areas can contain a diverse invertebrate fauna, similar to that of water bodies in nearby nature reserves.
Effects of malathion and carbendazim on Amazonian freshwater organisms: comparison of tropical and temperate species sensitivity distributions and water quality criteria
Rico Artero, A. ; Waichman, A.V. ; Geber-Correa, R. ; Brink, P.J. van den - \ 2011
Ecotoxicology 20 (2011)4. - ISSN 0963-9292 - p. 625 - 634.
aquatic ecosystems - brazilian amazon - risk-assessment - rainbow-trout - pesticides - toxicity - invertebrates - macroinvertebrates - ecotoxicology - environment
The risk assessment of pesticides for freshwater ecosystems in the Amazon has relied on the use of toxicity data and water quality criteria derived for temperate regions due to a lack of ecotoxicological studies performed with indigenous species. This leaves an unknown margin of uncertainty for the protection of Amazonian ecosystems, as differences in environmental conditions and species sensitivity are not taken into account. To address this issue, the acute toxic effects of malathion (an organophosphorus insecticide) and carbendazim (a benzimidazole fungicide) were assessed on five fish and five freshwater invertebrates endemic to the Amazonian region. Subsequently, the intrinsic sensitivity of Amazonian and temperate freshwater species was compared using the species sensitivity distribution (SSD) concept. Amazonian species sensitivity to malathion was found to be similar to that of their temperate counterparts, with LC50 values ranging between 111 and 1507 g/l for fish species and 2.1426 g/l for arthropod species. However, Amazonian fish appeared to be slightly less sensitive for carbendazim than temperate fish with LC50 values ranging between 1648 and 4238 g/l, and Amazonian invertebrates were found to be significantly more resistant than their temperate counterparts, with LC50 values higher than 16000 g/l. The results of this study suggest that for these compounds, the use of water quality criteria derived with laboratory toxicity data for temperate species will result in a sufficient protection level for Amazonian freshwater organisms. Recommendations for further research include the validation of threshold concentrations derived with temperate standard test species and with the SSD model with semi-field experiments considering larger assemblages of indigenous species under local environmental conditions.
Conducting model ecosystem studies in tropical climate zones: lessons learned from Thailand and way forward
Daam, M.A. ; Brink, P.J. van den - \ 2011
Environmental Pollution 159 (2011)4. - ISSN 0269-7491 - p. 940 - 946.
fresh-water microcosms - sahelian temporary ponds - fungicide carbendazim - insecticide chlorpyrifos - cyanobacterial dominance - risk-assessment - zooplankton - invertebrates - impact - macroinvertebrates
Little research has been done so far into the environmental fate and side effects of pesticides in the tropics. In addition, those studies conducted in tropical regions have focused almost exclusively on single species laboratory tests. Hence, fate and effects of pesticides on higher-tier levels have barely been studied under tropical conditions. To address this lack of knowledge, four outdoor aquatic model ecosystem experiments using two different test systems were conducted in Thailand evaluating the insecticide chlorpyrifos, the herbicide linuron and the fungicide carbendazim. Results of these experiments and comparisons of recorded fate and effects with temperate studies have been published previously. The present paper discusses the pros and cons of the methodologies applied and provides indications for i) possible improvements; ii) important aspects that should be considered when performing model ecosystem experiments in the tropics; iii) future research.
Optimizing the use of activity traps for aquatic biodiversity studies
Verdonschot, R.C.M. - \ 2010
Journal of the North American Benthological Society 29 (2010)4. - ISSN 0887-3593 - p. 1228 - 1240.
sloten - zoetwaterecologie - bemonsteren - ditches - freshwater ecology - sampling - gammarus-pulex - diel activity - invertebrates - stream - macroinvertebrates - ecology - catches - samples - food - lake
I investigated the effectiveness of activity traps for macroinvertebrate monitoring in shallow, heavily vegetated drainage ditches and explored 2 ways to optimize the use of activity traps for monitoring purposes. I tested the effects of trapping duration (48, 96, and 168 h) and use of attractants (bait and preconditioned leaves). The number of taxa and individuals captured increased with trapping duration. Based on the taxon accumulation curves, deployment times of 48 h and 96 h were equally efficient in capturing new taxa, but a trapping duration of 168 h was much more efficient and resulted in a larger number of taxa collected with every new sample added. Of the attractants offered in the traps, only bait caused differences in the macroinvertebrate assemblage recorded. After 48 h, more predators were captured in traps with bait than in control traps and traps with preconditioned leaves. This effect disappeared with longer trapping duration. Because of their relatively low labor requirements and high level of standardization, activity traps appear to be a valuable tool in lentic biodiversity surveys, especially when deployed for a longer period than has usually been reported. The use of bait is advisable only if capture of specific taxa is required and not for standard monitoring purposes.
