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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Using the ecosystem services concept to analyse stakeholder involvement in wetland management
Cohen-Shacham, E. ; Dayan, T. ; Groot, R.S. de; Beltrame, C. ; Guillet, F. ; Feitelson, E. - \ 2015
Wetlands Ecology and Management 23 (2015)2. - ISSN 0923-4861 - p. 241 - 256.
water management - israel - hula - typology - basin - lake
Wetland management usually involves multiple stakeholders. This paper describes how the use of the ecosystem services (ES) concept can help to identify the main stakeholders associated with wetland conservation, using the Hula Wetland in the Sea of Galilee’s watershed as a case study. We conducted a stakeholder analysis based on semi-structured interviews. We focused on the management of two semi-natural areas within the larger Hula Wetland area (Hula Nature Reserve and Agamon), in which different management regimes are used and which provide different bundles of ES to different stakeholders. Using the ES concept in the stakeholder analysis, we were able to present the Hula Wetland management in a comprehensive manner. The approach also revealed a lack of coordination between the managing organisations which might lead to competition favouring cultural services (in particular tourism) at the expense of habitat services (i.e. biodiversity conservation) in the future. To test our method we also conducted a stakeholder analysis in the Camargue Wetland in France. The two wetlands have similar characteristics but are embedded in different institutional contexts. The Camargue Regional Park has a multi-stakeholder platform which could serve as an example for the Hula Wetland to improve its management and lead to better coordination and complementarity of ES provided by the two sub-sites. Our study showed that applying the ES concept helps to quickly identify relevant stakeholders and analyse wetland management in a more holistic way and to point towards sustainable solutions for conflicting stakeholder interests.
Community stoichiometry in a changing world: combined effects of warming and eutrophication on phytoplankton dynamics
Senerpont Domis, L.N. de; Waal, D.B. van de; Helmsing, N.R. ; Donk, E. van; Mooij, W.M. - \ 2014
Ecology 95 (2014)6. - ISSN 0012-9658 - p. 1485 - 1495.
climate-change impacts - planktonic herbivore - re-oligotrophication - water temperature - organic-carbon - fresh-waters - peg-model - lake - zooplankton - productivity
The current changes in our climate will likely have far-reaching consequences for aquatic ecosystems. These changes in the climate, however, do not act alone, and are often accompanied by additional stressors such as eutrophication. Both global warming and eutrophication have been shown to affect the timing and magnitude of phytoplankton blooms. Little is known about the combined effects of rising temperatures and eutrophication on the stoichiometry of entire phytoplankton communities. We exposed a natural phytoplankton spring community to different warming and phosphorus-loading scenarios using a full-factorial design. Our results demonstrate that rising temperatures promote the growth rate of an entire phytoplankton community. Furthermore, both rising temperatures and phosphorus loading stimulated the maximum biomass built up by the phytoplankton community. Rising temperatures led to higher carbon¿:¿nutrient stoichiometry of the phytoplankton community under phosphorus-limited conditions. Such a shift towards higher carbon¿:¿nutrient ratios, in combination with a higher biomass buildup, suggests a temperature-driven increase in nutrient use efficiency, the phytoplankton community. Importantly, with higher carbon¿:¿nutrient stoichiometry, phytoplankton is generally of poorer nutritional value for zooplankton. Thus, although warming may result in higher phytoplankton biomass, this may be accompanied by a stoichiometric mismatch between phytoplankton and their grazers, with possible consequences for the entire aquatic food web.
A Unimodal Species Response Model Relating Traits to Environment with Application to Phytoplankton Communities.
