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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Usability of the bivalves Dreissena polymorpha and Anodonta anatina for a biosurvey of the neurotoxin BMAA in freshwater ecosystems
Lepoutre, A. ; Hervieux, J. ; Faassen, E.J. ; Zweers, A.J. ; Lurling, M. ; Geffard, A. ; Lance, E. - \ 2020
Environmental Pollution 259 (2020). - ISSN 0269-7491
Anodonta anatina - Bioaccumulation - Biosurvey - Dreissena polymorpha - β-Methylamino-L-alanine

The environmental neurotoxin β-methylamino-L-alanine (BMAA) may represent a risk for human health in case of chronic exposure or after short-term exposure during embryo development. BMAA accumulates in freshwater and marine organisms consumed by humans. It is produced by marine and freshwater phytoplankton species, but the range of producers remains unknown. Therefore, analysing the phytoplankton composition is not sufficient to inform about the risk of freshwater contamination by BMAA. Filter-feeders mussels have accumulation capacities and therefore appear to be relevant to monitor various pollutants in aquatic ecosystems. We investigated the suitability of the freshwater mussels Dreissena polymorpha and Anodonta anatina for monitoring BMAA in water. Both species were exposed to 1, 10, and 50 μg of dissolved BMAA/L daily for 21 days, followed by 42 days of depuration in clean water. On days 0, 1, 7, 14, and 21 of exposure and 1, 7, 14, 21 and 42 of depuration, whole D. polymorpha and digestive glands of A. anatina were sampled, and the total BMAA concentration was measured. D. polymorpha accumulated BMAA earlier (from day 1 at all concentrations) and at higher tissue concentrations than A. anatina, which accumulated BMAA from day 14 when exposed to 10 μg BMAA/L and from day 7 when exposed to 50 μg BMAA/L. As BMAA accumulation by D. polymorpha was time and concentration-dependent, with a significant elimination during the depuration period, this species may be able to reflect the levels and dynamics of water contamination by dissolved BMAA. The species A. anatina could be used for monitoring water concentrations above 10 μg BMAA/L. D. polymorpha and A. anatina could be used to biomonitor BMAA in fresh water.

Lanthanum in Water, Sediment, Macrophytes and chironomid larvae following application of Lanthanum modified bentonite to lake Rauwbraken (The Netherlands)
Oosterhout, Frank van; Waajen, Guido ; Yasseri, Said ; Manzi Marinho, Marcelo ; Pessoa Noyma, Natália ; Mucci, Maíra ; Douglas, Grant ; Lürling, Miquel - \ 2020
Science of the Total Environment 706 (2020). - ISSN 0048-9697
Bioavailable - Filterable lanthanum - Lake management - Phoslock® - Sediment release

Lanthanum Modified Bentonite (LMB; Phoslock®) is used to mitigate eutrophication by binding phosphate released from sediments. This study investigated the fate of lanthanum (La) from LMB in water, sediment, macrophytes, and chironomid larvae in Lake Rauwbraken (The Netherlands). Before the LMB application, water column filterable La (FLa) was 0.02 µg L−1, total La (TLa) was 0.22 µg L−1. In sediment the total La ranged 0.03–1.86 g m−2. The day after the application the maximum FLa concentration in the water column was 44 µg L−1, TLa was 528 µg L−1, exceeding the Dutch Maximum Permissible Concentrations (MPC) of 10.1 µg L−1 by three to fourfold. TLa declined below the MPC after 15 days, FLa after 75 days. After ten years, FLa was 0.4 µg L−1 and TLa was 0.7 µg L−1. Over the post-application years, FLa and TLa showed statistically significant downward trends. While the LMB settled homogeneously on sediment, after 3 years it redistributed to 0.2–5.4 g La m−2 within shallow zones, and 30.7 g m−2 to 40.0 g La m−2 in deeper zones. In the upper 20 cm of sediment, La concentrations were 7–6702 mg kg −1 dry weight (DW) compared to 0.5–7.0 mg kg−1 before application. Pre-application anaerobic sediment release of FLa was 0.006 mg m−2 day−1. Three months after the application it was 1.02 mg m−2 day−1. Three years later it was 0.063 mg m−2 day−1. Before application La in plants was 0.8–5.1 mg La kg−1 DW, post-application values were up to 2925 mg La kg−1 DW. In chironomid larvae, La increased from 1.7 µg g−1 DW before application to 1421 µg g−1 DW after one month, 3 years later it was 277 µg g−1 DW. Filtration experiments indicate FLa is not truly dissolved free La3+ cations.

