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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    Piscivory and trophic position of Anguilla anguilla in two lakes: importance of macrozoobenthos density
    Dorner, H. ; Skov, C. ; Berg, S. ; Schulze, T. ; Beare, D.J. ; Velde, G. van der - \ 2009
    Journal of Fish Biology 74 (2009)9. - ISSN 0022-1112 - p. 2115 - 2131.
    perch perca-fluviatilis - fresh-water - european eel - nitrogen isotopes - mesotrophic lake - habitat use - food webs - fish - consumption - diet
    The feeding habits of the European eel Anguilla anguilla (> 300 mm total length, L-T) were compared in two lakes of different environmental state: Lake Gro ss er Vatersee (LGV), Germany (clear water, mesotrophic and submerged macrophytes), and Lake Vallum (LV), Denmark (turbid, eutrophic and no submerged macrophytes). The density of macrozoobenthos was higher in LV (3500 individuals m(-2)) than in LGV (1500 individuals m(-2)). The abundance of small prey fishes (40-99 mm L-T) was highest in LV. In LV, A. anguilla fed on macrozoobenthos, in particular, chironomid larvae. In LGV, A. anguilla used fishes as the main food component. Stable isotope analyses confirmed the stomach contents dietary results. The estimated mean +/- s.d. trophic positions of A. anguilla in LGV (3.7 +/- 0.2) was one level higher than those of fish in LV (2.7 +/- 0.2). Based on these results, it is concluded that piscivory among A. anguilla was generally controlled by the density of macrozoobenthos. Stable isotope analysis further indicated that A. anguilla may act as integrators between benthic and pelagic food webs when density of insect larvae is low.
    Towards a phylogenetic clarification of Lophiostoma / Massarina and morphologically similar genera in the Pleosporales
    Zhang, Y. ; Wang, H.K. ; Fournier, J. ; Crous, P.W. ; Jeewon, R. ; Pointing, S.B. ; Hyde, K.D. - \ 2009
    Fungal Diversity 38 (2009). - ISSN 1560-2745 - p. 225 - 251.
    submerged wood - ribosomal dna - fresh-water - hong-kong - fungi - ascomycota - revision - epitypification - teleomorph - sequences
    Lophiostoma, Lophiotrema and Massarina are similar genera that are difficult to distinguish morphologically. In order to obtain a better understanding of these genera, lectotype material of the generic types, Lophiostoma macrostomun, Lophiotrema nucula and Massarina eburnea were examined and are re-described. The phylogeny of these genera is investigated based oil the analysis of 26 Lophiostoma- and Massarina-like taxa and three genes - 18S, 28S rDNA and RPB2. These taxa formed five well-supported sub-clades in Pleosporales. This Study confirms that both Lophiostoma and Massarina are polyphyletic. Massarina-like taxa can presently be differentiated into two groups - the Lentithecium group and the Massarina group. Of these, the type species M. eburnea together with the Massarina group represents Massarina sensu stricto. Lophiostoma taxa Clustered in two groups - one group, including the type species L. macrostomum, is characterized by fusiform, hyaline one-septate ascospores which are pigmented and 3-septate when senescent, clavate asci, and apical structures which are highly variable, being crest-like in L. macrostomum, all umbilicate pore surrounded by 4-6 radial ridges in L. rugulosum, or papillate in L. glabrotunicatum. The second group comprises Lophiostoma species with heavily pigmented multi-septate ascospores and compressed crests. Lophiotrema species including the type species L. nucula form a monophyletic group. One new genus - Lentithecium with five new species - Lentithecium aquaticum, Lophiostoma glabrotunicatum, L. rugulosum, Lophiotrema brunneosporum and L. lignicola and three new combinations - Lentithecium arundinaceum, L. fluviatile and L. lineare are introduced in this paper.
