Publications by authors named "Elisabeth J Faassen"

24 Publications

  • Page 1 of 1

Chitosan as a Coagulant to Remove Cyanobacteria Can Cause Microcystin Release.

Toxins (Basel) 2020 11 10;12(11). Epub 2020 Nov 10.

Aquatic Ecology and Water Quality Management Group, Department of Environmental Sciences, Wageningen University, Droevendaalsesteeg 3a, 6708 PB Wageningen, The Netherlands.

Chitosan has been tested as a coagulant to remove cyanobacterial nuisance. While its coagulation efficiency is well studied, little is known about its effect on the viability of the cyanobacterial cells. This study aimed to test eight strains of the most frequent bloom-forming cyanobacterium, , exposed to a realistic concentration range of chitosan used in lake restoration management (0 to 8 mg chitosan L). We found that after 1 h of contact with chitosan, in seven of the eight strains tested, photosystem II efficiency was decreased, and after 24 h, all the strains tested were affected. EC values varied from 0.47 to > 8 mg chitosan L between the strains, which might be related to the amount of extracellular polymeric substances. Nucleic acid staining (Sytox-Green) illustrated the loss of membrane integrity in all the strains tested, and subsequent leakage of pigments was observed, as well as the release of intracellular microcystin. Our results indicate that strain variability hampers generalization about species response to chitosan exposure. Hence, when used as a coagulant to manage cyanobacterial nuisance, chitosan should be first tested on the natural site-specific biota on cyanobacteria removal efficiency, as well as on cell integrity aspects.
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http://dx.doi.org/10.3390/toxins12110711DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7696597PMC
November 2020

Copepod Prey Selection and Grazing Efficiency Mediated by Chemical and Morphological Defensive Traits of Cyanobacteria.

Toxins (Basel) 2020 07 21;12(7). Epub 2020 Jul 21.

Center for Coastal Limnological and Marine Studies (CECLIMAR), Campus Litoral Norte, Universidade Federal de Rio Grande de Sul, 95625-000 Imbé, Brazil.

Phytoplankton anti-grazer traits control zooplankton grazing and are associated with harmful blooms. Yet, how morphological versus chemical phytoplankton defenses regulate zooplankton grazing is poorly understood. We compared zooplankton grazing and prey selection by contrasting morphological (filament length: short vs. long) and chemical (saxitoxin: STX- vs. STX+) traits of a bloom-forming cyanobacterium () offered at different concentrations in mixed diets with an edible phytoplankton to a copepod grazer. The copepod selectively grazed on the edible prey (avoidance of cyanobacteria) even when the cyanobacterium was dominant. Avoidance of the cyanobacterium was weakest for the "short STX-" filaments and strongest for the other three strains. Hence, filament size had an effect on cyanobacterial avoidance only in the STX- treatments, while toxin production significantly increased cyanobacterial avoidance regardless of filament size. Moreover, cyanobacterial dominance reduced grazing on the edible prey by almost 50%. Results emphasize that the dominance of filamentous cyanobacteria such as can interfere with copepod grazing in a trait specific manner. For cyanobacteria, toxin production may be more effective than filament size as an anti-grazer defense against selectively grazing zooplankton such as copepods. Our results highlight how multiple phytoplankton defensive traits interact to regulate the producer-consumer link in plankton ecosystems.
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http://dx.doi.org/10.3390/toxins12070465DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7404970PMC
July 2020

Effects of guanotrophication and warming on the abundance of green algae, cyanobacteria and microcystins in Lake Lesser Prespa, Greece.

PLoS One 2020 11;15(3):e0229148. Epub 2020 Mar 11.

Aquatic Ecology and Water Quality Management Group, Department of Environmental Sciences, Wageningen University, Wageningen, The Netherlands.

Lake Lesser Prespa in Greece is a vital breeding habitat for the Dalmatian and Great White Pelican and a shelter for numerous rare and endemic species. However, eutrophication processes are distressing the lake system and the outbreaks of cyanobacterial blooms during the warm months may pose a threat to aquatic organisms due to the presence of microcystins (MCs). In this study we hypothesize that nutrients (eutrophication), nutrient-rich pelican droppings (guanotrophication) and warming (climate change) can affect the algal growth and MCs production in the water layer of Lake Lesser Prespa. Seston collected from three lake sites was incubated at ambient (20°C) and high (30°C) temperature with or without the addition of nutrients (nitrogen (N), phosphorus (P)), or pelican droppings. Results showed increased chlorophyll-a at higher temperature (30°C). N addition yielded higher chlorophyll-a levels than the non-treated water or when only P was added. The addition of both N and P as well as the addition of pelican dropping resulted in the highest chlorophyll-a at both temperatures. Notably, in the dropping-treatments, cyanobacteria and MCs were promoted while changes were evoked in the relative contribution of toxic MC-variants. Guanotrophication may thus influence the cyanobacterial dynamics and most likely their toxicity profile at Lesser Prespa.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0229148PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7065754PMC
June 2020

How the Neurotoxin β--Methylamino-l-Alanine Accumulates in Bivalves: Distribution of the Different Accumulation Fractions among Organs.

Toxins (Basel) 2020 01 21;12(2). Epub 2020 Jan 21.