Comment on: Svatos, K.B.W. (2018). “Commercial silicate phosphate sequestration and desorption leads to a gradual decline of aquatic systems” by Environ
Douglas, Grant ; Rate, Andrew ; Lurling, Miquel - \ 2019
Environmental Science and Pollution Research (2019). - ISSN 0944-1344
Kun je zwemmen in water met blauwalg?
Lurling, Miguel - \ 2019
Hoe bedwing je de giftige drab?
Lurling, Miguel - \ 2019
Intraspecific variability in response to phosphorus depleted conditions in the cyanobacteria Microcystis aeruginosa and Raphidiopsis raciborskii
Guedes, Iame Alves ; Pacheco, Ana Beatriz F. ; Vilar, Mauro C.P. ; Mello, Mariana M. ; Marinho, Marcelo Manzi ; Lurling, Miquel ; Azevedo, Sandra M.F.O. - \ 2019
Harmful Algae 86 (2019). - ISSN 1568-9883 - p. 96 - 105.
Cylindrospermopsis - Ecotypes - Phosphorus uptake - Strain variability

Phosphorus loading plays an important role in the occurrence of cyanobacterial blooms and understanding how this nutrient affects the physiology of cyanobacteria is imperative to manage these phenomena. Microcystis aeruginosa and Raphidiopsis raciborskii are cyanobacterial species that form potentially toxic blooms in freshwater ecosystems worldwide. Blooms comprise numerous strains with high trait variability, which can contribute to the widespread distribution of these species. Here, we explored the intraspecific variability in response to phosphorus depleted conditions (P-)testing five strains of each species. Strains could be differentiated by cell volume or genetic profiles except for those of the same species, sampling location and date, though these presented differences in their response to (P-). Although differently affected by (P-)over 10 days, all strains were able to grow and maintain photosynthetic activity. For most M. aeruginosa and R. raciborskii strains growth rates were not significantly different comparing (P+)and (P-)conditions. After ten days in (P-), only one M. aeruginosa strain and two R. raciborskii strains showed reduction in biovolume yield as compared to (P+)but in most strains chlorophyll-a concentrations were lower in (P-)than in (P+). Reduced photosystem II efficiency was found for only one R. raciborskii strain while all M. aeruginosa strains were affected. Only two M. aeruginosa and one R. raciborskii strain increased alkaline phosphatase activity under (P-)as compared to (P+). Variation in P-uptake was also observed but comparison among strains yielded homogeneous groups comprised of representatives of both species. Comparing the response of each species as a whole, the (P-)condition affected growth rate, biovolume yield and chlorophyll yield. However, these parameters revealed variation among strains of the same species to the extent that differences between M. aeruginosa and R. raciborskii were not significant. Taken together, these results do not support the idea that R. raciborskii, as a species, can withstand phosphorus limitation better than M. aeruginosa and also point that the level of intraspecific variation may preclude generalizations based on studies that use only one or few strains.