Jamil, T. ; Kruk, C. ; Braak, C.J.F. ter - \ 2014
PLoS One 9 (2014)5. - ISSN 1932-6203 - 14 p.
bayesian variable selection - climate-change - ecology - lake - variability - strategies - diversity - habitat - classification - regression
In this paper we attempt to explain observed niche differences among species (i.e. differences in their distribution along environmental gradients) by differences in trait values (e.g. volume) in phytoplankton communities. For this, we propose the trait-modulated Gaussian logistic model in which the niche parameters (optimum, tolerance and maximum) are made linearly dependent on species traits. The model is fitted to data in the Bayesian framework using OpenBUGS (Bayesian inference Using Gibbs Sampling) to identify according to which environmental variables there is niche differentiation among species and traits. We illustrate the method with phytoplankton community data of 203 lakes located within four climate zones and associated measurements on 11 environmental variables and six morphological species traits of 60 species. Temperature and chlorophyll-a (with opposite signs) described well the niche structure of all species. Results showed that about 25% of the variance in the niche centres with respect to chlorophyll-a were accounted for by traits, whereas niche width and maximum could not be predicted by traits. Volume, mucilage, flagella and siliceous exoskeleton are found to be the most important traits to explain the niche centres. Species were clustered in two groups with different niches structures, group 1 high temperature-low chlorophyll-a species and group 2 low temperature-high chlorophyll-a species. Compared to group 2, species in group 1 had larger volume but lower surface area, had more often flagella but neither mucilage nor siliceous exoskeleton. These results might help in understanding the effect of environmental changes on phytoplankton community. The proposed method, therefore, can also apply to other aquatic or terrestrial communities for which individual traits and environmental conditioning factors are available.
Light and Phosphate Competition Between Cylindrospermopsis raciborskii and Microcystis aeruginosa is Strain Dependent
Marinho, V.L.D. ; Souza, M.B. ; Lurling, M. - \ 2013
Microbial Ecology 66 (2013)3. - ISSN 0095-3628 - p. 479 - 488.
harmful algal blooms - cyanobacterium microcystis - genetic diversity - phytoplankton communities - environmental-conditions - growth - phosphorus - lake - temperature - model
The hypothesis that outcomes of phosphorus and light competition between Cylindrospermopsis raciborskii and Microcystis aeruginosa are strain dependent was tested experimentally. Critical requirements of phosphorus (P*) and of light (I*) of two strains of each species were determined through monoculture experiments, which indicated a trade-off between species and also between Microcystis strains. Competition experiments between species were performed using the weakest predicted competitors (with the highest values of P* and of I*) and with the strongest predicted competitors (with the lowest values of P* and of I*). Under light limitation, competition between the weakest competitors led C. raciborskii to dominate. Between the strongest competitors, the opposite was observed, M. aeruginosa displaced C. raciborskii, but both strains co-existed in equilibrium. Under phosphate limitation, competition between the weakest competitors led C. raciborskii to exclude M. aeruginosa, and between the strongest competitors, the opposite was observed, M. aeruginosa displaced C. raciborskii, but the systemdid not reach an equilibrium and both strains were washed out. Hence, outcomes of the competition depended on the pair of competing strains and not only on species or on type of limitation. We concluded that existence of different tradeoffs among strains and between species underlie our results showing that C. raciborskii can either dominate or be displaced byM. aeruginosa when exposed to different conditions of light or phosphate limitation.
Dog poisonings associated with a Microcystis aeruginosa bloom in the Netherlands
Lurling, M. ; Faassen, E.J. - \ 2013
Toxins 5 (2013)3. - ISSN 2072-6651 - p. 556 - 567.
blue-green-algae - cyanobacterial toxins - 1st report - benthic cyanobacteria - anatoxin-a - lake - neurotoxicosis - diversity - identification - heptapeptides
In early autumn 2011, three dogs died after they had been exposed to a Microcystis aeruginosa bloom on Lake Amstelmeer, The Netherlands. The cyanobacterial scum from the lake contained up to 5.27 × 103 ?g g-1 dry-weight microcystin, the vomit of one of the dogs contained on average 94 ?g microcystin g-1 dry-weight. In both cases, icrocystin-LR was the most abundant variant. This is the first report of dog deaths associated with a Microcystis bloom and microcystin poisoning in The Netherlands. © 2013 by the authors; licensee MDPI, Basel, Switzerland.