    Phylogenetic and morphological assessment of two new species of Amniculicola and their allies (Pleosporales)
    Zhang, Y. ; Fournier, J. ; Crous, P.W. ; Pointing, S.B. ; Hyde, K.D. - \ 2009
    Persoonia 23 (2009). - ISSN 0031-5850 - p. 48 - 54.
    fresh-water - molecular characterization - gene-sequences - ribosomal dna - xylariaceae - fungi - china
    Two new species of Amniculicola, A. immersa sp. nov. and A. parva sp. nov. from submerged wood in a freshwater environment in Denmark and France are respectively described and illustrated. In addition, partial 28S rDNA sequence data is analysed to investigate their phylogenetic relationships with other pleosporalean taxa. All presently known Amniculicola species, A. immersa, A. lignicola and A. parva, form a robust clade together with the anamorphic species Anguillospora longissima, Spirosphaera cupreorufescens and Repetophragma ontariense. These six species, which are all from freshwater and mostly from Europe, constitute a well-supported group containing Pleospora rubicunda and Massariosphaeria typhicola. This putative monophyletic assemblage may represent an aquatic group in the Pleosporales. It is also pertinent that all five ascomycete taxa in this group stain their host substrates purple
    Lake and watershed characteristics rather than climate influence nutrient limitation in shallow lakes
    Kosten, S. ; Huszar, V.M. ; Mazzeo, N. ; Scheffer, M. ; Sternberg, L.S.L. ; Jeppesen, E. - \ 2009
    Ecological Applications 19 (2009)7. - ISSN 1051-0761 - p. 1791 - 1804.
    waterkwaliteit - voedingsstoffen - meren - stikstof - fosfor - cyanobacteriën - eutrofiëring - herstel - klimaat - zuid-amerika - primaire productie - water quality - nutrients - lakes - nitrogen - phosphorus - cyanobacteria - eutrophication - rehabilitation - climate - south america - primary production - phytoplankton community structure - fresh-water - meteoric precipitation - nitrogen-retention - subtropical lakes - trophic state - danish lakes - n-p - denitrification
    Both nitrogen (N) and phosphorus (P) can limit primary production in shallow lakes, but it is still debated how the importance of N and P varies in time and space. We sampled 83 shallow lakes along a latitudinal gradient (5°–55° S) in South America and assessed the potential nutrient limitation using different methods including nutrient ratios in sediment, water, and seston, dissolved nutrient concentrations, and occurrence of N-fixing cyanobacteria. We found that local characteristics such as soil type and associated land use in the catchment, hydrology, and also the presence of abundant submerged macrophyte growth influenced N and P limitation. We found neither a consistent variation in nutrient limitation nor indications for a steady change in denitrification along the latitudinal gradient. Contrary to findings in other regions, we did not find a relationship between the occurrence of (N-fixing and non-N-fixing) cyanobacteria and the TN:TP ratio. We found N-fixing cyanobacteria (those with heterocysts) exclusively in lakes with dissolved inorganic nitrogen (DIN) concentrations of
    Dynamic DGT speciation analysis and applicability to natural heterogeneous complexes
    Town, R.M. ; Chakraborty, P. ; Leeuwen, H.P. van - \ 2009
    Environmental Chemistry 6 (2009)2. - ISSN 1448-2517 - p. 170 - 177.
    trace-metal speciation - in-situ measurements - deposition potential sscp - thin-films dgt - humic acids - voltammetric techniques - dissociation kinetics - fulvic-acid - fresh-water - stripping chronopotentiometry
    Owing to their inherent heterogeneity, the thermodynamic stability of metal ion complexes with natural ligands is characterised by a distribution, and thus is a function of metal-to-ligand ratio. The kinetic features of such metal complexes are also distributed and can be probed by dynamic speciation techniques. The kinetic regime of the metal complex sample can be manipulated via the metal-to-ligand ratio, and the timescale over which kinetic parameters are actually in effect is defined by the window of the chosen technique. Here we detail the kinetic features of diffusive gradients in thin film (DGT), and show that the range of attainable measurement timescales (t) is rather limited: variation of the gel layer thickness practically allows only one order of magnitude in t to be scanned. The more effective use of DGT to probe the distribution of dynamic metal species in heterogeneous systems is via variation of the metal-to-ligand ratio in the sample solution. Compilation of the literature DGT data for natural waters shows that by assuming a Freundlich isotherm relationship, the degree of heterogeneity is reflected in the measured DGT concentration as a function of metal ion loading
    Impact of ionic strength on Cd(II) partitioning between alginate gel and Aqueous media
    Kalis, E.J.J. ; Davis, T.A. ; Town, R.M. ; Leeuwen, H.P. van - \ 2009
    Environmental Science and Technology 43 (2009)4. - ISSN 0013-936X - p. 1091 - 1096.