Seasonal and diel variation in greenhouse gas emissions from an urban pond and its major drivers
Bergen, Tamara van; Barros, Nathan O. ; Mendonça, Raquel ; Aben, Ralf ; Althuizen, Inge H.J. ; Moraes Huszar, Vera Lúcia de; Lamers, Leon P.M. ; Lurling, M.F.L.L.W. ; Roland, Fabio ; Kosten, Sarian - \ 2019
Limnology and Oceanography 64 (2019)5. - ISSN 0024-3590 - p. 2129 - 2139.
Small water systems are important hotspots of greenhouse gas (GHG) emission, but estimates are poorly constrained as data are scarce. Small ponds are often constructed in urban areas, where they receive large amounts
of nutrients and therefore tend to be highly productive. Here, we investigated GHG emissions, seasonal and diel
variation, and net ecosystem production (NEP) from an urban pond. In monthly 24-h field campaigns during
11 months, diffusive water–atmosphere methane (CH4) and carbon dioxide (CO2) fluxes and CH4 ebullition
and oxidation were quantified. With oxygen (O2) measurements, NEP was assessed. The pond was a net GHG
source the entire year, with an emission of 3.4 kg CO2 eq m−2 yr−1
. The dominant GHG emission pathway was
CH4 ebullition (bubble flux, 50%), followed by diffusive emissions of CO2 (38%) and CH4 (12%). Sediment CH4
release was primarily driven by temperature and especially ebullition increased exponentially above a temperature threshold of 15C. The pond’s atmospheric CO2 exchange was not related to NEP or temperature but likely
to a high allochthonous carbon (C) input via runoff and anaerobic mineralization of C. We expect urban ponds
to show a large increase in GHG emission with increasing temperature, which should be considered carefully
when constructing ponds in urban areas. Emissions may partly be counteracted by pond management focusing
on a reduction of nutrient and organic matter input.
Zooplankton grazing selectivity regulates herbivory and dominance of toxic phytoplankton over multiple prey generations
Ger, Kemal Ali ; Naus-Wiezer, Suzanne ; Meester, Luc De; Lürling, Miquel - \ 2019
Limnology and Oceanography 64 (2019)3. - ISSN 0024-3590 - p. 1214 - 1227.

How grazer selectivity regulates the primary producer community is a core topic in ecology. Yet, the role of zooplankton grazing selection on phytoplankton dynamics is poorly understood. Few studies have compared the effect of grazers with contrasting selectivity on mixed phytoplankton prey, and none over multiple phytoplankton generations. We tested the hypothesis that a selectively grazing copepod (Eudiaptomus gracilis) would facilitate the dominance of a toxic cyanobacterium (Microcystis aeruginosa) by grazing on a competing eukaryotic microalga (Cryptomonas pyrenoidifera), while a generalist cladoceran (Daphnia magna) would have no effect on the dominance of cyanobacteria in 4-d laboratory cocultures. Experiments started with a ninefold initial dominance of Cryptomonas over Microcystis by biomass. Each grazer type was added to cocultured phytoplankton and the abundance of phytoplankton was compared to no-grazer controls. As predicted, Daphnia had no effect on the relative abundance of its prey and the copepod facilitated Microcystis dominance, although the strength of facilitation slightly declined with time. As the copepod reduced mostly the biomass of the edible algae, it pushed the system toward the dominance of toxic prey, which likely reduced the efficiency of selective grazing on the last day. Hence, while the selective grazer promoted cyanobacterial dominance, the effect may be weaker than predicted from extrapolating grazing rates obtained from short-term (i.e., hourly) assays. Overall, predicting the role of zooplankton selectivity on phytoplankton dynamics—especially harmful algal blooms—would benefit from accounting for fluctuations in grazer effects due to shifting abundance and growth of each prey over time.

From green to transparent waters : Managing eutrophication and cyanobacterial blooms by geo-engineering
Mucci, Maíra N.T. - \ 2019
Wageningen University. Promotor(en): M.F.L.L.W. Lürling, co-promotor(en): E.J. Faassen; M. Manzi. - Wageningen : Wageningen University - ISBN 9789463434416 - 200

Eutrophication and cyanobacterial blooms are increasing worldwide. Despite being studied for almost a century, mitigating eutrophication remains a challenge. Motivated by this challenge, we studied potential geo-engineering materials and in-site techniques to manage the eutrophication and cyanobacterial blooms in controlled experiments and a whole-ecosystem intervention.