UMR-I 02 INERIS-URCA-ULH SEBIO, Unité Stress Environnementaux et BIOsurveillance des milieux aquatiques, UFR Sciences Exactes et Naturelles, Moulin de la Housse, BP 1039, 51687 Reims CEDEX 2, France.

The environmental neurotoxin β-methylamino-l-alanine (BMAA) may represent a risk for human health. BMAA accumulates in freshwater and marine organisms consumed by humans. However, few data are available about the kinetics of BMAA accumulation and detoxification in exposed organisms, as well as the organ distribution and the fractions in which BMAA is present in tissues (free, soluble bound or precipitated bound cellular fractions). Here, we exposed the bivalve mussel to 7.5 µg of dissolved BMAA/mussel/3 days for 21 days, followed by 21 days of depuration in clear water. At 1, 3, 8, 14 and 21 days of exposure and depuration, the hemolymph and organs (digestive gland, the gills, the mantle, the gonad and muscles/foot) were sampled. Total BMAA as well as free BMAA, soluble bound and precipitated bound BMAA were quantified by tandem mass spectrometry. Free and soluble bound BMAA spread throughout all tissues from the first day of exposure to the last day of depuration, without a specific target organ. However, precipitated bound BMAA was detected only in muscles and foot from the last day of exposure to day 8 of depuration, at a lower concentration compared to free and soluble bound BMAA. In soft tissues (digestive gland, gonad, gills, mantle and muscles/foot), BMAA mostly accumulated as a free molecule and in the soluble bound fraction, with variations occurring between the two fractions among tissues and over time. The results suggest that the assessment of bivalve contamination by BMAA may require the quantification of total BMAA in whole individuals when possible.
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http://dx.doi.org/10.3390/toxins12020061DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7076761PMC
January 2020

A European Multi Lake Survey dataset of environmental variables, phytoplankton pigments and cyanotoxins.

Sci Data 2018 10 23;5:180226. Epub 2018 Oct 23.

Lammi Biological Station, University of Helsinki, 16900 Lammi, Finland.

Under ongoing climate change and increasing anthropogenic activity, which continuously challenge ecosystem resilience, an in-depth understanding of ecological processes is urgently needed. Lakes, as providers of numerous ecosystem services, face multiple stressors that threaten their functioning. Harmful cyanobacterial blooms are a persistent problem resulting from nutrient pollution and climate-change induced stressors, like poor transparency, increased water temperature and enhanced stratification. Consistency in data collection and analysis methods is necessary to achieve fully comparable datasets and for statistical validity, avoiding issues linked to disparate data sources. The European Multi Lake Survey (EMLS) in summer 2015 was an initiative among scientists from 27 countries to collect and analyse lake physical, chemical and biological variables in a fully standardized manner. This database includes in-situ lake variables along with nutrient, pigment and cyanotoxin data of 369 lakes in Europe, which were centrally analysed in dedicated laboratories. Publishing the EMLS methods and dataset might inspire similar initiatives to study across large geographic areas that will contribute to better understanding lake responses in a changing environment.
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http://dx.doi.org/10.1038/sdata.2018.226DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6198753PMC
October 2018

The Impact of Warming and Nutrients on Algae Production and Microcystins in Seston from the Iconic Lake Lesser Prespa, Greece.

Toxins (Basel) 2018 04 2;10(4). Epub 2018 Apr 2.

Aquatic Ecology & Water Quality Management Group, Department of Environmental Sciences, Wageningen University, PO Box 47, 6700 AA Wageningen, The Netherlands.

Lake Lesser Prespa and its adjacent pond, Vromolimni in Greece, is a shallow freshwater system and a highly protected area hosting an exceptional biodiversity. The occurrence of microcystins (MCs) producing cyanobacterial blooms in these waters during recent years can be harmful to the wildlife. We tested the hypothesis that both cyanobacterial biomass and MCs are strongly influenced by nutrients (eutrophication) and warming (climate change). Lake and pond water was collected from two sites in each water body in 2013 and incubated at three temperatures (20 °C, 25 °C, 30 °C) with or without additional nutrients (nitrogen +N, phosphorus +P and both +N and +P). Based on both biovolume and chlorophyll-a concentrations, cyanobacteria in water from Lesser Prespa were promoted primarily by combined N and P additions and to a lesser extent by N alone. Warming seemed to yield more cyanobacteria biomass in these treatments. In water from Vromolimni, both N alone and N+P additions increased cyanobacteria and a warming effect was hardly discernible. MC concentrations were strongly increased by N and N+P additions in water from all four sites, which also promoted the more toxic variant MC-LR. Hence, both water bodies seem particularly vulnerable to further N-loading enhancing MC related risks.
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http://dx.doi.org/10.3390/toxins10040144DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5923310PMC
April 2018

Effect of the toxin (microcystin) content of Microcystis on copepod grazing.

Harmful Algae 2016 02 7;52:34-45. Epub 2016 Jan 7.

Department of Environmental Sciences, Aquatic Ecology and Water Quality Management Group, Wageningen University, Wageningen, The Netherlands; Department of Aquatic Ecology, Netherlands Institute of Ecology - Royal Netherlands Academy of Arts and Science, Wageningen, The Netherlands.

