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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    We will mail you new results for this query: wurpublikatie/titelbeschrijving/classificatie/trefwoord/cab/engels==aquatic ecology
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Benthic development around a gas platform in the North Sea -: a small scale closure for fisheries : a trait based approach
Glorius, Sander ; Hal, Ralf van; Kaag, Klaas ; Weide, Babeth van der; Chen, Chun ; Kooten, Tobias van - \ 2016
Den Helder : Wageningen Marine Research (Wageningen Marine Research rapport ) - 42
benthos - aquatic communities - aquatic ecology - fisheries - north sea - aquatische gemeenschappen - aquatische ecologie - visserij - noordzee
This project looked at the effect of closing an area for fisheries on the development of the benthic community. An existing data set of benthic species densities sampled at different distances and angles from a platform was used for this purpose. The particular area was closed due to the installation of a gas production platform, but is likely to function as a marine protected area (MPA), with the expectation that the benthic community develops differently from the benthic community in the surrounding areas as it no longer has to cope with the impact of fisheries. Differences in development might be linked to the impact of fisheries and the effects of closure might provide an expectation for the effect of planned MPAs in similar areas.
Pulse fishing and its effects on the marine ecosystem fisheries : an update of the scientific knowledge
Rijnsdorp, Adriaan ; Haan, Dick de; Smith, Sarah ; Strietman, Wouter Jan - \ 2016
IJmuiden : Wageningen Marine Research (Wageningen Marine Research report C117/16) - 30
pulse trawling - fishing methods - fisheries - aquatic ecology - marine ecology - aquatic ecosystems - pulsvisserij - vismethoden - visserij - aquatische ecologie - mariene ecologie - aquatische ecosystemen
This report summarises the knowledge on the effects of pulse trawls used in the North Sea fishery for flatfish and brown shrimp. The report describes the electrical characteristics of the pulse trawl systems currently used (potential difference over electrode pairs, pulse frequency, pulse width, duty cycle and dimensions of the gear). The shrimp pulse applies a low frequency pulse that invokes a startle response (tailflip) in shrimps. The sole pulse applies a higher frequency that invokes a cramp response that immobilise the fish species facilitating the catching process.
Aquatisch ecoloog Piet Verdonschot wil kennis biologen beter inzetten voor herstelmaatregelen "verbind wetenschap en waterschap"
Verdonschot, Piet - \ 2016
aquatic ecology - ecological restoration - flora - fauna - monitoring - scientific research

Herstelmaatregelen om waterkwaliteit te verbeteren zijn maar weinig effectief. In zijn oratie tot bijzonder hoogleraar herstelecologie geeft Piet Verdonschot uitleg.

The ecology of ditches : a modeling perspective
Gerven, Luuk P.A. - \ 2016
University. Promotor(en): W.M. Mooij, co-promotor(en): Jeroen de Klein; J.H. Janse. - Wageningen : Wageningen University - ISBN 9789462579316 - 137
ditches - aquatic ecology - ecology - modeling - aquatic plants - aquatic ecosystems - water flow - sloten - aquatische ecologie - ecologie - modelleren - waterplanten - aquatische ecosystemen - waterstroming

The Netherlands is well-known for its extended networks of drainage ditches, with a total ditch length of about 300.000 km. Their main function is to enable agriculture by draining water. Nonetheless, ditches also have important ecological functions. They serve as ecological corridors and harbor a high biodiversity in which water plants play a crucial role. The last decades, the ecological quality of ditches is at stake. Enhanced nutrient inputs promoted the invasion by dense mats of free-floating plants like duckweed. Underneath these mats the water becomes dark and anoxic, which severely constrains aquatic life.

In this thesis I developed new concepts to better understand, predict and combat the dominance by free-floating plants in ditches. The following questions are addressed. Are floating plants a self-stabilizing state - an alternative stable state - which would make it more difficult to combat floating-plant dominance (chapter 2)? Does it make sense to fight floating-plant dominance by reducing nitrogen (N) inputs to the ditches or will it lead to an invasion of floating plants that can fix N2 from the atmosphere (chapter 3)? What about spatial aspects, does the vulnerability of a ditch to floating plants depend on the position of a ditch in a polder, like its distance to the polder outlet (chapter 4)? To answer these questions, I used ecological models that predict the abundance of free-floating plants based on the competition for nutrients and light with other plants such as submerged plants, and where possible validated these models with field data. Starting from the ecosystem model PCDitch, I developed and combined models with different complexity to see how theoretical concepts, developed in minimal models, translate to the ecosystem level. Chapter 5 deals with a method that facilitates this up- and downscaling in model complexity.