A comparative analysis of restoration measures and their effects on hydromorphology and benthic invertebrates in 26 central and southern European rivers.
Jähnig, S.C. ; Brabec, K. ; Buffagni, A. ; Erba, S. ; Lorenz, A. ; Ofenböck, T. ; Verdonschot, P.F.M. ; Hering, D. - \ 2010
Journal of Applied Ecology 47 (2010)3. - ISSN 0021-8901 - p. 671 - 680.
long-term recovery - stream restoration - ecological quality - habitat structure - diversity - macroinvertebrates - success - fish
1. Hydromorphological river restoration usually leads to habitat diversification, but the effects on benthic invertebrates, which are frequently used to assess river ecological status, are minor. We compared the effects of river restoration on morphology and benthic invertebrates by investigating 26 pairs of non-restored and restored sections of rivers in Austria, Czech Republic, Germany, Italy and the Netherlands. 2. Sites were grouped according to (1) region: central Europe vs. southern Europe; (2) river type: mountain vs. lowland rivers; (3) restoration approach: active vs. passive restoration and (4) a combination of these parameters. All sites were sampled according to the same field protocol comprising hydromorphological surveys of river and floodplain mesohabitats, microhabitats at the river bottom and habitat-specific sampling of benthic invertebrates. Restoration effects were compared using Shannon–Wiener Indices (SWIs) of mesohabitats, microhabitats and invertebrate communities. Differences in metric values between non-restored and restored sites were compared for 16 metrics that evaluated hydromorphology and the benthic invertebrate community. 3. Mean SWIs differed for both mesohabitats (1·1 non-restored, 1·7 restored) and microhabitats (1·0 non-restored, 1·3 restored), while SWIs for invertebrate communities were not significantly different (2·4 non-restored, 2·3 restored). Meso- and microhabitat metrics in the restored sections were usually higher compared with the non-restored sections, but the effects on invertebrate metrics were negligible. 4. Measures in southern Europe and mountainous regions yielded larger differences between non-restored and restored sections of rivers. Differences in the meso- and microhabitat metrics were largest for actively restored sections of central European mountain rivers and rivers from southern Europe, followed by passively restored mountain rivers in central Europe. The smallest differences were observed for lowland sites. There was no significant restoration effect on invertebrate metrics in any categories. 5. Synthesis and applications. Restoration measures addressing relatively short river sections (several hundred metres) are successful in terms of improving habitat diversity of the river and its floodplain. Active restoration measures are suitable if short-term changes in hydromorphology are desired. To realize changes in benthic invertebrate community composition, habitat restoration within a small stretch is generally not sufficient. We conclude that restoring habitat on a larger scale, using more comprehensive measures and tackling catchment-wide problems (e.g. water quality, source populations) are required for a recovery of the invertebrate community.
Direct and Indirect Effects of the Fungicide Carbendazim in Tropical Freshwater Microcosms
Daam, M.A. ; Satapornvanit, K. ; Brink, P.J. van den - \ 2010
Archives of Environmental Contamination and Toxicology 58 (2010)2. - ISSN 0090-4341 - p. 315 - 324.
risk-assessment - pesticide use - impact - macroinvertebrates - responses - toxicity - thailand - quality
Direct and indirect effects of the fungicide carbendazim on ecosystem structure and functioning were studied =8 weeks after application (nominal concentrations: 0, 3.3, 33, 100, and 1000 µg/L) to outdoor microcosms in Thailand. Direct effects on macroinvertebrates are discussed in detail in a separate article. The present article presents the effects on other end points and discusses the hypothesized ecologic effect chain. Negative treatment effects on the zooplankton community were only recorded for the highest carbendazim treatment (NOECcommunity = 100 µg/L). The rotifer Keratella tropica, cladocerans (Moina micrura, Ceriodaphnia cornuta, and Diaphanosoma sp.), and cyclopoid copepods were decreased or even eliminated at this treatment level. The decrease in zooplankton and macroinvertebrate abundances was accompanied by an increase in numbers of several tolerant invertebrates, presumably caused by a release from competition and predation. The death of sensitive invertebrates probably also led to an overall decreased grazing pressure because increased levels of chlorophyll-a and bloom of the floating macrophyte Wolffia sp. were noted. The increase in primary producers is discussed to be the probable cause of changes in physicochemical water conditions, eventually resulting in an anoxic water layer during the last 3 weeks of the experiment. This is likely to have resulted in decreased invertebrate abundances noted in that period. Furthermore, the decreased decomposition of Musa (banana) leaves observed 8 weeks after application is considered to be the indirect effect of a decreased microbial activity resulting from these anoxic water conditions, rather than a direct toxic effect of carbendazim
Principal response curves technique for the analysis of multivariate biomonitoring time series
Brink, P.J. van den; Besten, P.J. den; Vaate, A. bij de; Braak, C.J.F. ter - \ 2009
Environmental Monitoring and Assessment 152 (2009)1-4. - ISSN 0167-6369 - p. 271 - 281.