Although phytoplankton chemical defense may regulate plankton dynamics, demonstrating an ecologically relevant anti-grazer cue is challenging. Presented here is a novel approach to evaluate the quantitative effect of microcystin (MC), the most studied group of cyanobacterial metabolites, on grazing by the common copepod Eudiaptomus gracilis. A temperature-induced gradient in the intracellular MC concentration of three different Microcystis strains enabled the comparison of grazing pressure on cells of the same cyanobacterial strain producing different amounts of MC, in a diet with alternative food (Chlamydomonas). In all treatments, grazing pressure on Microcystis was inversely related to its MC-LR content, while selection for alternative prey was positively related to the MC-LR content of Microcystis. Moreover, grazing on Chlamydomonas also declined with increasing Microcystis MC-LR content, suggesting toxicity related inhibition of E. gracilis. The negative relation between cellular MC-LR concentration and feeding responses supported the anti-grazer hypothesis. Not all MC variants responded to temperature, and some were therefore not associated to grazing responses. Using an induced gradient in the concentration of a suspected phytoplankton defense metabolite to evaluate its quantitative relationship with grazing pressure offers an improved inference on the ecological roles of toxins. Results suggest that either MC-LR or a correlating trait may be inversely linked to the grazer pressure on Microcystis.
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http://dx.doi.org/10.1016/j.hal.2015.12.008DOI Listing
February 2016

A Collaborative Evaluation of LC-MS/MS Based Methods for BMAA Analysis: Soluble Bound BMAA Found to Be an Important Fraction.

Mar Drugs 2016 Feb 29;14(3). Epub 2016 Feb 29.

Department of Environmental Science and Analytical Chemistry, Stockholm University, SE-10691 Stockholm, Sweden.

Exposure to β-N-methylamino-l-alanine (BMAA) might be linked to the incidence of amyotrophic lateral sclerosis, Alzheimer's disease and Parkinson's disease. Analytical chemistry plays a crucial role in determining human BMAA exposure and the associated health risk, but the performance of various analytical methods currently employed is rarely compared. A CYANOCOST initiated workshop was organized aimed at training scientists in BMAA analysis, creating mutual understanding and paving the way towards interlaboratory comparison exercises. During this workshop, we tested different methods (extraction followed by derivatization and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) analysis, or directly followed by LC-MS/MS analysis) for trueness and intermediate precision. We adapted three workup methods for the underivatized analysis of animal, brain and cyanobacterial samples. Based on recovery of the internal standard D₃BMAA, the underivatized methods were accurate (mean recovery 80%) and precise (mean relative standard deviation 10%), except for the cyanobacterium Leptolyngbya. However, total BMAA concentrations in the positive controls (cycad seeds) showed higher variation (relative standard deviation 21%-32%), implying that D₃BMAA was not a good indicator for the release of BMAA from bound forms. Significant losses occurred during workup for the derivatized method, resulting in low recovery (<10%). Most BMAA was found in a trichloroacetic acid soluble, bound form and we recommend including this fraction during analysis.
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http://dx.doi.org/10.3390/md14030045DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4820299PMC
February 2016

Toxicity Overrides Morphology on Cylindrospermopsis raciborskii Grazing Resistance to the Calanoid Copepod Eudiaptomus gracilis.

Microb Ecol 2016 May 18;71(4):835-44. Epub 2016 Feb 18.

Department of Environmental Sciences, Aquatic Ecology and Water Quality Management Group, Wageningen University, Wageningen, The Netherlands.

Toxicity and morphology may function as defense mechanisms of bloom-forming cyanobacteria against zooplankton grazing. Yet, the relative importance of each of these factors and their plasticity remains poorly known. We tested the effects of chemical and morphological traits of the bloom-forming cyanobacterium Cylindrospermopsis raciborskii on the feeding response of the selective feeder Eudiaptomus gracilis (Calanoida, Copepoda), using a saxitoxin-producing strain (STX+) and a non-saxitoxin (STX-)-producing strain as food. From these two chemotypes, we established cultures of three different morphotypes that differed in filament length (short, medium, and long) by incubating the strains at 17, 25, and 32 °C. We hypothesized that the inhibitory effects of saxitoxins determine the avoidance of C. raciborskii, and that morphology would only become relevant in the absence of saxitoxins. Temperature affected two traits: higher temperature resulted in significantly shorter filaments in both strains and led to much higher toxin contents in the STX+ strain (1.7 μg eq STX L(-1) at 17 °C, 7.9 μg eq STX L(-1) at 25 °C, and 25.1 μg eq STX L(-1) at 32 °C). Copepods strongly reduced the ingestion of the STX+ strain in comparison with STX- cultures, regardless of filament length. Conversely, consumption of shorter filaments was significantly higher in the STX- strain. The great plasticity of morphological and chemical traits of C. raciborskii and their resultant contrasting effects on the feeding behavior of zooplankton might explain the success of this cyanobacterium in a variety of aquatic environments.
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http://dx.doi.org/10.1007/s00248-016-0734-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4823325PMC
May 2016

Elevated pCO2 causes a shift towards more toxic microcystin variants in nitrogen-limited Microcystis aeruginosa.

FEMS Microbiol Ecol 2016 Feb 15;92(2). Epub 2015 Dec 15.