Are floating plants an alternative stable state? To answer this question I extended mechanistic resource competition theory with a framework (minimal model) describing the competition of floating and submerged plants for light and nutrients. The model predicts that the competitive advantage of floating plants - they have a primacy for light and shade submerged plants, giving rise to asymmetry in competition for light - makes that floating plants always dominate at high supply of light and nutrients. At intermediate nutrient supply, there can be alternative stable states: either the submerged plants or the floating plants dominate depending on who established first. However, based on the traits of common floating plants (duckweed; Lemna) and submerged plants (waterweed; Elodea) the model predicts, in line with field data, that floating plants are not an alternative stable state. Furthermore, from a theoretical point of view this study shows that the asymmetry in light competition ensures that common rules from standard competition theory do not apply anymore. Like the R* rule, which states that the species that can persist at the lowest resource levels always wins the competition.

Can duckweed-dominance be combatted by reducing N inputs to the ditches? Or does this promote other floating plants like water fern (Azolla) that can fix N2 from the atmosphere? Important is the question whether such N2-fixers can provide enough N to prevent N-limitation and keep the system P-limited, which would make steering on N inputs ineffective. To investigate this, I considered the competition between Lemna and Azolla for N, P and light. Both a minimal model, an ecosystem model (PCDitch) and field data reveal that N2-fixation is unlikely to lead to P-limitation. This can be explained by N2-fixers typically requiring higher P concentrations to persist, implying that they cannot keep the P concentration low enough for non-N2-fixers to become P-limited. In combination with field data that hint at constraints on N2-fixation that prevent N2-fixers from becoming abundant at low N availability, this suggests that it certainly pays off to combat floating plant-dominance by reducing N inputs.

Is every ditch in a polder equally vulnerable to floating plants? Each ditch in a polder receives water and nutrients from the adjacent land. This leads to a spatial gradient in water flow and associated nutrient loading, from low in the remote polder sites to high in the direction of the polder outlet where the water leaves the polder. I explored if this spatial gradient affects the vulnerability of a ditch to floating plants, by investigating with a simple nutrient model how this gradient affects the nutrient concentration of the ditches and by subsequently predicting the gradient's effect on the ditch ecology by applying the ecosystem model PCDitch spatially, through coupling PCDitch to the 1-D hydrodynamic model SOBEK. Surprisingly, we found that every ditch is equally vulnerable to floating plants, despite the spatial gradient in water flow and nutrient loading. It turned out that the ecological state of each ditch could already be predicted by regarding only the lateral supply of water and nutrients from the adjacent land, and not the supply from upstream ditches. However, these findings are violated when there is spatial heterogeneity in the water and nutrient supply from the adjacent land or in ditch characteristics like depth and sediment type. Then, the chance on floating-plant dominance differs throughout the network and a spatial modelling approach (PCDitch-SOBEK) is required to predict this chance.

Developing and combining models of different complexity plays an important role in this thesis. To do so, I used a Database Approach To Modelling (DATM), a recently developed method in which a model is stored in tables in a clear and clean way, which facilitates model development. In addition, with DATM a model can be automatically implemented in a modelling environment of choice. This relieves technical implementation issues and leaves room to focus on ecology rather than technology. I illustrated the use of DATM by implementing and analyzing the ecosystem model PCDitch and its twin model for shallow lakes PCLake in different modelling environments by using DATM. This showed that DATM allows one to use the environment one is familiar with and eases the switch to other environments for complementary analyses, including analysis in a spatial 1-D to 3-D setting.

The insights provided by this thesis can help us to improve the ecological quality of ditches. A challenging task, given the fast human-driven environmental changes at both local and global level. To predict and to anticipate the effect of these changes on the ecology, it is essential to understand how the ditch ecosystem functions. The developed and applied methods described in this thesis may be helpful in that. For example, using models of different complexity makes it possible to translate fundamental theory to the ecosystem scale, which is essential to better grasp the behavior of an ecosystem. Furthermore, the in this thesis established coupling between PCDitch and SOBEK breaks new grounds for spatial ecosystem modelling. In combination with the growing amount of remote sensing data from satellites and drones, which allow for the continuous and potentially real-time validation and calibration of spatial ecosystem models, such a spatial approach has the potential to greatly increase our ecological understanding of ditches. These advances facilitate the development of successful management strategies that make our ditch ecosystems future-proof.