artificial substrate - water-quality - macroinvertebrates - predation - community - invasion - rivers - rhine
Although chemical and biological monitoring is often used to evaluate the quality of surface waters for regulatory purposes and/or to evaluate environmental status and trends, the resulting biological and chemical data sets are large and difficult to evaluate. Multivariate techniques have long been used to analyse complex data sets. This paper discusses the methods currently in use and introduces the principal response curves method, which overcomes the problem of cluttered graphical results representation that is a great drawback of most conventional methods. To illustrate this, two example data sets are analysed using two ordination techniques, principal component analysis and principal response curves. Whereas PCA results in a difficult-to-interpret diagram, principal response curves related methods are able to show changes in community composition in a diagram that is easy to read. The principal response curves method is used to show trends over time with an internal reference (overall mean or reference year) or external reference (e.g. preferred water quality or reference site). Advantages and disadvantages of both methods are discussed and illustrated
Reduction of discharge peaks : effects of the construction of a water retention pond
Hoorn, M.W. van den; Verdonschot, P.F.M. - \ 2007
laaglandgebieden - waterlopen - fluviatiele erosie - rivierafvoer - fluctuaties - waterdieren - biodiversiteit - macroinvertebraten - lowland areas - streams - stream erosion - stream flow - fluctuations - aquatic animals - biodiversity - macroinvertebrates
Most Dutch lowland streams experience increased discharge fluctuations, both peaks and droughts, as a result of increasing drained and paved areas. Large discharge fluctuations result in changes in stream morphology and macroinvertebrate communities. Measures to retain runoff water during wet periods can reduce discharge fluctuations and restore both morphology and biodiversity. Retention of water runoff proved to be an effective technique to reduce discharge fluctuations and improve the hydromorphological and ecological quality of this lowland stream
Substrate preference : in sandy lowland streams 1 an experimental approach
Dekkers, T.B.M. ; Verdonschot, P.F.M. - \ 2007
substraten - ecologische verstoring - trichoptera - macroinvertebraten - substrates - ecological disturbance - macroinvertebrates
Hydromorphological conditions in lowland streams will change due to an increase of discharge peaks. Substrate stability, which is a key parameter at habitat scale for macroinvertebrates, will decrease. This poster shows laboratory experiments that were used to examine substrate preferences of three species of Trichoptera that represent stream specialists (Halesus radiatus, Micropterna sequax and Chaetopteryx villosa), and three stream ubiquists (Anabolia nervosa, Limnephilus lunatus and Mystacides longicornis). Knowledge on preferences is needed as reference to evaluate hydromorphologic disturbance
Sediment stability and macroinvertebarte composition
Siedlecka, A.M. ; Hoorn, M.W. van den; Verdonschot, P.F.M. - \ 2007
klimaatverandering - waterinvertebraten - doorspoelen - sediment - macroinvertebraten - climatic change - aquatic invertebrates - flushing - macroinvertebrates
Poster about the effects of climate change on aquatic fauna, especially the macroinvertebrates
Macrophyte communities in unimpacted European streams: variability in assemblage patterns, abundance and diversity
Baattrup-Pedersen, A. ; Szoszkiewicz, K. ; Nijboer, R.C. ; O'Hare, M. ; Ferreira, T. - \ 2006
Hydrobiologia 566 (2006)1. - ISSN 0018-8158 - p. 179 - 196.