Department of Aquatic Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Droevendaalsesteeg 10, Wageningen 6708 PB, The Netherlands.

Elevated pCO2 may promote phytoplankton growth, and potentially alleviate carbon limitation during dense blooms. Under nitrogen-limited conditions, elevated pCO2 may furthermore alter the phytoplankton carbon-nitrogen (C:N) balance and thereby the synthesis of secondary metabolites, such as cyanobacterial toxins. A common group of these toxins are the microcystins, with variants that differ not only in C:N stoichiometry, but also in toxicity. Here, we hypothesized that elevated pCO2 will increase the cellular C:N ratios of cyanobacteria, thereby promoting the more toxic microcystin variants with higher C:N ratios. To test this hypothesis, we performed chemostat experiments under nitrogen-limited conditions, exposing three Microcystis aeruginosa strains to two pCO2 treatments: 400 and 1200 μatm. Biomass, cellular C:N ratios and total microcystin contents at steady state remained largely unaltered in all three strains. Across strains and treatments, however, cellular microcystin content decreased with increasing cellular C:N ratios, suggesting a general stoichiometric regulation. Furthermore, as predicted, microcystin variants with higher C:N ratios generally increased with elevated pCO2, while the variant with a low C:N ratio decreased. Thus, elevated pCO2 under nitrogen-limited conditions may shift the cellular microcystin composition towards the more toxic variants. Such CO2-driven changes may have consequences for the toxicity of Microcystis blooms.
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http://dx.doi.org/10.1093/femsec/fiv159DOI Listing
February 2016

Trans generational effects of the neurotoxin BMAA on the aquatic grazer Daphnia magna.

Aquat Toxicol 2015 Nov 9;168:98-107. Epub 2015 Oct 9.

Wageningen University, P.O. Box 47, Wageningen, 6700 DD, The Netherlands; NIOO-KNAW, Droevendaalsesteeg 10, Wageningen, 6708 PB, The Netherlands. Electronic address:

β-N-Methylamino-l-alanine (BMAA) is a neurotoxin that is suspected to play a role in the neurological diseases amyotrophic lateral sclerosis, Alzheimer's disease and Parkinson's disease. BMAA has been detected in phytoplankton and globally, the main exposure routes for humans to BMAA are through direct contact with phytoplankton-infested waters and consumption of BMAA-contaminated fish and invertebrates. As BMAA can be transferred from mothers to offspring in mammals, BMAA exposure is expected to have transgenerational effects. The aim of our study was to determine whether maternal exposure to BMAA affects offspring fitness in zooplankton. We performed a multigenerational life history experiment and a multigenerational uptake experiment with the water flea Daphnia magna as a model species. In both experiments, offspring from nonexposed and exposed mothers were raised in clean and BMAA-containing medium. Direct exposure to 110μg/l BMAA reduced survival, somatic growth, reproduction and population growth. Maternal exposure did not affect D. magna fitness: animals from exposed mothers that were raised in clean medium had a higher mortality and produced lighter neonates than the controls, but this did not result in lower population growth rates. No evidence of adaptation was found. Instead, multigeneration exposure to BMAA had a negative effect: animals that were exposed during two generations had a lower brood viability and neonate weight than animals born from unexposed mothers, but raised in BMAA-containing medium. Maternal transfer of BMAA was observed, but BMAA concentrations in neonates raised in BMAA containing medium were similar for animals born from exposed and unexposed mothers. Our results indicate that zooplankton might be an important vector for the transfer of BMAA along the pelagic food chain, but whether BMAA plays a role in preventing zooplankton from controlling cyanobacterial blooms needs further investigation.
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http://dx.doi.org/10.1016/j.aquatox.2015.09.018DOI Listing
November 2015

Effects of hydrogen peroxide and ultrasound on biomass reduction and toxin release in the cyanobacterium, Microcystis aeruginosa.

Toxins (Basel) 2014 Dec 10;6(12):3260-80. Epub 2014 Dec 10.

Aquatic Ecology and Water Quality Management Group, Department of Environmental Sciences, Wageningen University, P.O. Box 47, 6700 AA Wageningen, The Netherlands.

Cyanobacterial blooms are expected to increase, and the toxins they produce threaten human health and impair ecosystem services. The reduction of the nutrient load of surface waters is the preferred way to prevent these blooms; however, this is not always feasible. Quick curative measures are therefore preferred in some cases. Two of these proposed measures, peroxide and ultrasound, were tested for their efficiency in reducing cyanobacterial biomass and potential release of cyanotoxins. Hereto, laboratory assays with a microcystin (MC)-producing cyanobacterium (Microcystis aeruginosa) were conducted. Peroxide effectively reduced M. aeruginosa biomass when dosed at 4 or 8 mg L-1, but not at 1 and 2 mg L-1. Peroxide dosed at 4 or 8 mg L-1 lowered total MC concentrations by 23%, yet led to a significant release of MCs into the water. Dissolved MC concentrations were nine-times (4 mg L-1) and 12-times (8 mg L-1 H2O2) higher than in the control. Cell lysis moreover increased the proportion of the dissolved hydrophobic variants, MC-LW and MC-LF (where L = Leucine, W = tryptophan, F = phenylalanine). Ultrasound treatment with commercial transducers sold for clearing ponds and lakes only caused minimal growth inhibition and some release of MCs into the water. Commercial ultrasound transducers are therefore ineffective at controlling cyanobacteria.
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http://dx.doi.org/10.3390/toxins6123260DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4280534PMC
December 2014

Eutrophic urban ponds suffer from cyanobacterial blooms: Dutch examples.