Growth inhibition and colony formation in the cyanobacterium Microcystis aeruginosa induced by the cyanobacterium Cylindrospermopsis raciborskii
Mello, M.M. ; Soares, M.C.S. ; Roland, F. ; Lürling, M.F.L.L.W. - \ 2012
Journal of Plankton Research 34 (2012)11. - ISSN 0142-7873 - p. 987 - 994.
alga scenedesmus-obliquus - morphological-changes - seasonal succession - phytoplankton - water - lake - blooms - zooplankton - allelopathy - reservoirs
In a tropical reservoir, the cyanobacteria Microcystis aeruginosa and Cylindrospermopsis raciborskii are the dominant species, with changes in dominance throughout the year. Since allelopathy has been suggested as a factor that could promote or stabilize harmful algal blooms, we investigated potential allelopathic effects of C. raciborskii on M. aeruginosa. Microcystis aeruginosa was exposed to exudates of a C. raciborskii monoculture and exudates of mixed cultures of both species. Significant growth inhibition of M. aeruginosa was observed only when it was exposed to exudates from the mixed culture with high proportion of C. raciborskii. This result suggests that the production of growth inhibitors seems to depend on stress (competition) and on the density of the producer species. In contrast to the control, M. aeruginosa formed colonies when exposed to filtrates of mixed cultures. As far as we know, this is the first report on colony induction resulting from the interaction between cyanobacteria. Our results suggest that compounds produced by C. raciborskii may induce defense mechanisms in M. aeruginosa. Our results also indicate specificity in this interaction, since another strain of M. aeruginosa showed different responses.
A physically based model of global freshwater surface temperature
Beek, L.P.H. van; Eikelboom, T. ; Vliet, M.T.H. van; Bierkens, M.F.P. - \ 2012
Water Resources Research 48 (2012). - ISSN 0043-1397
space-time climate - stream temperature - river temperature - lake - variability - dynamics - basins - waves
Temperature determines a range of physical properties of water and exerts a strong control on surface water biogeochemistry. Thus, in freshwater ecosystems the thermal regime directly affects the geographical distribution of aquatic species through their growth and metabolism and indirectly through their tolerance to parasites and diseases. Models used to predict surface water temperature range between physically based deterministic models and statistical approaches. Here we present the initial results of a physically based deterministic model of global freshwater surface temperature. The model adds a surface water energy balance to river discharge modeled by the global hydrological model PCR-GLOBWB. In addition to advection of energy from direct precipitation, runoff, and lateral exchange along the drainage network, energy is exchanged between the water body and the atmosphere by shortwave and longwave radiation and sensible and latent heat fluxes. Also included are ice formation and its effect on heat storage and river hydraulics. We use the coupled surface water and energy balance model to simulate global freshwater surface temperature at daily time steps with a spatial resolution of 0.5 degrees on a regular grid for the period 1976-2000. We opt to parameterize the model with globally available data and apply it without calibration in order to preserve its physical basis with the outlook of evaluating the effects of atmospheric warming on freshwater surface temperature. We validate our simulation results with daily temperature data from rivers and lakes (U.S. Geological Survey (USGS), limited to the USA) and compare mean monthly temperatures with those recorded in the Global Environment Monitoring System (GEMS) data set. Results show that the model is able to capture the mean monthly surface temperature for the majority of the GEMS stations, while the interannual variability as derived from the USGS and NOAA data was captured reasonably well. Results are poorest for the Arctic rivers because the timing of ice breakup is predicted too late in the year due to the lack of including a mechanical breakup mechanism. Moreover, surface water temperatures for tropical rivers were overestimated, most likely due to an overestimation of rainfall temperature and incoming shortwave radiation. The spatiotemporal variation of water temperature reveals large temperature differences between water and atmosphere for the higher latitudes, while considerable lateral transport of heat can be observed for rivers crossing hydroclimatic zones, such as the Nile, the Mississippi, and the large rivers flowing to the Arctic. Overall, our model results show promise for future projection of global surface freshwater temperature under global change.