    heavy-metal biosorption - biotic ligand model - exchange properties - marine macroalga - divalent metals - charge-density - fresh-water - cell-walls - algae - removal
    Alginate gel is representative of polysaccharide-based components of cell walls which contain a large number of negatively charged functional groups. The structural charge gives rise to a Donnan potential in the gel, which impacts significantly on the partitioning of ions between the aqueous medium and the gel. We measured the Donnan potential and partitioning of Cd2+ in alginate gel as a function of ionic strength in the range 1-100 mM. The Cd2+ partition coefficient between gel and medium, as measured by in situ microelectrode voltammetry, reaches values between 10 and 100 in the 0.1-1 mM ionic strength range, and agrees well with Donnan partition calculations based on the charge density of the gels. The total Cd(II) concentration in the gel correlates approximately linearly with the free [Cd2+]gel. The results imply that metal ion activities in the biopolymer gel phase may generally differ drastically from those in the bulk medium to an extent that strongly depends on ionic strength. This feature must be taken into account in estimations of exposure conditions for predictions of bioavailability
    Decreasing eel stocks: survival of the fattest?
    Belpaire, C.G.L. ; Goemans, G. ; Quataert, P. ; Hagel, P. ; Boer, J. de - \ 2009
    Ecology of Freshwater Fish 18 (2009)2. - ISSN 0906-6691 - p. 197 - 214.
    anguilla-anguilla-l - european eel - fresh-water - silver eel - sexual-maturation - flame retardants - flanders belgium - temporal trends - thames estuary - sargasso sea
    Since the 1980s, the European eel Anguilla anguilla stock is in steep decline. Lipid reserves are essential to cover energetic requirements for silver eel migration and reproduction. Two large and independent data sets from Belgium and The Netherlands show an average one-third decrease in fat contents of yellow eels over the past 15 years. Also Le Cren's relative condition factor decreased. On the basis of the somatic energy reserves, reproductive potential of eels from various latitudes over Europe was estimated, assuming fat levels in yellow eel are indicative of those in silver eels. Only large individuals, females as well as males, with high lipid content seem to be able to contribute to the spawning stock. The decrease in fat content in yellow eels may be a key element in the stock decline and raises serious concerns about the chances of the stock to recover
    Fast response of lake plankton and nutrients to river inundations on floodplain lakes
    Roozen, F.C.J.M. ; Peeters, E.T.H.M. ; Roijackers, R.M.M. ; Wyngaert, I.J.J. van den; Wolters, H. ; Coninck, H.C. de; Ibelings, B.W. ; Buijse, A.D. ; Scheffer, M. - \ 2008
    River Research and Applications 24 (2008)4. - ISSN 1535-1459 - p. 388 - 406.
    danube restoration project - lower rhine - hydrological connectivity - community composition - fresh-water - egg banks - phytoplankton - system - zooplankton - diversity
    Key variables in ecosystems tend to operate on widely different time-scales. These time-scales become relevant when a disturbance rocks the ecosystem. Here we try to explain the fast dynamics of plankton and nutrients in the water column of floodplain lakes after disturbances (inundations). We take advantage of natural experiments, that is occasional massive overflow of floodplain lakes with river water. We sampled 10 lakes in two floodplains along the Dutch river Waal monthly for 3 years, capturing the impact of three inundation events. The inundations reset the plankton as well as chemical composition of most lakes to largely the same state. While biologically inert macro-ion data reflected a large and long lasting impact of the river water, dynamics of nutrients, phytoplankton and zooplankton communities between lakes diverged in a few weeks to regimes characteristic for the different lakes. While one spring inundation synchronized plankton dynamics to let the subsequent clear water phase occur at the same moment in different lakes, winter inundations did not have the same effect and apparently dynamics quickly diverged. Our results showed that effects of inundations and other processes that affect the state of the ecosystem should be studied considering the level of the slow components such as the sediment nutrient pool, fish stock and macrophyte communities. Plankton communities and lake water nutrient status give a practically instantaneous reflection of the condition of these slow components
    Migration history of North Sea houting (Coregonus oxyrinchus L.) caught in Lake IJsselmeer (The Netherlands) inferred from scale transects of 88SR:44 Ca ratios
    Borcherding, J. ; Pickhardt, C. ; Winter, H.V. ; Becker, J.S. - \ 2008
    Aquatic Sciences 70 (2008)1. - ISSN 1015-1621 - p. 47 - 56.