Environ Sci Pollut Res Int 2014 6;21(16):9983-94. Epub 2014 May 6.

Aquatic Ecology & Water Quality Management Group, Department of Environmental Sciences, Wageningen University, P.O. Box 47, 6700 AA, Wageningen, The Netherlands,

Ponds play an important role in urban areas. However, cyanobacterial blooms counteract the societal need for a good water quality and pose serious health risks for citizens and pets. To provide insight into the extent and possible causes of cyanobacterial problems in urban ponds, we conducted a survey on cyanobacterial blooms and studied three ponds in detail. Among 3,500 urban ponds in the urbanized Dutch province of North Brabant, 125 showed cyanobacterial blooms in the period 2009-2012. This covered 79% of all locations registered for cyanobacterial blooms, despite the fact that urban ponds comprise only 11% of the area of surface water in North Brabant. Dominant bloom-forming genera in urban ponds were Microcystis, Anabaena and Planktothrix. In the three ponds selected for further study, the microcystin concentration of the water peaked at 77 μg l(-1) and in scums at 64,000 μg l(-1), which is considered highly toxic. Microcystin-RR and microcystin-LR were the most prevalent variants in these waters and in scums. Cyanobacterial chlorophyll-a peaked in August with concentrations up to 962 μg l(-1) outside of scums. The ponds were highly eutrophic with mean total phosphorus concentrations between 0.16 and 0.44 mg l(-1), and the sediments were rich in potential releasable phosphorus. High fish stocks dominated by carp lead to bioturbation, which also favours blooms. As urban ponds in North Brabant, and likely in other regions, regularly suffer from cyanobacterial blooms and citizens may easily have contact with the water and may ingest cyanobacterial material during recreational activities, particularly swimming, control of health risk is of importance. Monitoring of cyanobacteria and cyanobacterial toxins in urban ponds is a first step to control health risks. Mitigation strategies should focus on external sources of eutrophication and consider the effect of sediment P release and bioturbation by fish.
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http://dx.doi.org/10.1007/s11356-014-2948-yDOI Listing
May 2015

Presence of the neurotoxin BMAA in aquatic ecosystems: what do we really know?

Toxins (Basel) 2014 Mar 21;6(3):1109-38. Epub 2014 Mar 21.

Aquatic Ecology & Water Quality Management Group, Wageningen University, P.O. Box 47, Wageningen 6700 DD, The Netherlands.

The neurotoxin β-N-methylamino-L-alanine (BMAA) is suspected to play a role in the neurological diseases amyotrophic lateral sclerosis, Alzheimer's disease, and Parkinson's disease. BMAA production by cyanobacteria has been reported and contact with cyanobacteria infested waters or consumption of aquatic organisms are possible pathways to human exposure. However, there is little consensus regarding whether BMAA is present in cyanobacteria or not, and if so, at what concentrations. The aim of this review is to indicate the current state of knowledge on the presence of BMAA in aquatic ecosystems. Some studies have convincingly shown that BMAA can be present in aquatic samples at the µg/g dry weight level, which is around the detection limit of some equally credible studies in which no BMAA was detected. However, for the majority of the reviewed articles, it was unclear whether BMAA was correctly identified, either because inadequate analytical methods were used, or because poor reporting of analyses made it impossible to verify the results. Poor analysis, reporting and prolific errors have shaken the foundations of BMAA research. First steps towards estimation of human BMAA exposure are to develop and use selective, inter-laboratory validated methods and to correctly report the analytical work.
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http://dx.doi.org/10.3390/toxins6031109DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3968380PMC
March 2014

Occurrence of the microcystins MC-LW and MC-LF in Dutch surface waters and their contribution to total microcystin toxicity.

Mar Drugs 2013 Jul 22;11(7):2643-54. Epub 2013 Jul 22.

Aquatic Ecology & Water Quality Management Group, Wageningen University, PO Box 47, Wageningen 6700 AA, The Netherlands.

Microcystins (MCs) are the most frequently found cyanobacterial toxins in freshwater systems. Many MC variants have been identified and variants differ in their toxicity. Recent studies showed that the variants MC-LW and MC-LF might be more toxic than MC-LR, the variant that is most abundant and mostly used for risk assessments. As little is known about the presence of these two variants in The Netherlands, we determined their occurrence by analyzing 88 water samples and 10 scum samples for eight MC variants ((dm-7-)MC-RR, MC-YR, (dm-7-)MC-LR, MC-LY, MC-LW and MC-LF) by liquid chromatography with tandem mass spectrometry detection. All analyzed MC variants were detected, and MC-LW and/or MC-LF were present in 32% of the MC containing water samples. When MC-LW and MC-LF were present, they contributed to nearly 10% of the total MC concentrations, but due to their suspected high toxicity, their average contribution to the total MC toxicity was estimated to be at least 45%. Given the frequent occurrence and possible high toxicity of MC-LW and MC-LF, it seems better to base health risk assessments on the toxicity contributions of different MC variants than on MC-LR concentrations alone.
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http://dx.doi.org/10.3390/md11072643DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3736443PMC
July 2013

Evaluation of a commercial enzyme linked immunosorbent assay (ELISA) for the determination of the neurotoxin BMAA in surface waters.