Quantifying spatial and temporal variability of macroinvertebrate metrics
Keizer-Vlek, H.E. ; Verdonschot, P.F.M. ; Verdonschot, R.C.M. ; Goedhart, P.W. - \ 2012
Ecological Indicators 23 (2012). - ISSN 1470-160X - p. 384 - 393.
multimetric index - statistical power - benthic macroinvertebrates - multivariate-analysis - monitoring programs - sampling variation - community metrics - rare - streams - lake
Since the introductions of the Habitat Directive and the European Water Framework Directive, water authorities are now obliged to monitor changes in conservation value/ecological quality on larger spatial scales (opposed to site scale), as well as to indicate the level of confidence and precision of the results provided by the monitoring programs in their river basin management plans (European Commission, 2000). To meet these requirements, analyses of the statistical power of the monitoring programs should be implemented. Currently, the statistical properties associated with aquatic monitoring programs are often unknown. We collected macroinvertebrate samples from 25 meso-eutrophic drainage ditches in the Netherlands and selected 7 taxonomic richness metrics for the evaluation of spatial and temporal variability. Simulations were performed to investigate the effects of changes in (1) the total number of species included in a taxonomic richness metric and (2) the relative number of rare species included in a taxonomic richness metric. Of the 7 metrics evaluated, the number of common species required the smallest number of monitoring sites, followed by the number of Gastropoda species, and the number of species. Also, results showed that metric variability will decrease when the proportion of rare species included in a taxonomic richness metric is reduced or the total number of species included is increased. Irrespective of the metric applied a large effort will be required to detect change within drainage ditches in the Wieden, due to high spatial variability. Therefore, we need to explore the possibilities of applying alternative more cost-effective methods for sampling and sample processing in biomonitoring programs
The effect of recirculating aquaculture systems on the concentrations of heavy metals in culture water and tissues of Nile tilapia Oreochromis niloticus
Martins, C.I. ; Eding, E.H. ; Verreth, J.A.J. - \ 2011
Food Chemistry 126 (2011)3. - ISSN 0308-8146 - p. 1001 - 1005.
fish - accumulation - wild - substances - anguilla - mykiss - lake
To date, farming fish in recirculating aquaculture systems (RAS) is one of the most environmentally friendly ways of producing fish. However, with the trend towards intensification, and consequently decrease in water exchange rates, these systems may accumulate substances, such as heavy metals, in the water and fish. Inductively-coupled plasma-optical emission spectrometry (ICP-OES) and inductively coupled plasma-mass spectroscope (ICP-MS) were used to determine Al, As, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn, in the water and fish (Nile tilapia Oreochromis niloticus). Three RAS were used, differing in daily water exchange rates (30, 70 and 1500 l/kg feed/d). The concentrations of As, Fe, Mn, Ni and Zn in the water increased with decreasing water exchange rates, suggesting an accumulation of heavy metals as more water was re-used. Such accumulation in the water was, however, not translated into accumulation in the liver and muscle. Accumulation of heavy metals was always higher in the liver than in the muscle; however, As reached 1.61 mg/kg wet weight in the muscle of fish farmed in RAS-70 l/kg feed/d. However, these levels are considerably lower than permissible safety levels for human consumption
Phytoplankton community composition can be predicted best in terms of morphological groups
Kruk, C. ; Peeters, E.T.H.M. ; Nes, E.H. van; Huszar, V.M. ; Costa, L.S. ; Scheffer, M. - \ 2011
Limnology and Oceanography 56 (2011)1. - ISSN 0024-3590 - p. 110 - 118.
functional types - body-size - plankton - ecology - lake - diversity - classification - nutrient - evolution - patterns
We explored how well the aggregated biovolume of groups of species can be predicted from environmental variables using three different classification approaches: morphology-based functional groups, phylogenetic groups, and functional groups proposed by Reynolds. We assessed the relationships between biovolume of each group and environmental conditions using canonical correlation analyses as well as multiple linear regressions, using data from 211 lakes worldwide ranging from subpolar to tropical regions. We compared the results of these analyses with those obtained for single species following the same protocol. While some species appear relatively predictable, a vast majority of the species showed no clear relationship to the environmental conditions we had measured. However, both the multivariate and the regression analyses indicated that morphology-based groups can be predicted better from environmental conditions than groups based on the other classification methods. This suggests that morphology captures ecological function of phytoplankton well, and that functional groups based on morphology may be the most suitable focus for predicting the composition of communities
Optimizing the use of activity traps for aquatic biodiversity studies
Verdonschot, R.C.M. - \ 2010
Journal of the North American Benthological Society 29 (2010)4. - ISSN 0887-3593 - p. 1228 - 1240.