    inductively-coupled plasma - otolith microchemistry - mass-spectrometry - fresh-water - isotope analysis - plenary lecture - fish otoliths - lower rhine - icp-ms - strontium
    North Sea houting, Coregonus oxyrinchus, became extinct in the River Rhine in the 1940 s and was reintroduced in the 1990 s. To study the migration history of individuals, the 88Sr:44Ca ratio of scales of 39 houting (10¿44 cm TL) caught in Lake IJsselmeer was analysed using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Scales of houting inhabiting freshwater ponds and two Danish rivers containing the last original populations in the North Sea basin were used as controls. Fish that lived exclusively in freshwater had 88Sr:44Ca ratios of around 0.2 from the nucleus to the edge; 29 of the analysed houting from Lake IJsselmeer were of this type. Most of these were small, but some were mature and up to 42 cm in length. Seven houting had 88Sr:44Ca ratios over 0.27 from the nucleus to the scale maximum values, indicating migration to the sea at early life stages. Three houting with low 88Sr:44Ca ratios at the scale nucleus and increased 88Sr:44Ca ratios towards the scale edge probably lived in freshwater for a longer period after hatching and then moved to brackish/marine environments. The scale analysis indicates different migration patterns for houting in Lake IJsselmeer and provides evidence that this species (1) is sometimes able to pass the migratory barriers between the Wadden Sea and Lake IJsselmeer, and (2) does not need to migrate to sea to reach maturity.
    Effects of feed composition on life history developments in feed intake, metabolism, growth and body composition of European eel, Anguilla anguilla
    Heinsbroek, L.T.N. ; Hooff, P.L.A. ; Swinkels, W. ; Tanck, M.W.T. ; Schrama, J.W. ; Verreth, J.A.J. - \ 2007
    Aquaculture 267 (2007)1-4. - ISSN 0044-8486 - p. 175 - 187.
    trout oncorhynchus-mykiss - female atlantic salmon - rainbow-trout - compensatory growth - fresh-water - energy-metabolism - food-intake - protein - deposition - nutrient
    To examine the effect of feed composition on changes in feed intake and subsequent feed utilization with age, five populations of European eel, with an average initial body weight of 5 g each fed a different diet, were monitored for 302 d. The five feeds differed in their content of crude protein (33¿63% DM), crude fat (6¿28% DM) and calculated carbohydrates (NFE; 15¿42% DM) such that five levels of digestible protein/digestible energy (DP/DE) were realised: 13, 16, 21, 28 and 29 g MJ¿ 1. At three points in time, with three size groups, nitrogen and energy balance studies were conducted in which next to feed intake and growth also digestibilities of dry matter, protein, fat, NFE and energy as well as O2 consumption and NH4¿N excretion were measured. Due to the distinct life history of the semelparous, in the present study predominantly male eel, a well-defined goal in terms of mature size and composition could be inferred, presumably to maximize their lifetime reproductive output. In order to reach this goal the animal needs to survive and to grow and voluntary feed intake of the eels could be adequately described with the feed intake model `eating to requirements subject to constraints¿, where voluntary feed intake is considered to originate from a requirement for maintenance (survival) and a requirement for growth. Live weight gain is almost completely based on protein deposition (PD) and eels, like other animals, strive to reach a genetically determined growth potential (PDmax) thought to be driven by the difference from the mature protein mass (Ptmax). Body lipid content increases with size and varied with diet from a minimum of 25% at high DP/DE ratios to a maximum of 33% at low DP/DE ratios, at body weights of 130¿140 g. Preferable allocation of dietary protein to PD (protein sparing action of non-protein energy) was confirmed as marginal efficiency of protein utilization increased with decreasing DP/DE ratio from 0.29 to 0.54. Marginal energetic efficiency of PD, kp was 0.54 and marginal energetic efficiency of LD, kf varied from 0.67, indicating de novo lipid synthesis (from dietary protein) at high DP/DE ratios, to 0.93, indicating direct lipid synthesis (from dietary lipid) at low DP/DE ratios. Marginal efficiencies did not differ from those of other fish or other farm animals. Differences between fish species in feed intake and utilization of feeds differing in macronutrient composition, as well as life history developments in feed intake and feed utilization are therefore based on differences in growth rate, in turn with mature weight (Ptmax), and body composition (LD/PD ratio).