PLoS One 2013 7;8(6):e65260. Epub 2013 Jun 7.

Department of Environmental Sciences, Wageningen University, Wageningen, The Netherlands.

The neurotoxin β-N-methylamino-L-alanine (BMAA) is suspected to play a role in Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis. Because BMAA seems to be produced by cyanobacteria, surface waters are screened for BMAA. However, reliable analysis of BMAA requires specialized and expensive equipment. In 2012, a commercial enzyme-linked immunosorbent assay (ELISA) for determination of BMAA in surface waters was released. This kit could enable fast and relatively cheap screening of surface waters for BMAA. The objective of this study was to determine whether the BMAA ELISA kit was suitable for the determination of BMAA concentrations in surface waters. We hypothesised that the recovery of spiked samples was close to 100% and that the results of unspiked sample analysis were comparable between ELISA and liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis. However, we found that recovery was higher than 100% in most spiked samples, highest determined recovery was over 400%. Furthermore, the ELISA gave a positive signal for nearly each tested sample while no BMAA could be detected by LC-MS/MS. We therefore conclude that in its current state, the kit is not suitable for screening surface waters for BMAA.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0065260PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3676470PMC
January 2014

Dog poisonings associated with a Microcystis aeruginosa bloom in the Netherlands.

Toxins (Basel) 2013 Mar 14;5(3):556-67. Epub 2013 Mar 14.

Aquatic Ecology & Water Quality Management Group, Wageningen University, Wageningen, The Netherlands.

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 μg g(-1) dry-weight microcystin, the vomit of one of the dogs contained on average 94 µg microcystin g(-1) dry-weight. In both cases, microcystin-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.
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http://dx.doi.org/10.3390/toxins5030556DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3705278PMC
March 2013

A comparative study on three analytical methods for the determination of the neurotoxin BMAA in cyanobacteria.

PLoS One 2012 3;7(5):e36667. Epub 2012 May 3.

Department of Environmental Sciences, Wageningen University, Wageningen, The Netherlands.

The cyanobacterial neurotoxin β-N-methylamino-L-alanine (BMAA) has been considered a serious health threat because of its putative role in multiple neurodegenerative diseases. First reports on BMAA concentrations in cyanobacteria were alarming: nearly all cyanobacteria were assumed to contain high BMAA concentrations, implying ubiquitous exposure. Recent studies however question this presence of high BMAA concentrations in cyanobacteria. To assess the real risk of BMAA to human health, this discrepancy must be resolved. We therefore tested whether the differences found could be caused by the analytical methods used in different studies. Eight cyanobacterial samples and two control samples were analyzed by three commonly used methods: HPLC-FLD analysis and LC-MS/MS analysis of both derivatized and underivatized samples. In line with published results, HPLC-FLD detected relatively high BMAA concentrations in some cyanobacterial samples, while both LC-MS/MS methods only detected BMAA in the positive control (cycad seed sarcotesta). Because we could eliminate the use of different samples and treatments as causal factors, we demonstrate that the observed differences were caused by the analytical methods. We conclude that HPLC-FLD overestimated BMAA concentrations in some cyanobacterial samples due to its low selectivity and propose that BMAA might be present in (some) cyanobacteria, but in the low µg/g or ng/g range instead of the high µg/g range as sometimes reported before. We therefore recommend to use only selective and sensitive analytical methods like LC-MS/MS for BMAA analysis. Although possibly present in low concentrations in cyanobacteria, BMAA can still form a health risk. Recent evidence on BMAA accumulation in aquatic food chains suggests human exposure through consumption of fish and shellfish which expectedly exceeds exposure through cyanobacteria.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0036667PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3343013PMC
January 2013

First report of (homo)anatoxin-a and dog neurotoxicosis after ingestion of benthic cyanobacteria in The Netherlands.

Toxicon 2012 Sep 17;60(3):378-84. Epub 2012 Apr 17.

Aquatic Ecology & Water Quality Management Group, Wageningen University, P.O. Box 47, 6700 DD Wageningen, The Netherlands.

