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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    Over forty years of lowland stream restoration : Lessons learned?
    Reis Oliveira, Paula C. dos; Geest, Harm G. van der; Kraak, Michiel H.S. ; Westveer, Judith J. ; Verdonschot, Ralf C.M. ; Verdonschot, Piet F.M. - \ 2020
    Journal of Environmental Management 264 (2020). - ISSN 0301-4797
    Catchment scale - Clean water act - Freshwater restoration - Legislation - Restoration techniques - WFD

    Stream restoration efforts have increased, but the success rate is still rather low. The underlying reasons for these unsuccessful restoration efforts remain inconclusive and need urgent clarification. Therefore, the aim of the present study was to evaluate over 40 years of stream restoration to fuel future perspectives. To this purpose we evaluated the influence of policy goals on stream restoration efforts, biophysical restoration objectives, restoration measures applied including the scale of application and monitoring efforts. Information was obtained from five stream restoration surveys that were held among the regional water authorities in the Netherlands over the last 40 years and from an analysis of the international scientific publications on stream restoration spanning the same time period. Our study showed that there was a considerable increase in stream restoration efforts, especially motivated by environmental legislation. However, proper monitoring of the effectiveness of the measures was often lacking. Furthermore, a mismatch between restoration goals and restoration measures was observed. Measures are still mainly focused on hydromorphological techniques, while biological goals remain underexposed and therefore need to be better targeted. Moreover, restoration practices occur mainly on small scales, despite the widely recognized relevance of tackling multiple stressors acting over large scales for stream ecosystem recovery. In order to increase the success rate of restoration projects, it is recommended to improve the design of the accompanying monitoring programmes, allowing to evaluate, over longer time periods, if the measures taken led to the desired results. Secondly, we advise to diagnose the dominant stressors and plan restoration measures at the appropriate scale of these stressors, generally the catchment scale.

    Freshwater ecoacoustics: Listening to the ecological status of multi-stressed lowland waters
    Lee, Gea H. van der; Desjonquères, Camille ; Sueur, Jérôme ; Kraak, Michiel H.S. ; Verdonschot, Piet F.M. - \ 2020
    Ecological Indicators 113 (2020). - ISSN 1470-160X
    Dissolved oxygen dynamics - Invertebrates - Passive acoustic monitoring - Water quality assessment

    A major challenge in water quality assessment is to identify suitable indicators to monitor and assess the effects of anthropogenic stressors on the ecological status of freshwater ecosystems. Passive acoustic monitoring is a novel approach that could potentially be used to detect invertebrate species and ecological processes such as dissolved oxygen dynamics in freshwater environments. The aim of the present study was to evaluate to what extent sounds can be used for water quality assessment. We performed a field study to relate acoustic indices to the intensity of several stressors, the invertebrate community composition and the dissolved oxygen dynamics in 20 temperate lowland streams and drainage ditches impacted to a varying degree by agricultural activities and discharges from waste water treatment plants. Our results showed that the recorded acoustic patterns were primarily associated with the fluctuation in dissolved oxygen saturation, while specific frequency bands could be related to the sound-producing invertebrate community. We observed that acoustic indices do not allow to detect the adverse effects of anthropogenic stressors on the invertebrate community composition, presumably due to the prevalence of Heteroptera which are relatively insensitive to stressors, but make a lot of sounds. A strong relation between acoustic indices and oxygen fluctuation indicate that passive acoustic monitoring may be used to estimate metabolism in water bodies. We suggest that the next step in freshwater ecoacoustics will be to precisely characterise each source of sound emitted during the processes of primary production, respiration and re-aeration, in order to distinguish these parameters. This may overcome some of the challenges encountered in the estimation of metabolism from diel dissolved oxygen curves.