    Biocomplexity in a highly migratory pelagic marine fish , Atlantic herring
    Ruzzante, D.E. ; Mariani, S. ; Bekkevold, D. ; André, C. ; Mosegaard, H. ; Clausen, L.A.W. ; Dahlgren, T.G. ; Hutchinson, W.F. ; Hatfield, E.M.C. ; Torstensen, E. ; Brigham, J. ; Simmonds, E.J. ; Laikre, L. ; Larsson, L.C. ; Stet, R.J.M. ; Ryman, N. ; Carvalho, G.R. - \ 2006
    Proceedings of the Royal Society. B: Biological Sciences 273 (2006)1593. - ISSN 0962-8452 - p. 1459 - 1464.
    larvae clupea-harengus - north-sea - population-structure - anadromous fishes - fresh-water - diversity - ecosystem - recovery
    The existence of biologically differentiated populations has been credited with a major role in conferring sustainability and in buffering overall productivity of anadromous fish population complexes where evidence for spatial structure is uncontroversial. Here, we describe evidence of correlated genetic and life history (spawning season linked to spawning location) differentiation in an abundant and highly migratory pelagic fish, Atlantic herring, Clupea harengus, in the North Sea (NS) and adjacent areas. The existence of genetically and phenotypically diverse stocks in this region despite intense seasonal mixing strongly implicates natal homing in this species. Based on information from genetic markers and otolith morphology, we estimate the proportional contribution by NS, Skagerrak (SKG) and Kattegat and western Baltic (WBS) fish to mixed aggregations targeted by the NS fishery. We use these estimates to identify spatial and temporal differences in life history (migratory behaviour) and habitat use among genetically differentiated migratory populations that mix seasonally. Our study suggests the existence of more complex patterns of intraspecific diversity than was previously recognized. Sustainability may be compromised if such complex patterns are reduced through generalized management (e.g. area closures) that overlooks population differences in spatial use throughout the life cycle
    Effects of humic acid and competing cations on metal uptake by Lolium perenne
    Kalis, E.J.J. ; Temminghoff, E.J.M. ; Weng, L.P. ; Riemsdijk, W.H. van - \ 2006
    Environmental Toxicology and Chemistry 25 (2006)3. - ISSN 0730-7268 - p. 702 - 711.