In April and May 2011, three dogs died and one dog became ill after swimming in Lake IJmeer (The Netherlands). At the time, the lake was infested with the benthic cyanobacterial species Phormidium. A Eurasian Coot (Fulica atra) and a Black-headed Gull (Chroicocephalus ridibundus) also died near Lake IJmeer in the same period. One of the dogs and both birds were subjected to a pathological investigation. Furthermore, the Phormidium mat; algal samples from the dikes; contents of the animals' digestive systems and organ tissues were analysed for the following cyanobacterial toxins: (homo)anatoxin-a; (7-deoxy-)cylindrospermopsin; saxitoxins and gonyautoxins by LC-MS/MS. Samples were also analysed for the nontoxic (homo)anatoxin-a metabolites dihydro(homo)anatoxin-a and epoxy(homo)anatoxin-a. The dog necropsy results indicated neurotoxicosis and its stomach contained Phormidium filaments. Anatoxin-a was detected in the Phormidium mat (272 μg g⁻¹) dry weight, stdev 65, n=3) and in the dog's stomach contents (9.5 μg g⁻¹ dry weight, stdev 2.4, n=3). Both samples also contained the anatoxin-a metabolite dihydroanatoxin-a, and a trace of homoanatoxin-a was detected in the Phormidium mat. The birds were in bad nutritive condition at the time of necropsy and their stomachs and intestines did not contain any cyanobacterial material. Furthermore, no cyanobacterial toxins were detected in their stomachs, intestines and organs and they both had lesions that are not associated with cyanobacterial intoxication. This is the first report of anatoxin-a and homoanatoxin-a occurrence in The Netherlands, these toxins have likely caused the deaths of three dogs. The birds probably died of other causes. Dutch recreational waters are at this moment only screened for pelagic cyanobacterial species, the current bathing water protocol therefore does not protect humans and animals from negative effects of blooms of benthic cyanobacteria.
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http://dx.doi.org/10.1016/j.toxicon.2012.04.335DOI Listing
September 2012

Recovery rates reflect distance to a tipping point in a living system.

Nature 2011 Dec 25;481(7381):357-9. Epub 2011 Dec 25.

Department of Aquatic Ecology and Water Quality Management, Wageningen University, PO Box 47, NL-6700 AA, Wageningen, The Netherlands.

Tipping points, at which complex systems can shift abruptly from one state to another, are notoriously difficult to predict. Theory proposes that early warning signals may be based on the phenomenon that recovery rates from small perturbations should tend to zero when approaching a tipping point; however, evidence that this happens in living systems is lacking. Here we test such 'critical slowing down' using a microcosm in which photo-inhibition drives a cyanobacterial population to a classical tipping point when a critical light level is exceeded. We show that over a large range of conditions, recovery from small perturbations becomes slower as the system comes closer to the critical point. In addition, autocorrelation in the subtle fluctuations of the system's state rose towards the tipping point, supporting the idea that this metric can be used as an indirect indicator of slowing down. Although stochasticity prohibits prediction of the timing of critical transitions, our results suggest that indicators of slowing down may be used to rank complex systems on a broad scale from resilient to fragile.
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http://dx.doi.org/10.1038/nature10723DOI Listing
December 2011

Controlling toxic cyanobacteria: effects of dredging and phosphorus-binding clay on cyanobacteria and microcystins.

Water Res 2012 Apr 13;46(5):1447-59. Epub 2011 Nov 13.

Aquatic Ecology & Water Quality Management Group, Department of Environmental Sciences, Wageningen University, P.O. Box 47, 6700 AA Wageningen, The Netherlands.

Sediment dredging and Phoslock(®) addition were applied individually and in combination in an enclosure experiment in a Dutch hypertrophic urban pond. These measures were applied to control eutrophication and reduce the risk of exposure to cyanobacterial toxins. Over the 58 days course of the experiment, cyanobacteria (predominantly Microcystis aeruginosa) gradually decreased until they dropped below the level of detection in the combined treated enclosures, they were reduced in dredged enclosures, but remained flourishing in controls and Phoslock(®) treated enclosures. Cyanobacteria were, however, less abundant in the enclosures (medians chlorophyll-a 30-87 μg l(-1)) than in the pond (median chlorophyll-a 162 μg l(-1)), where also a thick surface scum covered one-third of the pond for many weeks. Soluble reactive phosphorus (SRP), total phosphorus and total nitrogen concentrations were significantly lower in the combined dredged and Phoslock(®) treated enclosures than in controls. Median SRP concentrations were 24 μg P l(-1) in the combined treatment, 58 μg P l(-1) in dredged enclosures, and 90 μg P l(-1) in controls and 95 μg P l(-1) in Phoslock(®) treated enclosures. Hence, the combined treatment was most effective in decreasing SRP and TP, and in lowering cyanobacterial biomass. Microcystin (MC) concentrations were analyzed by LC-MS/MS. MC concentrations and cyanobacterial biomass were positively correlated in all treatments. Mean MC concentrations in controls (71 μg l(-1)), Phoslock(®) treated enclosures (37 μg l(-1)) and dredged enclosures (25 μg l(-1)) exceeded the provisional guideline of 20 μg l(-1), whereas mean MC concentrations were 13 μg l(-1) in the combined treated enclosures. All samples contained the MC variants dmMC-RR, MC-RR, MC-YR, dmMC-LR and MC-LR; traces of MC-LY and nodularin were detected in few samples. The different treatments did not change the relative contribution of the variants to the MC pool; MC profiles in all treatments and the pond showed dominance of MC-RR followed by MC-LR. In the surface scum of the pond, total MC concentration was extremely high (64000 μg l(-1) or 1300 μg g(-1) DW), which poses a serious health hazard to children playing on the banks of the pond. Based on our results and pond characteristics, we propose combined sediment dredging and Phoslock(®) addition, fish removal and strong reduction of duck feeding by the neighborhood as most promising measures controlling cyanobacterial hazards in this pond.
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http://dx.doi.org/10.1016/j.watres.2011.11.008DOI Listing
April 2012

Determination of the neurotoxins BMAA (beta-N-methylamino-L-alanine) and DAB (alpha-,gamma-diaminobutyric acid) by LC-MSMS in Dutch urban waters with cyanobacterial blooms.