    Persist or perish: critical life stages determine the sensitivity of invertebrates to disturbances
    Lee, Gea H. van der; Kraak, Michiel H.S. ; Verdonschot, Ralf C.M. ; Verdonschot, Piet F.M. - \ 2020
    Aquatic Sciences 82 (2020)2. - ISSN 1015-1621
    Agapetus fuscipes - Bioassessment - Discharge - Life cycle - Lowland streams

    A large proportion of studies assessing the impact of disturbances on the invertebrate community composition focus on a single life stage, assuming that those are an adequate indicator of environmental conditions. The effect of a specific disturbance may, however, depend on the life stage of the exposed organism. Therefore, we focused on the effect of spates on the caddisfly Agapetus fuscipes CURTIS (Trichoptera: Glossosomatidae) during different larval stages. A 2 year field study was performed in which we measured the discharge dynamics and population development of A. fuscipes in four lowland streams in The Netherlands. A stage-structured population model (i.e. StagePop) was used to test the impact of peak discharge on the different life stages, as larval instars 1–4 were not effectively sampled in the field. Four different mortality rates in response to spates were simulated, including a constant low, a constant high, a decreasing and an increasing impact per larval stage. This way, we were able to show a potential association between spates and population declines, where the stage-population model including decreasing impact by spates with increasing larval life stage most accurately described the population development of the larval instars 5–8. Focusing only on late instars could thus potentially result in underestimation of the effects of spates on this species. In conclusion, determination of responses of critical life stages to specific disturbances may help to identify the causes of the presence and absence of species, and thereby aid more effective management and restoration of degraded aquatic systems.

    Responses of macroinvertebrate communities to land use specific sediment food and habitat characteristics in lowland streams
    Reis Oliveira, Paula C. dos; Kraak, Michiel H.S. ; Pena-Ortiz, Michelle ; Geest, Harm G. van der; Verdonschot, Piet F.M. - \ 2020
    Science of the Total Environment 703 (2020). - ISSN 0048-9697
    C/N ratio - Fatty acids - Food resource - GLM - Macroinvertebrate indices - Substrate cover

    The input of land use specific organic matter into lowland streams may impact sediment characteristics in terms of food resources and habitat structure, resulting in differences in macroinvertebrate community composition. Therefore, we investigated to what extent land use specific sediment food and habitat characteristics structure macroinvertebrate communities. To this purpose linear multiple regression models were constructed, in which macroinvertebrate biotic indices were considered as response variables and sediment characteristics as predictor variables, analysed in 20 stream stretches running through five different land use types. Sediment characteristics and macroinvertebrate community composition were land use specific. The carbon/nitrogen (C/N) ratio, woody debris substrate cover and the origin of fatty acids influenced macroinvertebrate community composition. Shannon-Wiener diversity was better explained by fatty acids origin, such as in grassland streams, where a higher relative content of plant derived fatty acids related to a higher macroinvertebrate diversity. In cropland and wastewater treatment plant (WWTP) streams with a low C/N ratio and dominated by microbial derived fatty acids, higher abundances of Oligochaeta and Chironomus sp. were observed. Ephemeroptera, Plecoptera, and Trichoptera (EPT) richness was positively related to woody debris substrate cover, which only occurred in forest streams. Hence, macroinvertebrate community composition was influenced by the origin of the organic material, being either allochthonous or autochthonous and when autochthonous being either autotrophic or heterotrophic. It is therefore concluded that sediment food and habitat characteristics are key ecological filters.

    Spatiotemporal heterogeneity in lowland streams : A benthic macroinvertebrate perspective
    Brouwer, Jan de - \ 2019
    University of Amsterdam (UvA). Promotor(en): P.F.M. Verdonschot; M.H.S. Kraak, co-promotor(en): R.C.M. Verdonschot; A.A. Besse-Lototskaya. - Amsterdam : Universiteit van Amsterdam - 189
    In lowland streams, spatiotemporal heterogeneity of habitat structures and flow together shape the physical environment that affects biota on different scales. However, it is still unclear on which scale these key factors have the strongest effect on benthic macroinvertebrates. At the same time there is an urgent need to improve the ecological quality of lowland streams in terms of biodiversity. Therefore, this thesis aimed at identifying the relevant scales of spatiotemporal heterogeneity for benthic macroinvertebrates in lowland streams. To this purpose, species specific ranges of conditions, thresholds and requirements were studied to test the hypothesis that moderate spatial and temporal heterogeneity at the meso- and micro-scale carries the highest macroinvertebrate diversity in lowland streams and to determine the optimal conditions for characteristic running water species to improve future restoration efforts. The results presented in this thesis unraveled the key components of spatiotemporal heterogeneity in lowland streams from a benthic macroinvertebrate perspective at different scales, showing that the interactions between flow and complex habitat structures shape macroinvertebrate communities through the persistence of macroinvertebrates and their habitat on a microhabitat scale. In lowland streams moderate dynamic flow, the presence of complex habitat structures and a mixture of more and less durable habitat patches are key to providing benthic macroinvertebrates with resources, oxygen, food and shelter. The interplay of these key components results in a continuously evolving spatially heterogeneous environment suitable for a wide array of species. This way, complex habitat structures enable highly biodiverse and resilient macroinvertebrate assemblages, despite dynamic discharge patterns.
    Bedrijfsleven opgeroepen samen op te trekken bij voedseleducatie
    Zeinstra, Gertrude - \ 2019
    Land use affects lowland stream ecosystems through dissolved oxygen regimes
    Reis Oliveira, Paula C. dos; Geest, Harm G. van der; Kraak, Michiel H.S. ; Verdonschot, Piet F.M. - \ 2019
    Scientific Reports 9 (2019)1. - ISSN 2045-2322