species composition - plant-communities - system - macroinvertebrates - eutrophication - design - rivers
Macrophytes are an important component of aquatic ecosystems and are used widely within the Water Framework Directive (WFD) to establish ecological quality. In the present paper we investigated macrophyte community structure, i.e., composition, richness and diversity measures in 60 unimpacted stream and river sites throughout Europe. The objectives were to describe assemblage patterns in different types of streams and to assess the variability in various structural and ecological metrics within these types to provide a basis for an evaluation of their suitability in ecological quality assessment. Macrophyte assemblage patterns varied considerably among the main stream types. Moving from small-sized, shallow mountain streams to medium-sized, lowland streams there was a clear transition in species richness, diversity and community structure. There was especially a shift from a predominance of species-poor mosses and communities dominated by liverwort in the small-sized, shallow mountain streams to more species-rich communities dominated by vascular plants in the medium-sized, lowland streams. The macrophyte communities responded to most of the features underlying the typological framework defined in WFD. The present interpretation of the WFD typology may not, however, be adequate for an evaluation of stream quality based on macrophytes. First and most important, by using this typology we may overlook an important community type, which is characteristic of small-sized, relatively steep-gradient streams that are an intermediate type between the small-sized, shallow mountain streams and the medium-sized, lowland streams. Second, the variability in most of the calculated metrics was slightly higher when using the pre-defined typology. The consistency of these results should be investigated by analysing a larger number of sites. Particularly the need of re-defining the typology to improve the ability to detect impacts on streams and rivers from macrophyte assemblage patterns should be investigated. Electronic supplementary material Electronic supplementary material is available for this article at and accessible for authorised users.
Establishing reference conditions for European streams
Nijboer, R.C. ; Johnson, R.K. ; Verdonschot, P.F.M. ; Sommerhäuser, M. ; Buffagni, A. - \ 2004
Hydrobiologia 516 (2004)1-3. - ISSN 0018-8158 - p. 91 - 105.
macroinvertebrates - quality
The European Water Framework Directive stipulates that Member States have to assess the ecological status of a water body by comparing the present to the expected reference condition. In the AQEM project participating countries used the criteria from the Water Framework Directive to select reference sites for each stream type. The purpose of this study was to evaluate the suitability of these criteria and to validate the reference conditions chosen, by comparing the classification of sites before analysis with the final assessment of the sites using the assessment system which was developed within the AQEM project. Our study showed that not all criteria for reference conditions could be met for all stream types. This implies that `true' reference sites could not be selected for all stream types within the AQEM project. In our study, the differences between ecoregions, countries, and stream types were interpreted in terms of human impact. Validation of reference conditions showed differences between classification of sites as reference sites based on criteria to be used in the field and directly interpreting environmental or biological data and the result of the final assessment system. In some countries it was not possible to select reference conditions, because most of the a priori criteria were met. For example, reference conditions for Dutch stream types were established using historical data and predictions based on data from other geographical regions. Using data from adjacent countries appeared to be a feasible method for establishing reference conditions. Reference sites taken from other geographical areas represented a higher ecological quality than the Dutch sites of good ecological quality. However, metric results showed a large overlap between good and high ecological status. Historical information, on the other hand, was not found to be useful in metric calculations because of the confounding differences in sampling methods. One strong advantage of using historical information is that rare species that are locally extinct but still occur in the same stream type in other geographical areas can be added to the expected reference conditions. When and which methods can be used for establishing reference conditions is illustrated in a decision tree.
Overview and application of the AQEM assessment system
Hering, D. ; Moog, O. ; Sandin, L. ; Verdonschot, P.F.M. - \ 2004
Hydrobiologia 516 (2004)1-3. - ISSN 0018-8158 - p. 1 - 20.
macroinvertebrates - quality - streams
The main objective of the European Union (EU) funded project AQEM1was to develop a framework of an assessment system for streams in Europe based on benthic macroinvertebrates that fulfils the requirements of the EU Water Framework Directive. Initial assessment methods for 28 European stream types and more generally applicable tools for stream biomonitoring in Europe were generated. The development of the system was based on a newly collected data set covering stream types in Austria, the Czech Republic, Germany, Greece, Italy, The Netherlands, Portugal and Sweden. Altogether, 901 benthic invertebrate samples were taken using a standardised multi-habitat sampling procedure and a large number of parameters describing the streams and their catchments was recorded for all sampling sites. From the stream and catchment characteristics measures of stress were derived. A large number of metrics was tested independently for each of the stream types, to identify the response of each metric to degradation of a site. This process resulted in up to 18 core metrics for the individual stream types, which were combined into a different multimetric index in each country. The multimetric AQEM assessment system is used to classify a stream stretch into an Ecological Quality Class ranging from 5 (high quality) to 1 (bad quality) and often provides information on the possible causes of degradation. AQEM provides a taxa list of 9557 European macroinvertebrate taxa with associated autecological information, a software package for performing all the calculations necessary for applying the multimetric AQEM assessment system and a manual describing all aspects of the application of the system from site selection to data interpretation.
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