Making eco logic and models work : an integrative approach to lake ecosystem modelling
Kuiper, Jan Jurjen - \ 2016
University. Promotor(en): W.M. Mooij, co-promotor(en): J.H. Janse; Jeroen de Klein. - Wageningen : Wageningen University - ISBN 9789462579446 - 192
ecology - models - ecosystems - modeling - aquatic ecology - water management - water quality - databases - ecologie - modellen - ecosystemen - modelleren - aquatische ecologie - waterbeheer - waterkwaliteit - databanken

Dynamical ecosystem models are important tools that can help ecologists understand complex systems, and turn understanding into predictions of how these systems respond to external changes. This thesis revolves around PCLake, an integrated ecosystem model of shallow lakes that is used by both scientists and water quality managers to understand and predict eutrophication effects in shallow lake ecosystems. Shallow lakes provide some of the clearest examples of alternative stable states in natural systems. PCLake can be used to calculate the critical nutrient loading, that is, the nutrient loading where an abrupt regime shift occurs from a clear aquatic plant dominated state to a turbid phytoplankton dominated state, or vice versa. Four different aspects of modelling with PCLake are addressed in this thesis: (1) making the model better accessible for the modelling community, (2) improving the model, (3) developing scientific theory, and (4) exploring new applications for water quality management.

Following a general introduction to the thesis in chapter 1, the Database Approach To Modelling (DATM) is introduced in chapter 2. DATM is invented to make dynamic models more accessible. The idea of DATM is that the mathematical equations of a model are stored in a database independently of program language and software specific information. From the database, the information can be automatically translated, augmented and compiled into working model code of various different modelling frameworks (software programs).

In chapter 3 the weak link between ecosystem models and real ecosystems is discussed in relation to model calibration and improvement. In a previous stage PCLake has been calibrated using data of more than 40 lakes to obtain a best overall fit, which has greatly increased the scope of the model by making it suitable for more generalized studies on temperate shallow lakes. However, because of this calibration, adding missing functional components to the model at a later stage does not automatically increase the validity of the model, as it may bring the model ‘out of balance’. This is exemplified by adding filter feeding zoobenthos to PCLake, which were previously ignored.

In chapter 4, the relation between food-web theory and alternative stable states theory is scrutinized. Both theoretical paradigms are highly influential in modern ecology as they help scientists understand how stability emerges in complex natural ecosystems. Unfortunately, they developed independently and it is largely unclear how the resilience of a food web relates to the stability of the complete ecosystem. For this study PCLake was used as a virtual reality from which ‘empirical’ information is sampled to parameterize a food web model, following traditional food web methods. This allowed calculating the stability of the food web along a gradient of environmental change, knowing that the complete ecosystem shows a regime shift once the critical nutrient loading is exceeded.

In chapter 5 the question is asked to what extent models of a different form can be used to describe the same natural phenomenon, and hence, how these models can be used for a better understanding of such natural phenomena. Using three classical extensions of the famous Lotka-Volterra equations, which unlike PCLake can be fully mathematically understood, we analyze the consequence of changing a system with a sophisticated functional response term (e.g. Holling type II or III) into a system with a simpler functional response term while maintaining equilibrium densities and material fluxes. These results give new insight into when empirical data can be linked to mathematical models to estimate the stability properties of real ecosystems.

Although PCLake is predominantly applied in the context of ecosystem restoration of turbid phytoplankton dominated lakes, chapter 6 focusses on the clear water state after the reestablishment of aquatic plant dominance as occured. Dense stands of aquatic plants easily cause nuisance, and hence the removal of aquatic plants is an emerging management issue. Yet, because aquatic plants play an important role in stabilizing the clear water state, the removal of plant biomass can potentially trigger a critical transition back to the turbid water state. Currently there is only limited empirical and theoretical understanding of how harvesting of aquatic plants affects ecosystem functioning, which frustrates effective and efficient ecosystem management. With PCLake the impact of harvesting is evaluated, in terms of reducing nuisance and ecosystem stability, for a wide range of external nutrient loadings, mowing intensities and timings. Additionally, the model is used to estimate how much phosphorus is removed from the system during harvesting.

In chapter 7 I discuss the added value of taking an integrative approach to modelling, and discuss the integrated nature of the studies presented in this thesis. It’s also important to note that these studies were part of a larger research project with the overall aim of increasing the usefulness and the validity of PCLake and its twin model PCDitch, and to enhance the confidence in the models among water quality managers. A synopsis of the overarching collaborative research project on PCLake and PCDitch is presented in chapter 8.