    biotic ligand model - chemical speciation - lead bioaccumulation - nutrient solution - organic-matter - coastal diatom - cadmium uptake - trace-metals - ion-binding - fresh-water
    Within the biotic ligand model, which describes relationships between chemical speciation and metal binding at an organism's surface, multicomponent (long-term) metal uptake by plants has seldom been studied. In the present work, we exposed perennial ryegrass to nutrient solutions with two levels of Cd, Cu, Ni, Pb, and Zn (1 and 0.1 ¿M) and with or without 30 mg/L of humic acid. Iron and Mn concentrations were constant over all treatments. The hypothesis tested was that humic acid lowers the free and labile metal concentration and, therefore, reduces the metal uptake and, finally, the metal content of the plant. The free metal ion concentrations in the nutrient solutions were measured by the Donnan membrane technique and labile metal concentrations by diffusive gradients in thin-films. The metal content of the shoots depends on the metal content of the roots. The metal content of the roots is a function of the adsorption of metals on the root surface. In a multicomponent system at metal concentrations of 1 ¿M, humic acid decreased Cu, Pb, and Fe adsorption at the root surface, but it increased Cd, Zn, and Mn adsorption at the root surface. Complexation of cations such as Cu, Pb, and Fe with high affinity for (dissolved) organic matter may lead to increased uptake of cations with low affinity for organic matter (Ni, Zn, and Cd) because of competition between cations at the root surface. The results suggest that competition between metal ions can play a major role in multicomponent metal uptake, which has to be taken into account during risk assessments of metal-polluted soils.
    Kinetic limitations in measuring stabilities of metal complexes by Competitive Ligand Exchange-Adsorptive Stripping Voltammetry (CLE-AdSV)
    Leeuwen, H.P. van; Town, R.M. - \ 2005
    Environmental Science and Technology 39 (2005)18. - ISSN 0013-936X - p. 7217 - 7225.
    natural organic-ligands - san-francisco bay - copper complexation - atlantic-ocean - fresh-water - emiliania-huxleyi - dissolved copper - estuarine waters - surface waters - chemical speciation
    The kinetic limitations of Competitive Ligand Exchange-Adsorptive Stripping Voltammetry, CLE-AdSV, for the determination of very stable metal complexes are explained in detail. For a given type of metal, from a certain lower limit of the complex stability constant, K, the usual simple equilibrium interpretation of CLE-AdSV measurements is not generally valid. By critical assessment of data for natural waters we show that in many cases the reported stability constants appear to derive from nonequilibrium conditions in the bulk sample and hence overestimate the real values. Fe(III) is a special case due to the particular kinetic features of hydroxide as a ligand. Our results call for validation of such data by analysis on the basis of the kinetics involved and/or by independent kinetic-free experimental approaches. Earlier speculations from CLE-AdSV results on very strong ligands and derived features such as the potential bioavailability of trace metals in natural waters require reconsideration.
    Global distribution and sources of dissolved inorganic nitrogen export to the coastal zone: Results from a spatially explicit, global model
    Dumont, E.L. ; Harrison, J.A. ; Kroeze, C. ; Bakker, E.J. ; Seitzinger, S.P. - \ 2005
    Global Biogeochemical Cycles 19 (2005)GB4SO2. - ISSN 0886-6236 - p. np - np.
    marine ecosystems - world rivers - fresh-water - phosphorus - ocean - consequences - retention - system - impact - cycle
    Here we describe, test, and apply a spatially explicit, global model for predicting dissolved inorganic nitrogen (DIN) export by rivers to coastal waters (NEWS-DIN). NEWS-DIN was developed as part of an internally consistent suite of global nutrient export models. Modeled and measured DIN export values agree well (calibration R-2 = 0.79), and NEWS-DIN is relatively free of bias. NEWS-DIN predicts: DIN yields ranging from 0.0004 to 5217 kg N km(-2) yr(-1) with the highest DIN yields occurring in Europe and South East Asia; global DIN export to coastal waters of 25 Tg N yr(-1), with 16 Tg N yr(-1) from anthropogenic sources; biological N-2 fixation is the dominant source of exported DIN; and globally, and on every continent except Africa, N fertilizer is the largest anthropogenic source of DIN export to coastal waters.