sloten - zoetwaterecologie - bemonsteren - ditches - freshwater ecology - sampling - gammarus-pulex - diel activity - invertebrates - stream - macroinvertebrates - ecology - catches - samples - food - lake
I investigated the effectiveness of activity traps for macroinvertebrate monitoring in shallow, heavily vegetated drainage ditches and explored 2 ways to optimize the use of activity traps for monitoring purposes. I tested the effects of trapping duration (48, 96, and 168 h) and use of attractants (bait and preconditioned leaves). The number of taxa and individuals captured increased with trapping duration. Based on the taxon accumulation curves, deployment times of 48 h and 96 h were equally efficient in capturing new taxa, but a trapping duration of 168 h was much more efficient and resulted in a larger number of taxa collected with every new sample added. Of the attractants offered in the traps, only bait caused differences in the macroinvertebrate assemblage recorded. After 48 h, more predators were captured in traps with bait than in control traps and traps with preconditioned leaves. This effect disappeared with longer trapping duration. Because of their relatively low labor requirements and high level of standardization, activity traps appear to be a valuable tool in lentic biodiversity surveys, especially when deployed for a longer period than has usually been reported. The use of bait is advisable only if capture of specific taxa is required and not for standard monitoring purposes.
Daphnia magna feeding on Cylindrospermopsis raciborskii: the role of food composition, filament length and body size
Panosso, R. ; Lürling, M.F.L.L.W. - \ 2010
Journal of Plankton Research 32 (2010)10. - ISSN 0142-7873 - p. 1393 - 1404.
microcystis-aeruginosa - population-growth - cyanobacterium - zooplankton - temperature - selection - lake - mechanisms - morphology - responses
We investigated the role of filament length of the toxic cyanobacterium Cylindrospermopsis raciborskii on the grazing of Daphnia magna by providing different food mixtures. It was hypothesized that longer C. raciborskii filaments would reduce the clearance rates of D. magna more than shorter ones. Also, C. raciborskii was expected to have a stronger negative impact on the grazing of larger animals. The clearance rates of two D. magna size classes (smaller, 2.0 ± 0.1 mm and larger, 3.1 ± 0.06 mm) were measured in short-term laboratory grazing experiments using individuals fed with two different monocultures of a saxitoxin producer C. raciborskii strain distinguished by filament lengths (average 137 and 61 µm). The cyanobacteria were offered as the sole food source and as a mixture (1:1) with Scenedesmus obliquus. A treatment with only S. obliquus was also applied. The length of C. raciborskii filaments did not have a clear influence on the clearance rates of D. magna within the range we tested. Thus, longer C. raciborskii filaments may not necessarily cause stronger feeding inhibition than shorter ones. Most of the grazing reduction occurred when C. raciborskii was the sole food for either size of D. magna. Larger animals experienced increased feeding inhibition by the addition of C. raciborskii to the diet. The proportion of C. raciborskii relative to suitable food may be a key factor for the outcome of feeding performance of D. magna. We encourage other authors to test the validity of these conclusions over a larger range of filament lengths and on strains with different biochemical makeup.
Using participatory modelling to compensate for data scarcity in environmental planning: A case study from India
Ritzema, H.P. ; Froebrich, J. ; Raju, R. ; Sreenivas, Ch. ; Kselik, R.A.L. - \ 2010
Environmental Modelling & Software 25 (2010)11. - ISSN 1364-8152 - p. 1450 - 1458.