'Met goede monitoring verdien je je geld dubbel en dwars terug'
Mooij, Wolf ; Verdonschot, Piet - \ 2016
water quality - monitoring - water management - aquatic ecology - water systems

Drie dagen congresseren over waterkwaliteitsmonitoring. Je moet wel lef hebben, vond Inge Diepman, dagvoorzitter van de eerste dag van het driedaagse STOWA-congres ‘Goede monitoring, effectief waterkwaliteitsbeheer’, dat plaatsvond op 19, 20 en 21 april 2016 in Arnhem. Want valt er over monitoring wel zoveel te zeggen, en hoe belangrijk is het eigenlijk? Heel belangrijk, zo bleek tijdens het congres. Daarom staan we er in deze editie van de STOWA ter Info nog een keer uitgebreid bij stil.

Invloed van beekbegeleidende bomen op de ecologische kwaliteit van Noord-Brabantse beken
Verdonschot, R.C.M. ; Brugmans, Bart ; Scheepens, Mark ; Coenen, Daniël ; Verdonschot, P.F.M. - \ 2016
H2O online (2016)28 juli.
aquatische ecologie - waterlopen - bomen - noord-brabant - monitoring - beschaduwen - gegevensanalyse - waterschappen - vegetatie - waterplanten - waterkwaliteit - aquatic ecology - streams - trees - shading - data analysis - polder boards - vegetation - aquatic plants - water quality
Monitoringsdata van Brabantse beken laat zien dat bomen belangrijk zijn voor het halen van ecologische doelen. Echter, voor maximale effectiviteit met betrekking tot vegetatieontwikkeling en koeling van het beekwater voldoet alleen de zwaarste beschaduwingsklasse (>70%) en moet gestreefd worden naar lange beschaduwde trajecten. Macrofauna profiteert vooral via de door bomen gegenereerde substraatdifferentiatie. Het toepassen van beschaduwing brengt voor de waterschappen wel grote uitdagingen met zich mee. Verder blijkt uit de data-analyse dat jaarrond voldoende stroming een vereiste is voor de ecologische doelrealisatie in de trajecten.
The neurotoxin BMAA in aquatic systems : analysis, occurrence and effects
Faassen, E.J. - \ 2016
University. Promotor(en): Marten Scheffer, co-promotor(en): Miguel Lurling. - Wageningen : Wageningen University - ISBN 9789462577855 - 194 p.
cum laude - neurotoxins - aquatic environment - urban areas - effects - environmental impact - daphnia magna - elisa - water quality - analytical methods - aquatic ecology - neurotoxinen - aquatisch milieu - stedelijke gebieden - effecten - milieueffect - waterkwaliteit - analytische methoden - aquatische ecologie

Eutrophication is a major water quality issue and in many aquatic systems, it leads to the proliferation of toxic phytoplankton species. The neurotoxin β-N-methylamino-L-alanine (BMAA) is one of the compounds that can be present in phytoplankton. BMAA has been suggested to play a role in the neurodegenerative diseases Alzheimer’s disease, Parkinson’s disease and amyotrophic lateral sclerosis, although this hypothesis still needs to be confirmed. It is expected that the main human exposure pathways to BMAA are through direct contact with BMAA containing phytoplankton and through ingestion of BMAA contaminated food, such as fish and shellfish. However, reports on the occurrence of BMAA in aquatic systems have been conflicting and the cause of these reported differences was heavily debated. The use of different analytical methods seems to play a crucial role in the observed discrepancies, but initially, there was little consensus on which method produced most reliable results. The objectives of the work presented in this thesis therefore were to find out what has caused the differences in published results on BMAA concentrations, and to identify and produce reliable data on the presence of BMAA in aquatic systems. In addition, I aimed to determine the effect of BMAA exposure on a key species in many freshwater ecosystems, the grazer Daphnia magna.

The performances of different analytical techniques were compared, and LC-MS/MS analysis, either preceded by derivatisation or not, was found to produce most reliable results. LC-FLD and ELISA should not be used for BMAA analysis, as both methods risk misidentifying BMAA or overestimating its concentrations due to their low selectivity. When reviewing literature on the presence of BMAA in aquatic systems, it was found that the observed discrepancies in results could be explained by the use of unselective analytical methods in some studies, and by severe reporting deficiencies in others. When only studies that used appropriate analytical techniques and that correctly reported their work were taken into account, it was shown that BMAA could be present in phytoplankton and higher aquatic organisms, in concentrations of µg/g dry weight or lower. These results are in agreement with our findings of BMAA in cyanobacterial scums from Dutch urban waters. In a 2008 screening, BMAA was found to be present in 9 out of 21 analysed cyanobacterial scums, at concentrations ranging from 4 to 42 µg/g dry weight. When this screening was repeated 8 years later with 52 similar samples, BMAA was detected below the quantification limit in one sample and quantified in another sample at 0.6 µg/g dry weight.