    Insecticide species sensitivity distributions: importance of test species selection and relevance to aquatic ecosystems
    Maltby, L. ; Blake, N. ; Brock, T.C.M. ; Brink, P.J. van den - \ 2005
    Environmental Toxicology and Chemistry 24 (2005)2. - ISSN 0730-7268 - p. 379 - 388.
    insecticiden - waterkwaliteit - toxiciteit - ecologie - vatbaarheid - soorten - risicoschatting - aquatisch milieu - ecotoxicologie - aquatische ecosystemen - insecticides - water quality - toxicity - ecology - susceptibility - species - risk assessment - aquatic environment - ecotoxicology - aquatic ecosystems - ecological risk-assessment - fresh-water - cotton pyrethroids - surface waters - field - invertebrates - pesticides - responses - mesocosm
    Single-species acute toxicity data and (micro)mesocosm data were collated for 16 insecticides. These data were used to investigate the importance of test-species selection in constructing species sensitivity distributions (SSDs) and the ability of estimated hazardous concentrations (HCs) to protect freshwater aquatic ecosystems. A log-normal model was fitted to a minimum of six data points, and the resulting distribution was used to estimate lower (95% confidence), median (50% confidence), and upper (5% confidence) 5% HC (HC5) values. Species sensitivity distributions for specific taxonomic groups (vertebrates, arthropods, nonarthropod invertebrates), habitats (saltwater, freshwater, lentic, lotic), and geographical regions (Palaearctic, Nearctic, temperate, tropical) were compared. The taxonomic composition of the species assemblage used to construct the SSD does have a significant influence on the assessment of hazard, but the habitat and geographical distribution of the species do not. Moreover, SSDs constructed using species recommended in test guidelines did not differ significantly from those constructed using nonrecommended species. Hazardous concentrations estimated using laboratory-derived acute toxicity data for freshwater arthropods (i.e., the most sensitive taxonomic group) were compared to the response of freshwater ecosystems exposed to insecticides. The sensitivity distributions of freshwater arthropods were similar for both field and laboratory exposure, and the lower HC5 (95% protection with 95% confidence) estimate was protective of adverse ecological effects in freshwater ecosystems. The corresponding median HC5 (95% protection level with 50% confidence) was generally protective of single applications of insecticide but not of continuous or multiple applications. In the latter cases, a safety factor of at least five should be applied to the median HC5.
    Microsatellites within genes and ESTs of common carp and their applicability in silver crucian carp
    Yue, G.H. ; Ho, M.Y. ; Orban, L. ; Komen, J. - \ 2004
    Aquaculture 234 (2004)1-4. - ISSN 0044-8486 - p. 85 - 98.
    cross-species amplification - carassius-auratus gibelio - polymerase-chain-reaction - simple sequence repeats - cyprinus-carpio - dna polymorphisms - rapid isolation - compact genome - fresh-water - markers
    Thirty-six new microsatellites were identified from common carp (Cyprinus carpio L.) by screening through genes found in GenBank, EST sequences from a testis cDNA library and a genomic DNA library enriched for CA repeats. Eleven of the twenty-eight microsatellites identified from genes and ESTs were AT repeats, suggesting their high abundance in the genome of common carp. Characterization of the 36 microsatellites on a panel of 18 unrelated common carp individuals revealed that all, except two, were polymorphic with an average allele number of 7.3/locus (range: 2¿15 alleles/locus). The microsatellites located in genes and ESTs showed higher allele number than those eight which were isolated from a genomic DNA library (7.7/locus vs. 4.9/locus df=32, P
    Sediment pollution and predation affect structure and production of benthic macroinvertebrate communities in the Rhine-Meuse delta, The Netherlands
    Lange, H.J. de; Jonge, J. de; Besten, P.J. den; Oosterbaan, J. ; Peeters, E.T.H.M. - \ 2004
    Journal of the North American Benthological Society 23 (2004)3. - ISSN 0887-3593 - p. 557 - 579.