    The aim of the present study was to assess the impact of surrounding land use on the structure and functioning of lowland stream ecosystems. To this end, five different land use types were selected (forest, extensive grassland, intensive grassland, cropland and wastewater treatment plant) each represented by four replicate streams, in which diel dissolved oxygen concentrations were recorded, sediment and water quality parameters were measured and macroinvertebrate community composition was determined. Chironomus sp., Oligochaeta and Gastropoda dominated the cropland and wastewater treatment plant (WWTP) streams, while Plecoptera and most Trichoptera only occurred in forest and extensive grassland streams. Forest streams communities were related to a high oxygen saturation, a high C/N ratio in the sediment and woody debris and coarse particulate organic matter (CPOM) substrate cover. Macroinvertebrate communities in cropland and WWTP streams were related to a low oxygen saturation in water and sediment and high concentrations of dissolved nitrogen, phosphorus and carbon. It is concluded that land use specific impacts on lowland streams are likely exerted via fine sediment accumulation in deposition zones, affecting oxygen regimes, sediment oxygen demand and stream metabolism, ultimately changing macroinvertebrate community composition. This study supports therefore the importance of including the catchment scale in ecological stream quality assessments, combining structural and functional endpoints.

    Jolijn Zwart-Van Kessel: ‘Smaaklessen en EU-schoolfruit naar hoger plan tillen’
    Zwart-van Kessel, Jolijn - \ 2019
    Door de dam heen : Soort- en rivier specifieke effecten van dammen op Europese trekvissen
    Puijenbroek, Peter van; Buijse, Tom ; Kraak, Michiel H.S. ; Verdonschot, P.F.M. - \ 2019
    Visionair : het vakblad van sportvisserij Nederland 13 (2019)51. - ISSN 1569-7533 - p. 28 - 31.
    Quantifying cumulative stress acting on macroinvertebrate assemblages in lowland streams
    Vries, Jip de; Kraak, Michiel H.S. ; Verdonschot, Ralf C.M. ; Verdonschot, Piet F.M. - \ 2019
    Science of the Total Environment 694 (2019). - ISSN 0048-9697
    Ecological water quality - Instream stressors - Lowland stream - Macroinvertebrates - Quantification method

    Macroinvertebrates in lowland streams are exposed to multiple stressors from the surrounding environment. Yet, quantifying how these multiple stressors impact macroinvertebrate assemblages is challenging. The aim of this study was to develop a novel method to quantify the cumulative stress acting on macroinvertebrate assemblages in lowland streams. To this purpose, we considered 22 stressors from different stressor categories such as hydrological, morphological and chemical stressors, acting over multiple spatial scales ranging from instream to the catchment scale. Stressor intensity was categorized into classes based on impact on the macroinvertebrate assemblages. The main stream was divided into segments, after which for each stream segment, the cumulative stressor contribution from headwater catchments, from the riparian zone and from upstream was calculated. To validate the cumulative stress quantification method, the lowland stream Tungelroyse Beek in the Netherlands was used as a case study. For this stream it was shown that independently derived ecological quality scores based on macroinvertebrate samples collected at multiple sites along the stream decreased with increasing calculated cumulative stress scores, supporting the design of the cumulative stress quantification method. Based on the contribution of each specific stressor to the cumulative stress scores, the reasons for the absence and presence of macroinvertebrate species may be elucidated. Hence, the cumulative stress quantification method may help to identify and localize the most stringent stressors limiting macroinvertebrate assemblages, and can thereby provide a better focus for management resources.