Amyotroph Lateral Scler 2009 ;10 Suppl 2:79-84

Department of Environmental Sciences, Wageningen University and Research Centre, Wageningen, The Netherlands.

We aimed to determine concentrations of the neurotoxic amino acids beta-N-methylamino-L-alanine (BMAA) and alpha-,gamma-diaminobutyric acid (DAB) in mixed species scum material from Dutch urban waters that suffer from cyanobacterial blooms. BMAA and DAB were analysed in scum material without derivatization by LC-MSMS (liquid chromatography coupled to tandem mass spectrometry) using hydrophilic interaction chromatography (HILIC). Our method showed high selectivity, good recovery of added compounds after sample extraction (86% for BMAA and 85% for DAB), acceptable recovery after sample hydrolysation (70% for BMAA and 56% for DAB) and acceptable precision. BMAA and DAB could be detected at an injected amount of 0.34 pmol. Free BMAA was detected in nine of the 21 sampled locations with a maximum concentration of 42 microg/g DW. Free DAB was detected in two locations with a maximum concentration of 4 microg/g DW. No protein-associated forms were detected. This study is the first to detect underivatized BMAA in cyanobacterial scum material using LC-MSMS. Ubiquity of BMAA in cyanobacteria scums of Dutch urban waters could not be confirmed, where BMAA and DAB concentrations were relatively low; however, co-occurrence with other cyanobacterial neurotoxins might pose a serious health risk including chronic effects from low-level doses.
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http://dx.doi.org/10.3109/17482960903272967DOI Listing
March 2010

Real-time automated measurement of Xenopus leavis tadpole behavior and behavioral responses following triphenyltin exposure using the multispecies freshwater biomonitor (MFB).

Aquat Toxicol 2006 May 20;77(3):298-305. Epub 2006 Feb 20.

Toxicology Section, Wageningen University, Tuinlaan 5, 6703 HE Wageningen, The Netherlands.

The present study examines whether behavior of Xenopus laevis tadpoles, when measured with the multispecies freshwater biomonitor (MFB), can be a sensitive and practical parameter for quantification of behavioral effects induced by toxic compounds. The MFB system is capable of automated simultaneous recording and integration of different types of movement over time. Basic tadpole behavior was studied under standard ambient temperature and colder conditions. At lower temperatures the time spent on low frequency behavior such as swimming and ventilation decreased, while at higher frequency movements associated with subtle tail tip oscillations it increased. Changes in behavior were also studied during the process of metamorphosis when both the morphology and physiology of tadpoles change. In the course of metamorphosis the tadpoles decreased the time spent on swimming and increased tail tip oscillations, especially in the period shortly before and during metamorphic climax. Additional experiments were performed to investigate whether the MFB could be used to quantify behavioral effects of exposure to a toxic compound. A 48 h exposure to a sublethal concentration of 1.25 microg L(-1) triphenyltin (TPT) significantly increased low frequency behavior, whereas 5 microg L(-1) TPT significantly reduced this type of behavior while the number of periods of total inactivity increased. One week after transferring the animals to clean water, registered behavior of tadpoles in the highest TPT group (5 microg L(-1)) was normal again for this developmental stage. The results show that the MFB can be used as a new tool for automated registration of sublethal toxic effects on tadpole behavior including recovery.
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http://dx.doi.org/10.1016/j.aquatox.2005.12.011DOI Listing
May 2006

T-screen to quantify functional potentiating, antagonistic and thyroid hormone-like activities of poly halogenated aromatic hydrocarbons (PHAHs).

Toxicol In Vitro 2006 Jun 10;20(4):490-8. Epub 2005 Oct 10.

Department of Toxicology, Toxicology Section, Wageningen University, Tuinlaan 5, 6703 HE Wageningen, The Netherlands.

The present study investigates chemical thyroid hormone disruption at the level of thyroid hormone receptor (TR) functioning. To this end the (ant)agonistic action of a series of xenobiotics was tested in the newly developed T-screen. This assay makes use of a GH3 rat pituitary cell line, that specifically proliferates when exposed to 3,3',5-triiodo-L-thyronine (T3). The growth stimulatory effect is mediated via T3-receptors. (Ant)agonistic and potentiating action of compounds was studied in absence and presence of T3 at its EC50 level (0.25 nM). The compounds tested included the specific TR-antagonist amiodarone, as well as a series of brominated diphenyl ethers (BDEs), including specifically synthesized BDEs with a structural resemblance to 3,5-diiodo-L-thyronine (T2), T3 and T4 (3,3',5,5'-tetraiodo-L-thyronine). The results obtained reveal that only BDE206 and amiodarone are specific antagonists. Interestingly some compounds which did not respond in the T-screen in absence of T3, potentiated effects when tested in combination with T3. This points at possibilities for disruption at the TR in vivo, where exposure generally occurs in presence of T3. Altogether the results of the present study show that the newly developed T-screen can be used as a valuable tool for identification and quantification of compounds active in disturbing thyroid hormone homeostasis at the level of TR-functioning.
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http://dx.doi.org/10.1016/j.tiv.2005.09.001DOI Listing
June 2006
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