    waterverontreiniging - waterinvertebraten - zware metalen - sediment - besmetters - stroomvlakten - predatie - toxicologie - nederland - ecotoxicologie - rijn - maas - zuid-holland - water pollution - aquatic invertebrates - heavy metals - sediment - contaminants - floodplains - predation - toxicology - netherlands - ecotoxicology - river rhine - river meuse - zuid-holland - saint-francois quebec - acid volatile sulfide - invertebrate community - toxicological factors - population-dynamics - floodplain lakes - fresh-water - availability - bioavailability - extraction
    Most floodplain sediments of the rivers Rhine and Meuse in The Netherlands are moderately polluted with trace metals, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and other chemicals. The effects of these sediment-bound contaminants on the productivity of benthic macroinvertebrates are unclear. Sixteen locations along a pollution gradient were investigated in creeks in the Biesbosch floodplain area. Sediment samples were analyzed for bulk sediment characteristics and contaminants (total and bioavailable concentrations of trace metals, PAHs, and PCBs). Exclosures were used to study the effect of predation by fish and birds on macroinvertebrates. Macroinvertebrates were sampled and identified to species level, and production was estimated from biomass increases inside the exclosures during a 1-mo interval in spring
    Most floodplain sediments of the rivers Rhine and Meuse in The Netherlands are moderately polluted with trace metals, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and other chemicals. The effects of these sediment-bound contaminants on the productivity of benthic macroinvertebrates are unclear. Sixteen locations along a pollution gradient were investigated in creeks in the Biesbosch floodplain area. Sediment samples were analyzed for bulk sediment characteristics and contaminants (total and bioavailable concentrations of trace metals, PAHs, and PCBs). Exclosures were used to study the effect of predation by fish and birds on macroinvertebrates. Macroinvertebrates were sampled and identified to species level, and production was estimated from biomass increases inside the exclosures during a 1-mo interval in spring. Benthic macroinvertebrate species richness was negatively affected by sediment contamination. Production of oligochaetes and chironomids was not correlated with levels of contamination, but production of gastropods was negatively correlated with contamination. Environmental variables that reflected food availability (seston and sediment organic C) were positively correlated with contamination. Predation significantly reduced invertebrate biomass, but the effects of predation and sediment contamination were not correlated with each other. Our study suggested that the moderate levels of contamination affected the structure but not the productivity of the benthic macroinvertebrate community, probably because of the counteracting effects of contamination and associated surplus of food.
    Intracellular proliferation of Legionella pneumophila in Hartmannella vermiformis in aquatic biofilms grown on plasticized polyvinyl chloride
    Kuiper, M.W. ; Wullings, B.A. ; Akkermans, A.D.L. ; Beumer, R.R. ; Kooij, D. van der - \ 2004
    Applied and Environmental Microbiology 70 (2004)11. - ISSN 0099-2240 - p. 6826 - 6833.
    targeted oligonucleotide probes - potable-water - legionnaires-disease - transplant unit - fresh-water - tap water - amebas - multiplication - identification - acanthamoebae
    The need for protozoa for the proliferation of Legionella pneumophila in aquatic habitats is still not fully understood and is even questioned by some investigators. This study shows the in vivo growth of L. pneumophila in protozoa in aquatic biofilms developing at high concentrations on plasticized polyvinyl chloride in a batch system with autoclaved tap water. The inoculum, a mixed microbial community including indigenous L. pneumophila originating from a tap water system, was added in an unfiltered as well as filtered (cellulose nitrate, 3.0-mum pore size) state. Both the attached and suspended biomasses were examined for their total amounts of ATP, for culturable L. pneumophila, and for their concentrations of protozoa. L. pneumophila grew to high numbers (6.3 log CFU/cm(2)) only in flasks with an unfiltered inoculum. Filtration obviously removed the growth-supporting factor, but it did not affect biofilm formation, as determined by measuring ATP. Cultivation, direct counting, and 18S ribosomal DNA-targeted PCR with subsequent sequencing revealed the presence of Hartmannella vermiformis in all flasks in which L. pneumophila multiplied and also when cyclobeximide had been added. Fluorescent in situ hybridization clearly demonstrated the intracellular growth of L. pneumophila in trophozoites of H. vermiformis, with 25.9% +/- 10.5% of the trophozoites containing L. pneumophila on day 10 and >90% containing L. pneumophila on day 14. Calculations confirmed that intracellular growth was most likely the only way for L. pneumophila to proliferate within the biofilm. Higher biofilm concentrations, measured as amounts of ATP, gave higher L. pneumophila concentrations, and therefore the growth of L. pneumophila within engineered water systems can be limited by controlling biofilm formation.
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