In order to perform the work presented in this thesis, sensitive and selective analytical methods, mostly based on LC-MS/MS analysis without derivatisation, were developed. This resulted in a standard operating procedure for the underivatised LC-MS/MS analysis of BMAA in cyanobacteria. Also, a CYANOCOST initiated workshop was given, in which a group of scientists from 17 independent laboratories evaluated LC-MS/MS based methods in different matrices. A bound BMAA from found in the supernatant was the most abundant fraction in the positive samples that were tested: cycad seed, seafood and exposed D. magna. In addition, it was found that the deuterated internal standard used for quantification was not a good indicator for the release of BMAA from bound forms, resulting in unprecise quantification of total BMAA.

BMAA was found to reduce survival, somatic growth, reproduction and population growth in D. magna. Animals did not adapt to BMAA exposure: exposed animals born from exposed mothers had a lower brood viability and neonate weight than animals exposed to BMAA, but born from unexposed mothers. In addition, D. magna was shown to take up BMAA from the growth medium and to transfer it to its offspring. D. magna therefore might be an important vector for BMAA transfer along the pelagic food chain, but whether BMAA plays a role in preventing zooplankton from controlling cyanobacterial blooms needs further investigation.

Although BMAA research has much progressed between the start of this thesis’ work and its completion, some important questions still require an answer. Most urgently, it should be determined whether BMAA is indeed involved in the neurological diseases mentioned above, and if so, which doses trigger the onset of these diseases. Human exposure pathways should then be more systematically quantified, and it might be prudent to investigate if the occurrence of BMAA is restricted to aquatic systems, or whether sources from terrestrial systems contribute to BMAA exposure as well.

Ecologische kantelpunten in de Nederlandse grote wateren : Discussie memo over recente inzichten, voorbeelden en onderzoeksvragen
Veraart, J.A. ; Reijers, Valerie ; Lange, H.J. de; Nes, E.H. van; Kosten, S. ; Baptist, M.J. ; Noordhuis, Ruurd ; Platteeuw, M. - \ 2016
- 33 p.
aquatische ecologie - watersystemen - waterbeheer - waterkwaliteit - aquatische ecosystemen - aquatic ecology - water systems - water management - water quality - aquatic ecosystems
Deze memo beschrijft recente inzichten op het terrein van ecologische kantelpunten die zijn opgedaan in onderzoek en bij Rijkswaterstaat. Gegeven de korte projectduur (twee maanden) is er niet gestreefd naar volledigheid, maar zijn er inzichten bijeengebracht die behulpzaam zijn om de discussie aan te zwengelen over wat de kantelpuntentheorie kan betekenen voor het beheer, evaluatie en monitoring van de grote wateren. In het sterk gemodificeerde Nederlandse watersysteem is het moeilijk om vast te stellen of alternatieve evenwichten onder gelijke condities mogelijk zijn en dat kantelpunten hiertussen plaatsvinden. Alternatieve evenwichten en terugkoppelingsmechanismen zijn het best onderbouwd en omschreven in de literatuur voor de Waddenzee en Veluwemeer. In de estuaria zijn er veel indicaties maar ook veel onzekerheden. In het rivierengebied is het de vraag of alternatieve evenwichten kunnen bestaan. Het beter begrijpen van terugkoppelingsmechanismen in de Nederlandse zoete en zoute wateren, en de interacties hiertussen, wordt echter breed onderschreven. Terugkoppelingsmechanismen
zijn met het kantelpuntenconcept goed te onderzoeken voor alle watersystemen en een beter begrip hierover is nuttig voor beleidsevaluaties, het inschatten van het effect van ecologische ingrepen en monitoringsplannen. Het is belangrijk om ook rekening te houden met ‘onbekende’ en niet kwantificeerbare factoren die de veerkracht van een ecosysteem kunnen beïnvloeden. Er is nog niet veel bekend over de invloed van microverontreinigingen, trofische cascades (vissen, vogels), microbiële bodemactiviteit en de rol van hydromorfologische dynamiek in rivieren en estuaria op de ecologische veerkracht van een watersysteem. Het is aan te bevelen om eerst met een aantal casestudies te
verkennen wat de mogelijkheden en datavereisten zijn om met langjarige tijdreeksen (ecologie, waterkwaliteit) indicatoren te bepalen die iets zeggen over verandering in ecologische veerkracht. Voorts doen wij de aanbeveling om het begrip ' Safe operating Space’ beter hanteerbaar te maken voor wateren natuurbeheerders.
Environmental risk assessment of pesticides in Ethiopia : a case of surface water systems
Teklu, B.M. - \ 2016
University. Promotor(en): Paul van den Brink. - Wageningen : Wageningen University - ISBN 9789462578104 - 152 p.
surface water - water systems - water pollution - risk assessment - ecological risk assessment - pesticides - aquatic ecology - aquatic organisms - irrigation systems - ethiopia - oppervlaktewater - watersystemen - waterverontreiniging - risicoschatting - ecologische risicoschatting - pesticiden - aquatische ecologie - waterorganismen - irrigatiesystemen - ethiopië