    Lowland stream restoration by sand addition: Impact, recovery, and beneficial effects on benthic invertebrates
    Reis Oliveira, Paula C. dos; Kraak, Michiel H.S. ; Verdonschot, Piet F.M. ; Verdonschot, Ralf C.M. - \ 2019
    River Research and Applications 35 (2019)7. - ISSN 1535-1459 - p. 1023 - 1033.
    channel incision - instream habitat restoration - macroinvertebrates - rheophilic species - sand addition - sedimentation

    Up to now, most lowland stream restoration projects were unsuccessful in terms of ecological recovery. Aiming to improve the success of stream restoration projects, a novel approach to restore sandy-bottom lowland streams degraded by channel incision was launched, consisting of the addition of sand to the stream channel in combination with the introduction of coarse woody debris. Yet it remained unknown whether this novel measure of sand addition is actually effective in terms of biodiversity improvements. The aim of the present study was therefore to evaluate if sand addition can improve hydromorphological stream complexity on the short term leading to an increase in macroinvertebrate biodiversity. To this end, particle transport, water depth, current velocity, dissolved oxygen dynamics, and sediment composition were measured. The response of the macroinvertebrate community composition was determined at different stages during the disturbance and short-term recovery process. Immediately downstream the sand addition site, transport and sedimentation of the sand were initially intense, until an equilibrium was reached and the physical conditions stabilized. The stream section matured fast as habitat formation took place within a short term. Macroinvertebrate diversity decreased initially but recovered rapidly following stabilization. Moreover, an increase in rheophilic taxa was observed in the newly formed habitats. Thus, although sand addition initially disturbed the stream, a relatively fast physical and biological recovery occurred, leading to improved instream conditions for a diverse macroinvertebrate community, including rheophilic taxa. Therefore, we concluded that sand addition is a promising restoration measure for incised lowland streams.

    Effect-based nationwide surface water quality assessment to identify ecotoxicological risks
    Baat, M.L. de; Kraak, M.H.S. ; Oost, R. van der; Voogt, P. de; Verdonschot, P.F.M. - \ 2019
    Water Research 159 (2019). - ISSN 0043-1354 - p. 434 - 443.
    Bioassay battery - Micropollutants - Passive sampling - Water framework directive - Water monitoring

    A large portion of the toxic effects observed in surface waters cannot be attributed to compounds regularly measured by water authorities. Hence, there is an urgent need for an effect-based monitoring strategy that employs bioassays to identify environmental risks. The aim of the present study was to perform an effect-based nationwide water quality assessment to identify ecotoxicological risks in a wide variety of surface waters. At 45 locations silicone rubbers and polar organic chemical integrative samplers were exposed to surface water for 6 weeks. Alongside the passive samplers an in-situ daphnid test was performed. Subsequent to field exposure, accumulated compounds were extracted from the passive samplers after which a battery of in vivo and in vitro bioassays was exposed to the extracts. The bioassay battery was selected such that it could identify the risks posed by a wide range of chemical pollutants and their transformation products, while simultaneously allowing for targeted identification of groups of compounds that cause specific effects. Bioassay responses were compared to effect-based trigger values to identify potential ecotoxicological risks at the investigated locations. Responses were observed in all bioassays, and trigger values were exceeded in 9 out of the 21 applied assays, allowing for ranking of the investigated locations based on ecotoxicological risks. No relationship between land use and the identification of ecotoxicological risks was observed. Based on the results, considerations regarding future improvements of effect-based monitoring are given. It is concluded that effect-based water quality assessment allowed prioritization of sites based on ecotoxicological risks, identified the presence of hazardous compounds regardless of being listed as priority substances, and meanwhile could prevent costly chemical analysis at sites with low ecotoxicological risks.