As phosphorus (P) control is essential to manage eutrophication, this thesis started evaluating natural and modified clays and soils for their capacity to adsorb P (chapter 2). We showed that four out of ten materials were able to adsorb P, and that P adsorption differed under varying abiotic conditions. The modified materials (lanthanum (La) modified bentonite, commercially called Phoslock® and Aluminium modified zeolite, commercially called Aqual-P®) were able to adsorb more P than the naturals ones such as Fe-rich soils

The need to mitigate eutrophication in coastal areas prompted us to evaluate Phoslock® efficiency and behaviour in saline waters in chapter 3. Phoslock® was able to adsorb P in all salinities tested from brackish to seawater, whilst filterable La concentrations remained very low. We concluded that the use of Phoslock® on saline waters should be considered, yet, ecotoxicological studies must be performed before field applications in saline environments.

Beside solid-phase P sorbents, flocculants have also been used in lake restoration. In this context, chitosan has been proposed as an “eco-friendly” flocculant as an alternative to metal based flocculant, such as polyaluminium chloride (PAC). In chapter 4, we tested the effect of chitosan on several cyanobacterial species and showed that chitosan may cause rapid cell lysis. In chapter 5, we looked closer into strain variation whilst also measuring cyanotoxin release. We showed that chitosan was able to cause cyanotoxins release. These effects were, however, strain dependent. Chitosan application might therefore cause toxin release in the water column, and it should not therefore be used without testing its effects on the cyanobacterial assemblage being targeted to avoid unwanted rapid release of cyanotoxins.

In chapter 6, we showed field results from a whole-lake treatment with PAC and Phoslock®. This technique called Flock and Lock aimed to target P from the water column, P-release from the sediment and the ongoing cyanobacterial bloom. The intervention was successful in improving water quality in Lake De Kuil. After two

weeks of the treatment, however a surface scum was observed near the shore of the lake, which disappeared spontaneously after two weeks. The lake was open in time for the bathing season without any swimming bans during 2017. Tests to why the scums occurred, and how to avoid their occurrence showed that promising approach to avoid biomass accumulation is to damage the cell first using hydrogen peroxide and later settle them with the Flock and Lock technique. Larger scales tests need still to be performed to shed light on possible limitations of this technique.

In chapter 7 I reflected that there is no single magical solution to manage eutrophication and cyanobacterial blooms. Each system is unique and each material/technique (P immobilization, chitosan, Flock and Lock, peroxide) has its limitations. Thus, a broad-scale generalization (copy-paste of methods) will in most cases not lead to a successful restoration. A mitigation plan must always include a proper system analysis and experimental tests under realistic condition on various scales before a field application can be performed.

Composition of dissolved organic matter controls interactions with La and Al ions : Implications for phosphorus immobilization in eutrophic lakes
Du, Yingxun ; Zhang, Qiaoying ; Liu, Zhengwen ; He, Hu ; Lürling, Miquel ; Chen, Musong ; Zhang, Yunlin - \ 2019
Environmental Pollution 248 (2019). - ISSN 0269-7491 - p. 36 - 47.
Al - Dissolved organic matter - EEM-PARAFAC - Interaction - La - Phosphorus immobilization

Applications of aluminium (Al) salt or lanthanum (La) modified bentonite (LMB) have become popular methodologies for immobilizing phosphorus (P) in eutrophic lakes. The presence of humic substances, has been shown to inhibit this form of treatment due to the complexation with La/Al. However, the effects of other dissolved organic matter (DOM), especially that derived from phytoplankton (the dominant source in eutrophic lakes) are unknown. In this study, the interaction with La/Al of Suwannee River Standard Humic Acid Standard II (SRHA) and algae-derived DOM (ADOM) were investigated and compared. Differed to SRHA which was dominated by polyphenol-like component (76.8%, C1-SRHA), majority in ADOM were protein-like substance, including 41.9% tryptophan-like component (C2-ADOM) and 21.0% tyrosine-like component (C3-ADOM). Two reactions of complexation and coprecipitation were observed between SRHA/ADOM and La/Al. Complexation dominated at low metal inputs less than 10 μM and coprecipitation was the main reaction at higher metal inputs. For ADOM, the tryptophan-like component (C2-ADOM) was the important component to react with metal. The reaction rate for C2-ADOM with La were about two-third of that for C1-SRHA, indicating that the influence of C2-ADOM was significant during the P immobilization by La/Al-based treatment in eutrophic lakes. The P removal data in the presence of ADOM confirmed the significant inhibition of ADOM. In addition, based on the composition of coprecipitates and relatively biodegradable character of tryptophan-like substances (C2-ADOM), the coprecipitation of ADOM was assumed to reduce the stability of precipitated P in eutrophic lakes. The release of P from the potential biodegradation of the coprecipitates and thus the possible decline of the performance of P immobilization by La/Al-based treatments is an important work in the future.