The current increase in application rate and usage frequency of application of pesticides in Ethiopia pose direct risks to surface water aquatic organisms and humans and cattle using surface water as a source of drinking water in rural parts of the country. A model based risk assessment as currently being used in Europe and elsewhere in the world is tailored to the Ethiopian situation to quantify the risks. Suitability of toxicity data used as an input for risk assessment usually taken from the temperate world was checked through simple toxicity testing of Ethiopian aquatic macroinvertebrates. Subsequent monitoring activities to see the actual residue levels of pesticides in rivers and temporary ponds adjacent to extensive farming activities was also done and results compared with model prediction values. Combining all this knowledge is believed to bring the current pesticide registration system in Ethiopia one step closer to be a more reliable method, protecting non-target organisms as well as the health of humans at risk.

Simplifying complexity : reflections on ecosystems, psychiatric disorders and biogeochemical pathways
Leemput, I.A. van de - \ 2016
University. Promotor(en): Marten Scheffer; Egbert van Nes. - Wageningen : Wageningen University - ISBN 9789462577930 - 211 p.
ecosystems - models - biogeochemistry - nitrogen - coral reefs - climate - aquatic ecology - ecosystemen - modellen - biogeochemie - stikstof - koraalriffen - klimaat - aquatische ecologie
Vissen in de nieuw aangelegde hoogwatergeul in de Raaijweide bij Venlo
Pollux, B.J.A. ; Korosi, A. ; Nagelkerke, L.A.J. ; Pollux, P.M.J. - \ 2016
Natuurhistorisch Maandblad 105 (2016)5. - ISSN 0028-1107 - p. 100 - 106.
nature development - river forelands - channels - fish fauna - natural areas - limburg - flood control - aquatic ecology - fishes - natuurontwikkeling - uiterwaarden - kanalen, klein - visfauna - natuurgebieden - hoogwaterbeheersing - aquatische ecologie - vissen
De afgelopen decennia is er in toenemende mate aandacht gekomen voor natuurontwikkeling in rivieruiterwaarden. Een belangrijk onderdeel hiervan vormt het graven van hoogwatergeulen: korte nevenlopen die (bij hoogwater) parallel aan de hoofdstroom met de rivier meestromen en die gedurende de rest van het jaar ook water houden. Zulke geulen worden vaak gekenmerkt door een lagere stroomsnelheid dan de rivier zelf, gevarieerde oevers met ondiepe zandbanken en een rijke oever- en onderwatervegetatie. In dit artikel wordt de visfauna beschreven in een recent aangelegde hoogwatergeul in natuurgebied de Raaijweide bij Venlo.
Vangst- en inspanningsadviezen over snoekbaars, baars, blankvoorn en brasem in het IJssel-/Markermeer: visseizoen 2016/2017
Tien, N.S.H. ; Hammen, T. van der - \ 2016
IMARES (Rapport / IMARES C019/16) - 75 p.
visstand - vissen - aquatische ecologie - visserijbeleid - natuurbeheer - ijsselmeer - visvangsten - fish stocks - fishes - aquatic ecology - fishery policy - nature management - lake ijssel - fish catches
Het Ministerie van Economische Zaken (EZ) wil komen tot wetenschappelijk onderbouwd duurzaam beheer van snoekbaars, baars, blankvoorn en brasem in het IJsselmeer en Markermeer. Voor alle vier bestanden is de beleidsdoelstelling voor visseizoen 2016/2017 geformuleerd als “een zekere mate van herstel”. Voor het behalen van deze beleidsdoelstelling zijn inspanningsadviezen gevraagd over de staandwantvisserij en de zegenvisserij, gecombineerd voor het IJsselmeer en Markermeer. Dit rapport bevat een primair en, op verzoek van de opdrachtgever, een alternatief advies. Het primaire advies is beschreven in hoofdstuk 1, het alternatieve advies is uitgewerkt in hoofdstukken 2 tot en met 8. Deze adviezen hebben als doelstelling het voorkomen van verdere achtergang van de visbestanden. Voor de doelstelling ‘een zekere mate van herstel’ worden aanvullende adviezen gegeven. Alle drie adviezen zijn samengebracht in hoofdstuk 9.
Achtergronddocument t.b.v. de uitgave Wadden in Beeld 2015