lessons - stakeholder - drainage - lake
Participatory modelling has provided a new approach to overcome the problem of data scarcity which formerly interfered with the environmental planning for the restoration of the Kolleru-Upputeru wetland ecosystem on the east coast of Andhra Pradesh in South India. New ways had to be found to address the shortcomings of traditionally validated simulation models. The traditional validation process was replaced by joint plausibility discussions and shared vision building in order to improve the understanding of cause-effect relationships and proposals for restoration measures. This study has aimed to match the tacit knowledge of the local stakeholders with explicit scientific knowledge in order to create (i) a mutual basis for an integrated approach as opposed to single-issue measures and (ii) a mutual agreement on follow-up steps needed to sustain both the livelihood of the people as well as the wetland ecosystem. The challenge was to address the hydrological and social complexity. On the basis of a literature review, input data for model simulations were generated from the location-specific knowledge of stakeholders and a rapid field appraisal. The model simulations were used to predict the effects of a number of restoration options. In two workshops, these restoration options were discussed with the stakeholders in order to improve the mutual understanding of the complexity of the wetland system and to reach an agreement on the outlines of an integrated action plan. The participatory modelling approach proved to be a useful tool to obtain a consensus of opinions among the stakeholders
Estimating spawning habitat availability in flooded areas of the river Waal, the Netherlands
Wolfshaar, K.E. van de; Ruizeveld de Winter, A.C. ; Straatsma, M.W. ; Brink, N.G.M. ; Leeuw, J.J. de - \ 2010
River Research and Applications 26 (2010)4. - ISSN 1535-1459 - p. 487 - 498.
rutilus-rutilus l - floodplain rivers - fish recruitment - microhabitat use - lucioperca l. - roach - reproduction - growth - model - lake
Fish spawning habitat availability in the river Waal is significantly influenced by seasonal and annual variations in discharge. In this paper we develop habitat suitability models, based on a literature survey of spawning preferences of the commonly occurring species roach (Rutilus rutilus), bream (Abramis brama), pikeperch (Sander lucioperca) and bleak (Alburnus alburnus). Within the resulting models water depth, flow velocity, water temperature and vegetation type were the most significant environmental parameters. Spatial data for the parameters were derived from a 2-D hydrodynamic model and detailed monitoring database. The area of suitable habitat available for spawning was calculated using the HABITAT software, based on species-specific suitability models and the environmental characteristics of two study sites on the river Waal over a 3 year period (1997-1999). The predicted available spawning area was compared with field data on the recruitment of young fish of each species for the same years and locations. There was a positive relationship between predicted available habitat and observed young of the year (YOY) densities for bream, roach and pikeperch. A negative relationship was recorded between predicted available area and observed YOY densities for bleak. The results indicate that optimal hydrological and hydraulic conditions differ even for species that are widely considered eurytopic. Moreover, annual differences in habitat availability indicate a strong influence of hydrological variability on population dynamics.
A morphological classification capturing functional variation in phytoplankton
Kruk, C. ; Huszar, V.M. ; Peeters, E.T.H.M. ; Bonilla, S. ; Costa, L. ; Lürling, M.F.L.L.W. ; Reynolds, C.S. ; Scheffer, M. - \ 2010
Freshwater Biology 55 (2010)3. - ISSN 0046-5070 - p. 614 - 627.
fresh-water phytoplankton - community ecology - summer phytoplankton - body-size - long-term - lake - variability - shallow - trait - fish
1. A logical way of distinguishing functional groups of phytoplankton is to cluster species according to their functional traits, such as growth rate and nutrient assimilation constants. However, data for such an approach are lacking for the vast majority of the species. 2. In this study, we show that a classification based on simple morphological traits may capture much of the variability in functional properties among the phytoplankton. We used information on more than 700 freshwater species, from more than 200 lakes situated in climate zones ranging from subpolar to tropical. 3. Morphological characteristics correlated well with functional properties, such as growth rate and sinking rate, and also with the population size and biomass attained in the field. This suggests that morphology is a good predictor of the functional characteristics of species. 4. Cluster analysis was used to define seven species groups based on morphology. Although some of the clusters are taxonomically homogeneous, others include species of several separate divisions. Functional traits (not used for the classification) differed significantly among the clusters, suggesting that the clusters may indeed represent meaningful functional groups. 5. Advantages of our morphological approach to classification include its objectivity, its independence from taxonomic affiliations, and the relative ease of its application to the majority of species for which physiological traits are unknown and are not readily determined
Origin of Spanish invasion by the zebra mussel, Dreissena polymorpha (Pallas, 1771) revealed by amplified fragment length polymorphism (AFLP) fingerprinting
Rajagopal, S. ; Pollux, B.J.A. ; Peters, J.L. ; Cremers, G. ; Moon- van der Staay, S.Y. ; Alen, T. van; Eygensteyn, J. ; Hoek, A.H.A.M. van; Palau, A. ; Vaate, A.B. de; Velde, G. van der - \ 2009
Biological Invasions 11 (2009)9. - ISSN 1387-3547 - p. 2147 - 2159.