Combined Effect of Light and Temperature on the Production of Saxitoxins in Cylindrospermopsis raciborskii Strains
Mesquita, Marcella C.B. ; Lürling, Miquel ; Dorr, Fabiane ; Pinto, Ernani ; Marinho, Marcelo M. - \ 2019
Toxins 11 (2019)1. - ISSN 2072-6651 - 15 p.
cyanobacteria - cyanotoxins - intraspecific variability - saxitoxins

Cylindrospermopsis raciborskii is a potentially toxic freshwater cyanobacterium that can tolerate a wide range of light and temperature. Due to climatic changes, the interaction between light and temperature is studied in aquatic systems, but no study has addressed the effect of both variables on the saxitoxins production. This study evaluated the combined effect of light and temperature on saxitoxins production and cellular quota in C. raciborskii. Experiments were performed with three C. raciborskii strains in batch cultures under six light intensities (10, 40, 60, 100, 150, and 500 μmol of photons m-2 s-1) and four temperatures (15, 20, 25, and 30 °C). The growth of C. raciborskii strains was limited at lower temperatures and the maximum growth rates were obtained under higher light combined with temperatures equal or above 20 °C, depending on the strain. In general, growth was highest at 30 °C at the lower light intensities and equally high at 25 °C and 30 °C under higher light. Highest saxitoxins concentration and cell-quota occurred at 25 °C under high light intensities, but were much lower at 30 °C. Hence, increased temperatures combined with sufficient light will lead to higher C. raciborskii biomass, but blooms could become less toxic in tropical regions.

Human health risk associated with the management of phosphorus in freshwaters using lanthanum and aluminium
haese, P.C. D'; Douglas, G. ; A., Verhulst ; Neven, E. ; Behets, G.J. ; Vervaet, B.A. ; Finsterle, K. ; Lurling, M.F.L.L.W. - \ 2019
Chemosphere 220 (2019). - ISSN 0045-6535 - p. 286 - 299.
The use of geo-engineering materials to manage phosphorus in lakes has increased in recent years with aluminium and lanthanum based materials being most commonly applied. Hence the potential impact of the use of these compounds on human health is receiving growing interest. This review seeks to understand, evaluate and compare potential unintended consequences on human health and ecotoxicological risks associated with the use of lanthanum- and aluminium-based materials to modify chemical and ecological conditions in water bodies. In addition to their therapeutic use for the reduction of intestinal phosphate absorption in patients with impaired renal function, the phosphate binding capacity of aluminium and lanthanum also led to the development of materials used for water treatment. Although lanthanum and aluminium share physicochemical similarities and have many common applications, their uptake and kinetics within the human body and living organisms importantly differ from each other which is reflected in a different toxicity profile. Whilst a causal role in the development of neurological pathologies, skeletal lesions, hematopoietic disorders and respiratory effects has unequivocally been demonstrated with increased exposure to aluminium, studies until now have failed to find such a clear association after exposure to lanthanum although caution is warranted. Our review indicates that lanthanum and aluminium have a distinctly different profile with respect to their potential effects on human health. Regular monitoring of both aluminium and lanthanum concentrations in lanthanum-/aluminium-treated water by the responsible authorities is recommended to avoid acute accidental or chronic low level accumulation.
Towards restoring urban waters : understanding the main pressures
Teurlincx, Sven ; Kuiper, Jan J. ; Hoevenaar, Ellen C.M. ; Lurling, Miquel ; Brederveld, Robert J. ; Veraart, Annelies J. ; Janssen, Annette B.G. ; Mooij, Wolf M. ; Senerpont Domis, Lisette N. de - \ 2019
Current Opinion in Environmental Sustainability 36 (2019). - ISSN 1877-3435 - p. 49 - 58.