Tulp, I.Y.M. ; Cremer, J.S.M. ; Troost, K. ; Glorius, S.T. ; Asjes, J. - \ 2016
IMARES (Rapport / IMARES C018/16) - 26 p.
zeevissen - mossels - oesters - zeehonden - kokkels - aquatische wormen - aquatische ecologie - waddenzee - marine fishes - mussels - oysters - seals - clams - aquatic worms - aquatic ecology - wadden sea
Towards monitoring zoöplankton and small pelagic fish in the Wadden Sea
Couperus, A.S. ; Jak, R.G. ; Flores, H. ; Gastauer, S. ; Fassler, S.M.M. - \ 2016
IJmuiden : IMARES (Report / IMARES C094/13) - 56 p.
zooplankton - fishes - monitoring - acoustics - wadden sea - aquatic ecology - netherlands - zoöplankton - vissen - geluidsleer - waddenzee - aquatische ecologie - nederland
Ecotopenkaart voor het Eems-Dollard estuarium
Ysebaert, T. ; Wal, J.T. van der; Tangelder, M. ; Groot, A.V. de; Baptist, M.J. - \ 2016
Yerseke : IMARES (Rapport / IMARES C059/15) - 48 p.
estuaria - aquatische ecosystemen - habitatbeheer - ecologische beoordeling - aquatische ecologie - eems-dollard - estuaries - aquatic ecosystems - habitat management - ecological assessment - aquatic ecology
Dit rapport geeft een eerste aanzet tot het maken van een actuele ecotopenkaart voor het Eems-Dollard estuarium (NL en D deel, excl. Unterems) volgens de ZES.1 methodiek. Dit is één van de instrumenten die kan worden gebruikt voor het evalueren van mogelijke maatregelen in het MIRT-onderzoek en de mogelijke MIRT-verkenning Eems-Dollard. Daarnaast kan deze dienen als aanzet voor een operationele ecotopenkaart van het Eems-Dollard estuarium voor meer algemene beleidsondersteuning. De methode laat tevens toe een vergelijking te maken met ecotopenkaarten van bijv. de Westerschelde.
Further improvements in water quality of the Dutch Borderlakes : two types of clear states at different nutrient levels
Noordhuis, Ruurd ; Zuidam, B.G. van; Peeters, E.T.H.M. ; Geest, G.J. van - \ 2016
Aquatic Ecology 50 (2016)3. - ISSN 1386-2588 - p. 521 - 539.
Abramis brama - Alternative stable states - Biomanipulation - Cyanobacteria - Dreissena - Macro-algae - Quagga Mussel - Regime shift - randmeren - mussels - algae - water quality - aquatic ecology - eutrophication - abramis brama - mossels - cyanobacteriën - algen - waterkwaliteit - aquatische ecologie - eutrofiëring

The Borderlakes are a chain of ten shallow, largely artificial, interconnected lakes in the Netherlands. The ecological recovery of the central Borderlakes (viz. lake Veluwe and Wolderwijd) has been well documented. These lakes shifted from a eutrophic, Planktothrix dominated state in the 1970s to a clear state in 1996. Around 2010, the formerly hypertrophic, southern Borderlake Eem also reached a clear state, but at considerably higher nutrient levels. In this paper, monitoring data are used to compare these changes and identify the differences in driving processes and their consequences. The 1996 shift in Lake Veluwe was linked to increased fishery for benthivorous Bream, followed and stabilized by increase in Zebra Mussels and charophytes. Nutrients in Lake Eem decreased as well and Planktothrix disappeared here too in 1996, despite relatively high TP concentrations which remained stable over time. The start of the change into the clear state in this case also involved a decrease in the Bream population, but with a stronger additional role for dreissenids, particularly of Quagga Mussels. Remaining blooms of cyanobacteria almost disappeared, but the current situation in Lake Eem represents a different type of clear water state than in the central Borderlakes. This type is characterized by the combination of a relatively high phosphorus load, intense dreissenid filtration and filamentous macro-algae instead of either blooms of cyanobacteria or dominance of charophytes. With the dominant role of the River Eem, the relatively short residence time and increasing difficulty to bring down nutrient loading any further, the stability of this clear state depends on high densities (and filtration rates) of dreissenids.