    The significance of refuge heterogeneity for lowland stream caddisfly larvae to escape from drift
    Brouwer, J.H.F. de; Kraak, M.H.S. ; Besse-Lototskaya, A.A. ; Verdonschot, P.F.M. - \ 2019
    Scientific Reports 9 (2019)1. - ISSN 2045-2322

    The process of macroinvertebrate drift in freshwater lowland streams is characterized by dislodgement, drift distance and subsequent return to the bottom. Refuges are important to all drift phases, since they may help larvae to avoid dislodgement and to escape from drift, even more so if the refuge structure is complex and heterogeneous. The aim of the present study was therefore to determine the influence of refuge heterogeneity on the ability of caddisfly larvae to return to the bottom from drift and to avoid secondary dislodgement. To this purpose a series of indoor flume experiments were undertaken, testing six Limnephilidae (Trichoptera) species, that occur on a gradient from lotic to lentic environments. Bed morphology (plain, refuges with or without leaf patches) and flow velocity (low (0.1 m/s), intermediate (0.3 m/s) and high (0.5 m/s) were manipulated. We showed that all species were favoured by refuges and that especially for species on the lentic end of the gradient (L. lunatus, L. rhombicus and A. nervosa), the ability to escape from drift and to avoid secondary dislodgement was increased. Moreover, we showed that all species spent more time in refuges than in open channel parts and more time in heterogeneous refuges (leaf patches) than in bare refuges, the latter being especially the case for larvae of the lotic species. For lentic species, not well adapted to high flow velocity, refuges are thus crucial to escape from drift, while for the lotic species, better adapted to high flow velocity, the structure of the refuge becomes increasingly important. It is concluded that refuges may play a crucial role in restoring and maintaining biodiversity in widened, channelized and flashy lowland streams.

    Dissolved oxygen dynamics in drainage ditches along a eutrophication gradient
    Lee, Gea H. van der; Verdonschot, Ralf C.M. ; Kraak, Michiel H.S. ; Verdonschot, Piet F.M. - \ 2018
    Limnologica 72 (2018). - ISSN 0075-9511 - p. 28 - 31.
    Dissolved oxygen saturation - Ecosystem functioning - Monitoring - Primary production - Respiration - Water quality

    The impact of eutrophication on the functioning of drainage ditch ecosystems is understudied. Therefore, we performed a field study to quantify the dissolved oxygen dynamics of ditches at different depths and seasons along a eutrophication gradient. During summer, a clear distinction in daily variation in dissolved oxygen saturation of the top water layer was observed between the trophic states. We recommend including dissolved oxygen dynamics as a functional parameter in drainage ditch monitoring programmes.

    Nationwide screening of surface water toxicity to algae
    Baat, M.L. de; Bas, D.A. ; Beusekom, S.A.M. van; Droge, S.T.J. ; Meer, F. van der; Vries, M. de; Verdonschot, P.F.M. ; Kraak, M.H.S. - \ 2018
    Science of the Total Environment 645 (2018). - ISSN 0048-9697 - p. 780 - 787.
    Algal toxicity - Herbicide risk - Nationwide screening - Pulse amplitude modulation fluorometry - Surface water

    According to the European Water Framework Directive (WFD), chemical water quality is assessed by monitoring 45 priority substances. However, observed toxic effects can often not be attributed to these priority substances, and therefore there is an urgent need for an effect-based monitoring strategy that employs bioassays to identify environmental risk. Algal photosynthesis is a sensitive process that can be applied to identify the presence of hazardous herbicides in surface water. Therefore, the aim of this study was to employ an algal photosynthesis bioassay to assess surface water toxicity to algae and to identify the compounds causing the observed effects. To this purpose, Raphidocelis subcapitata was exposed to surface water samples and after 4.5 h photosynthetic efficiency was determined using PAM fluorometry. In this rapid high throughput bioassay, algal photosynthesis was affected by surface water from only one of 39 locations. Single compounds toxicity confirmation elucidated that the observed effect could be solely attributed to the herbicide linuron, which occurred at 110 times the EQS concentration and which is not included in the WFD priority substances list. In conclusion, applying the algal photosynthesis bioassay enables more efficient and effective assessment of toxicity to primary producers because it: (i) identifies the presence of herbicides that would be overlooked by routine chemical WFD monitoring, and (ii) avoids redundant chemical analyses by focusing only on (non-)target screening in samples with demonstrated effects.