Water bodies in the urban landscape are omnipresent, with many being small, lentic waters such as ponds and lakes. Because of high anthropogenic forcing, these systems have poor water quality, with large consequences for the provisioning of ecosystem services. Understanding of the main pressures on urban water quality is key to successful management. We identify six pressures that we hypothesize to have strong links to anthropogenic forcing including: eutrophication, aquatic invasive species, altered hydrology, altered habitat structure, climate change, and micropollutants. We discuss how these pressures may affect water quality and ecological functioning of urban waters. We describe how these pressures may interact, posing challengers for water management. We identify steps that need to be taken towards sustainable restoration, recognizing the challenges that potentially interacting pressures pose to water managers.

Managing Eutrophication in a Tropical Brackish Water Lagoon : Testing Lanthanum-Modified Clay and Coagulant for Internal Load Reduction and Cyanobacteria Bloom Removal
Magalhães, Leonardo de; Noyma, Natalia Pessoa ; Furtado, Luciana Lima ; Drummond, Erick ; Leite, Vivian Balthazar Gonçalves ; Mucci, Maíra ; Oosterhout, Frank van; Moraes Huszar, Vera Lúcia de; Lürling, Miquel ; Marinho, Marcelo Manzi - \ 2019
Estuaries and coasts 42 (2019)2. - ISSN 1559-2723 - p. 390 - 402.
Geo-engineering - Lake restoration - PAC - Phoslock - Phosphorus control - Sediment release

The release of phosphorus (P) stored in the sediment may cause long-term delay in the recovery of lakes, ponds, and lagoons from eutrophication. In this paper, we tested on a laboratory scale the efficacy of the flocculant polyaluminium chloride (PAC) and a strong P-binding agent (lanthanum-modified bentonite, LMB) on their ability to flocculate a cyanobacterial bloom and hamper P release from a hypertrophic, brackish lagoon sediment. In addition, critical P loading was estimated through PCLake. We showed that cyanobacteria could be effectively settled using a PAC dose of 2 mg Al L−1 combined with 400-mg L−1 LMB; PAC 8 mg Al L−1 alone could also remove cyanobacteria, although its performance was improved adding low concentrations of LMB. The efficacy of LMB to bind P released from the sediment was tested based on potentially available sediment P. A dose of 400 g LMB m−2 significantly reduced the P release from sediment to over-standing water (either deionized water or water from the lagoon with and without cyanobacteria). In sediment cores, LMB + PAC reduced sediment P flux from 9.9 (± 3.3) to − 4.6 (± 0.3) mg P m−2 day−1 for the experimental period of 3 months. The internal P load was 14 times higher than the estimated P critical load (0.7 mg P m−2 day−1), thus even if all the external P sources would be ceased, the water quality will not improve promptly. Hence, the combined LMB + PAC treatment seems a promising in-lake intervention to diminish internal P load bellow the critical load. Such intervention is able to speed up recovery in the brackish lagoon once external loading has been tackled and at a cost of less than 5% of the estimated dredging costs.