Een evaluatie van de maatlatten R6 en R7 voor de Kader Richtlijn Water
Griffioen, A.B. ; Vries, I. de - \ 2016
IMARES (Rapport / IMARES C087/15) - 28 p.
rivieren - kaderrichtlijn water - waterbeheer - classificatie - waterkwaliteit - aquatische ecologie - monitoring - rivers - water framework directive - water management - classification - water quality - aquatic ecology
De watertypes R6 en R7 in de Kader Richtlijn Water (KRW) classificering verschillen qua grootte van het waterlichaam en structuur. Het watertype R7 staat voor de grote rivieren met een hoofdstroom en nevengeulen. Rivieren als de Rijn, Waal en IJssel zijn hier voorbeelden van. Het watertype R6 staat voor langzaam stromende kleinere rivieren. In de praktijk kunnen beide riviertypen in elkaar overgaan en is het goed mogelijk dat het visbestand een grote overlap kent, maar volgens verschillende maatlatten worden beoordeeld. Dit onderzoek heeft tot doel het inzichtelijk maken van de indeling in beide watertypes. Ook wordt er gekeken naar de verschillen tussen de watertypen R6 en R7.
Van open riool naar leefbare beek, een flinke stap in de goede richting
Schollema, Peter Paul ; Dongen, M. van; Dam, H. van; Winter, Hendrik V. ; Griffioen, A.B. ; Vroome, A.I. de - \ 2015
De Levende Natuur 116 (2015)3. - ISSN 0024-1520 - p. 104 - 108.
afvoerwater - waterkwaliteit - waterlopen - aquatische ecologie - pesticiden - natuurgebieden - monitoring - ecologisch herstel - drenthe - effluents - water quality - streams - aquatic ecology - pesticides - natural areas - ecological restoration
Een beek in het Noorden van het land waarover in 1941 wordt gemeld dat in de benedenloop meer dan 5000 pond dode vis is afgevoerd en rond 1961 vrijwel alle vis uit het water verdwenen blijkt te zijn. Ook het water waar een monsternemer in 1964 meldt dat de roggebroden tijdens het uitvoeren van de metingen voorbijdreven. Het is erg moeilijk voor te stellen dat we het hier hebben over de Drentsche Aa, één van de meest intacte beeksystemen van Nederland. De beek heeft de laatste eeuw grote veranderingen in waterkwaliteit ondergaan, zowel in positieve als negatieve zin. Welke oorzaken lagen hieraan ten grondslag, hoe reageerde de beekgebonden natuur hierop en wat is er nodig voor verder herstel?
Toestand vis en visserij in de Zoete Rijkswateren: 2014 Deel I: Trends van de visbestanden, vangsten en ecologische kwaliteit ratio's
Graaf, M. de; Boois, I.J. de; Griffioen, A.B. ; Overzee, H.M.J. van; Tien, N.S.H. ; Tulp, I.Y.M. ; Vries, P. de; Deerenberg, C.M. - \ 2015
IMARES (Rapport / IMARES C199/15) - 102 p.
zoet water - aquatische ecologie - vissen - monitoring - rivieren - inventarisaties - visserij - visvangsten - vistuig - ijsselmeer - visstand - fresh water - aquatic ecology - fishes - rivers - inventories - fisheries - fish catches - fishing gear - lake ijssel - fish stocks
Het rapport “Toestand Vis en Visserij in de Zoete Rijkswateren” bestaat uit drie verschillende delen: “Trends”, “Methoden” en “Data”. In dit rapport (Deel I) worden (i) de trends in commercieel benutte vissoorten per VBC gebied, (ii) de trends in Habitatrichtlijnsoorten en (iii) de ecologische kwaliteitsratio’s vis gerapporteerd. Hiervoor is gebruik gemaakt van de gegevens die binnen de verschillende vismonitoringsprogramma’s op de Zoete Rijkswateren worden verzameld. In de rapportage zijn trendanalyses voor de verschillende commercieel benutte vissoorten en Habitatrichtlijn vissoorten gemaakt aan de hand van de beschikbare monitoringsgegevens. De gegevens van deze monitoringsprogramma’s worden gebruikt als indicatoren voor de ontwikkeling van de bestanden van de geanalyseerde soorten over verschillende tijdsperioden.
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