    Sediment composition mediated land use effects on lowland streams ecosystems
    Reis Oliveira, Paula C. dos; Kraak, Michiel H.S. ; Geest, Harm G. van der; Naranjo, Sofia ; Verdonschot, Piet F.M. - \ 2018
    Science of the Total Environment 631-632 (2018). - ISSN 0048-9697 - p. 459 - 468.
    C/N ratio - Deposition zone - Food quality - Macroinvertebrates - Runoff - Sediment respiration
    Despite the widely acknowledged connection between terrestrial and aquatic ecosystems, the contribution of runoff to the sediment composition in lowland stream deposition zones and the subsequent effects on benthic invertebrates remain poorly understood. The aim of this study was therefore to investigate the mechanisms by which runoff affects sediment composition and macroinvertebrates in deposition zones of lowland stream ecosystems. To this end, sediment from runoff and adjacent instream deposition zones from streams with different land use was chemically characterized and the biological effects were assessed at the species, community and ecosystem level. Runoff and deposition zone sediment composition as well as biological responses differed clearly between forest and agricultural streams. The stream deposition zone sediment C/N ratio reflected the respective runoff sediment composition. Deposition zones in the forest stream had a higher C/N ratio in comparison to the agricultural streams. Growth of Hyalella azteca and reproduction of Asellus aquaticus were higher on forest stream sediment, whereas chironomids and worms suffered less mortality on the agricultural sediments containing only natural food. The forest stream deposition zones showed higher values for indices indicative of biological integrity and had a lower sediment oxygen demand. We concluded that agricultural land use affects lowland stream ecosystem deposition zones at the species, community and ecosystem level via altered food quality (C/N ratio) and higher oxygen demand of the sediment.
    Toxicity of sediment-bound lufenuron to benthic arthropods in laboratory bioassays
    Brock, T.C.M. ; Belgers, J.D.M. ; Boerwinkel, M.C. ; Jollie, L. ; Kraak, M.H.S. ; Papo, M.J. ; Vonk, J.A. ; Roessink, I. - \ 2018
    Aquatic Toxicology 198 (2018). - ISSN 0166-445X - p. 118 - 128.
    Benthic macroinvertebrates - Benzoylurea insecticide - Regulatory acceptable concentration - Sediment ecotoxicology - Sediment-spiked laboratory toxicity tests - Species sensitivity distributions
    This paper deals with species sensitivity distributions (SSDs) for the lipophilic insecticide lufenuron and benthic arthropods based on sediment-spiked laboratory toxicity tests. This compound that inhibits chitin synthesis and moulting of arthropods persists in sediment. Using field-collected sediment, toxicity tests were conducted with three macro-crustaceans and six insects. The Hazardous Concentration to 5% of the tested species, the HC5 (and 95% confidence limit), derived from an SSD constructed with 10d-LC50′s was 2.2 (1.2–5.7) μg/g organic carbon (OC) in dry sediment. In addition, HC5 values derived from SSDs constructed with 28d-LC10 and 28-d LC50 values were 0.13 (0.02–1.50) μg/g OC and 2.0 (1.3–5.5) μg/g OC, respectively. In 28d toxicity tests with Chironomus riparius and Hyalella azteca, a higher sensitivity was observed when using lufenuron-spiked field-collected sediment than in lufenuron-spiked artificial sediment. Overall, the non-biting midge C. riparius appeared to be a representative and sensitive standard test species to assess effects of lufenuron exposure in sediment. The Tier-1 (based on standard test species), Tier-2 (based on standard and additional test species) and Tier-3 (model ecosystem approach) regulatory acceptable concentrations (RACs) for sediment-spiked lufenuron did not differ substantially. The Tier-2 RAC was the lowest. Since to our knowledge this study is the first in the open literature that evaluates the tiered approach in the sediment effect assessment procedure for pesticides, we advocate that similar evaluations should be conducted for pesticides that differ in toxic mode-of-action.
    Benthic invertebrate bioturbation activity determines species specific sensitivity to sediment contamination
    Meer, Tom V. van der; Baat, Milo L. de; Verdonschot, Piet F.M. ; Kraak, Michiel H.S. - \ 2017
    Frontiers in Environmental Science 5 (2017)DEC. - ISSN 2296-665X
    Benthic invertebrates - Bioturbation - Sediment contamination - Species specific sensitivity - SSD