water-quality management - large-river system - united-states - genetic-variability - phylogenetic trees - native bivalves - dispersal - lake - inference - dynamics
The zebra mussel, Dreissena polymorpha is an aquatic nuisance invasive species originally native to the Ponto-Caspian region where it is found in lakes and delta areas of large rivers draining into the Black and Caspian seas. The dispersal of D. polymorpha began at the end of the 18th century, at a time when shipping trade become increasingly important and many canals were built for linking different navigable river systems in Europe. Over the past 200 years, zebra mussels spread to most of the lakes, rivers and waterways in Europe by a combination of natural and anthropogenic dispersal mechanisms. D. polymorpha invaded Spain around 2001, being found for the first time in the Riba-roja reservoir at the lower part of the Ebro River, North-East Spain. The relatively late invasion of Spain was most likely caused by the presence of the Pyrenees, which isolated the Iberian Peninsula from the rest of the European continent, and acted as a barrier to the dispersal of D. polymorpha. In recent studies, molecular genetic methods have successfully been used to determine phylo-geographic relationships, which may reflect invasion corridors and can help retrace source populations. Zebra mussels from populations in Great Britain, The Netherlands, Belgium, France, Germany, Spain, Italy, Romania and North America were analyzed using PCR based amplified fragment length polymorphism (AFLP)-fingerprinting to determine the source population of D. polymorpha in Spain. The phylogenetic analyses and pair-wise genetic distances revealed that the recent invasion of zebra mussels in Spain is most likely from France.
Seasonal Altitudinal movements of golden takin in the Qinling Mountains of China
Zeng, Z.G. ; Skidmore, A.K. ; Song, Y.L. ; Wang, T.J. ; Gong, H.S. - \ 2008
Journal of Wildlife Management 72 (2008)3. - ISSN 0022-541X - p. 611 - 617.
woodland caribou - tailed deer - migration - parks - lake
We studied seasonal movements of golden takin (Budorcas taxicolor bedfordi), a large, social, forest-dwelling ungulate, by radiotracking and field surveys during 1995¿1996 and 2002¿2005 at Foping National Nature Reserve on the southern slope of the Qinling Mountains, China. Takins inhabited forests and subalpine meadows at an altitudinal range from 1,360 m to 2,890 m. Our results showed that golden takins had a complicated seasonal movement pattern and underwent altitudinal migration 4 times each year. Takins occupied a high-altitude range during summer, stayed at low-altitude ranges for short periods during spring and autumn, and resided at an intermediate-altitude range during winter. Changes in plant phenology may have caused seasonal movements. Reserves for takin conservation should incorporate lower altitude habitats than those takins use in spring and autumn, and seasonal movements by takins should be protected from disturbance by human activities.
Relationships among water quality, food resources, fish diet and fish growth in polyculture ponds: A multivariate approach
Rahman, M.M. ; Nagelkerke, L.A.J. ; Verdegem, M.C.J. ; Wahab, M.A. ; Verreth, J.A.J. - \ 2008
Aquaculture 275 (2008)1-4. - ISSN 0044-8486 - p. 108 - 115.