    Bioturbation activity of sediment-dwelling organisms promotes the release of contaminants across the benthic-pelagic ecosystem boundary, thereby affecting the exposure to and uptake of sediment associated contaminants at the sediment-water interface by themselves and the entire community around them. This way, bioturbation activity may contribute to species specific sensitivities to sediment associated compounds. Therefore we assessed, based on literature data, if invertebrate bioturbation activity determines species specific sensitivities to sediment contamination. For two metals, Ni and Cu, sufficient data were available to construct Species Sensitivity Distributions (SSD). The position of the species in the SSDs could indeed be linked to their bioturbation rate: the most active bioturbators being the most sensitive benthic invertebrates. Active bioturbators thus enhance their exposure and therewith their sensitivity to sediment associated toxicants. Moreover, active bioturbators can hence promote the release of sediment-associated contaminants across the benthic-pelagic ecosystem boundary, thereby stimulating delivery of contaminants from what is often the most polluted environmental compartment in freshwater ecosystems. It is concluded that trait based ecotoxicology offers a possibly potent tool for predicting sensitivity of benthic invertebrates and the benthic community to sediment-associated contaminants.
    Oxygen drives benthic-pelagic decomposition pathways in shallow wetlands
    Lee, Gea H. Van Der; Kraak, Michiel H.S. ; Verdonschot, Ralf C.M. ; Vonk, J.A. ; Verdonschot, Piet F.M. - \ 2017
    Scientific Reports 7 (2017)1. - ISSN 2045-2322
    Oxygen availability is perceived as an important environmental factor limiting POM decomposition. In shallow wetlands, however, the impact of commonly observed anoxic conditions in the benthic layer on the relative contribution of microbes and invertebrates to POM decomposition remains largely unknown. Therefore, the aim of this study was to determine if dissolved oxygen drives benthic-pelagic decomposition pathways in shallow wetlands. Dissolved oxygen concentration, invertebrate community composition, microbial decomposition and invertebrate consumption were measured in the benthic and pelagic layer of 15 permanent drainage ditches. We showed that an increased duration of anoxic conditions in the benthic layer of the ditches was related to increased microbial decomposition in this layer, while invertebrate consumption decreased in the benthic layer and increased in the pelagic layer. The increased invertebrate consumption in the pelagic layer was related to the presence of amphipods. We concluded that anoxic conditions in the benthic layer of shallow wetlands relate to an increase in microbial decomposition and a decrease in invertebrate consumption, as detritivorous invertebrates move to the pelagic layer to consume particulate organic matter. This illustrates that environmental conditions, such as dissolved oxygen, may drive the relative importance of aquatic organisms to ecosystem functioning.
    Flow velocity tolerance of lowland stream caddisfly larvae (Trichoptera)
    Brouwer, J.H.F. de; Besse-Lototskaya, A.A. ; Braak, C.J.F. Ter; Kraak, M.H.S. ; Verdonschot, P.F.M. - \ 2017
    Aquatic Sciences 79 (2017)3. - ISSN 1015-1621 - p. 419 - 425.
    Drift - Flow velocity - Lowland streams - Return rates - Trichoptera
    The process of macroinvertebrate drift in streams is characterized by dislodgement, drift distance and subsequent return to the bottom. While dislodgement is well studied, the fate of drifting organisms is poorly understood, especially concerning Trichoptera. Therefore, the aim of the present study was to determine the ability of six case-building Trichoptera species to return to the stream bottom under different flow velocity conditions in a laboratory flume. The selected species occur in North-West European sandy lowland streams along a gradient from lentic to lotic environments. We determined species specific probability curves for both living and dead (control) specimens to return to the bottom from drift at different flow velocities and established species specific return rates. Species on the lotic end of the gradient had highest return rates at high flow velocity and used active behaviour most efficiently to return to the bottom from drift. The observed gradient of flow velocity tolerance and species specific abilities to settle from drift indicate that, in addition to dislodgement, the process of returning to the bottom is of equal importance in determining flow velocity tolerance of Trichoptera species.
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