carp cyprinus-carpio - phytoplankton growth - aquaculture ponds - zooplankton - oxygen - population - phosphorus - sediment - size - lake
We examined the influence of addition of common carp (Cyprinus carpio) and artificial feed in rohu (Labeo rohita) ponds. We analyzed the relationships among four datasets on different components of the pond food web (water quality, food availability, natural food intake, and fish growth and production) with the aim to examine the effects of the addition of common carp and/or artificial feed on the different components of the pond food web, and to analyze the nature and strength of the interactions between these components. We used redundancy analysis (RDA) to investigate these effects and interactions. We found that the addition of common carp increased bio-available N and P in the water column. Artificial feed addition increased N and P only in the presence of common carp. N and P increases were more pronounced in the presence of 0.5 than in the presence of 1 common carp m¿ 2. Plankton availability was strongly positively correlated with bio-available N and P. Phytoplankton availability correlated strongest with PO4¿P, and zooplankton availability correlated strongest with PO4¿P and DO. Natural food intake in rohu was positively correlated with plankton availability in the pond water and rohu growth was also positively correlated with natural food intake. Rohu preferred plankton over artificial feed, which acted as a fertilizer for rohu growth. Common carp preferred artificial feed over natural food and its growth was higher in the presence of artificial feed and negatively correlated with natural food availability
An individual-based approach to model spatial population dynamics of invertebrates in aquatic ecosystems after pesticide contamination
Brink, P.J. van den; Verboom, J. ; Baveco, J.M. ; Heimbach, F. - \ 2007
Environmental Toxicology and Chemistry 26 (2007)10. - ISSN 0730-7268 - p. 2226 - 2236.
isopod asellus-aquaticus - life-history - crustacea - growth - stream - water - lake
In the present study we present a population model (Metapopulation model for Assessing Spatial and Temporal Effects of Pesticides [MASTEP]) describing the effects on and recovery of the waterlouse Asellus aquaticus after exposure to a fast-acting, nonpersistent insecticide as a result of spray drift in pond, ditch, and stream scenarios. The model used the spatial and temporal distribution of the exposure in different treatment conditions as an input parameter. A dose¿response relation derived from a hypothetical mesocosm study was used to link the exposure with the effects. The modeled landscape was represented as a lattice of 1- by 1-m cells. The model included processes of mortality of A. aquaticus, life history, random walk between cells, density dependence of population regulation, and, in the case of the stream scenario, medium-distance drift of A. aquaticus due to flow. All parameter estimates were based on expert judgment and the results of a thorough review of published information on the ecology of A. aquaticus. In the treated part of the water body, the ditch scenario proved to be the worst-case situation, due to the absence of drift of A. aquaticus. Effects in the pond scenario were smaller because the pond was exposed from one side, allowing migration from the other, less contaminated side. The results of the stream scenario showed the importance of including drift for the population recovery in the 100-m stretch of the stream that was treated. It should be noted, however, that the inclusion of drift had a negligible impact on numbers in the stream as a whole (600 m).
Impact of polychlorinated biphenyl and polycyclic aromatic hydrocarbon sequestration in sediment on bioaccumulation in aquatic food webs
Moermond, C.T.A. ; Roessink, I. ; Jonker, M.T.O. ; Meijer, T. ; Koelmans, A.A. - \ 2007
Environmental Toxicology and Chemistry 26 (2007)4. - ISSN 0730-7268 - p. 607 - 615.
hydrophobic organic-chemicals - black carbon - benthic organisms - contact time - bioavailability - desorption - sorption - lake - accumulation - extraction
It is not clear whether sequestration or aging of organic chemicals like polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) limits accumulation in higher levels of aquatic food chains. Therefore, the effect of aging on accumulation was studied in 1-m3 model ecosystems that mimicked fish-dominated, macrophyte-dominated, and fish- and macrophyte-dominated shallow lakes. Also treatments without fish and macrophytes were included. General characteristics, biomasses, total (Soxhlet-extractable), and labile (6-h Tenax-extractable) PCB and PAH concentrations in sediment and biota were monitored over time. Accumulation data for PCB 28, PCB 149, and fluoranthene (native to the sediment taken from the field) were compared to those for spiked analogues PCB 29, PCB 155, and fluoranthene-d10. Labile fractions for spiked compounds were higher than for their native analogues and decreased over time, suggesting sequestration in the sediment. In the majority of cases, 6-h Tenax-extractable concentrations correlated better with concentrations in biota than Soxhlet-extractable concentrations. Ecosystem structure affected food web accumulation, but replicate variability was too high to detect clear treatment effects. Differences in accumulation between spiked compounds and their native analogues indicated an effect of aging for invertebrates, macrophytes, and benthivorous fish. Thus, aging may translate directly into reduced uptake at higher trophic levels.
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