The unfulfilled promise of urban Lake Kleine Melanen (The Netherlands) : Diagnostics, experiment on reduction of sediment P-release and in-lake restoration
Waajen, Guido ; Lürling, Miquel ; Sande, René van de - \ 2019
Lake and Reservoir Management 35 (2019)1. - ISSN 1040-2381 - p. 8 - 24.
Biomanipulation - cyanobacteria - eutrophication management - Phoslock - polyaluminumchloride - sediment capping - stormwater runoff

Lake Kleine Melanen (The Netherlands) experienced cyanobacterial blooms during the summertime, causing public health risks, turbid water, and lack of macrophytes. To improve the situation, we determined the underlying causes of the poor water quality. Our diagnosis included the water and phosphorus (P) budget of the lake and showed the need for the reduction of both the external and internal P loads. The external P load (7.5 mg P/m2/d) exceeded the transition between the clear water state and the turbid state by 44–121%, mainly due to the discharges from the separated stormwater sewer system in the adjacent neighborhood. Due to political and financial considerations of the managing authorities, the restoration (2010–2012) was restricted to internal management. To reduce the high internal P load (3.8 mg P/m2/d), we tested 3 sediment capping options in an enclosure experiment, showing the best results when we combined sand capping with the P fixative Phoslock® and flocculant polyaluminumchloride. A 0.6–1.3 m thick layer of soft sediment was dredged from the lake. Thereafter, the sediment was capped with a 0.2 m thick layer of sand to which Phoslock® was added. Additional in-lake measures including fish removal and shoreline reconstruction were also conducted to support improvement. We compared water quality before (2008–2010) and after (2012–2014) interventions. Although the mean concentration of total P was reduced from 0.30 to 0.11 mg P/L, and cyanobacterial chlorophyll a from 52 to 6 μg/L, cyanobacterial blooms still occurred. For further water quality improvement, the reduction of the external P load caused by stormwater runoff is required.

Cyanobacterial Blooms and Microcystins in Southern Vietnam
Trung, Bui ; Dao, Thanh Son ; Faassen, Elisabeth ; Lürling, Miquel - \ 2018
Toxins 10 (2018)11. - ISSN 2072-6651
aquaculture - cyanobacteria - cyanotoxins - Mekong river

Studies on cyanobacteria in Vietnam are limited and mainly restricted to large reservoirs. Cyanobacterial blooms in small water bodies may pose a health risk to local people. We sampled 17 water bodies in the vicinity of urban settlements throughout the Mekong basin and in southeast Vietnam. From these, 40 water samples were taken, 24 cyanobacterial strains were isolated and 129 fish, 68 snail, 7 shrimp, 4 clam, and 4 duck samples were analyzed for microcystins (MCs). MCs were detected up to 11,039 µg/L or to 4033 µg/g DW in water samples. MCs were detected in the viscera of the animals. MC-LR and MC-RR were most frequently detected, while MC-dmLR, MC-LW, and MC-LF were first recorded in Vietnam. Microcystis was the main potential toxin producer and the most common bloom-forming species. A potential health hazard was found in a duck⁻fish pond located in the catchment of DauTieng reservoir and in the DongNai river where raw water was collected for DongNai waterwork. The whole viscera of fish and snails must be completely removed during food processing. Cyanobacterial monitoring programs should be established to assess and minimize potential public health risks.

A European Multi Lake Survey dataset of environmental variables, phytoplankton pigments and cyanotoxins
Mantzouki, E. ; Campbell, J. ; Loon, E. van; Visser, P. ; Konstantinou, I. ; Antoniou, M. ; Giuliani, G. ; Machado-Vieira, D. ; Gurjão de Oliveira, A. ; Maronić, D.Š. ; Stević, F. ; Pfeiffer, T.Ž. ; Vucelić, I.B. ; Žutinić, P. ; Udovič, M.G. ; Plenković-Moraj, A. ; Tsiarta, N. ; Bláha, L. ; Geriš, R. ; Fránková, M. ; Christoffersen, K.S. ; Warming, T.P. ; Feldmann, T. ; Laas, A. ; Panksep, K. ; Tuvikene, L. ; Kangro, K. ; Häggqvist, K. ; Salmi, P. ; Arvola, L. ; Fastner, J. ; Straile, D. ; Rothhaupt, K.O. ; Fonvielle, J. ; Grossart, H.P. ; Avagianos, C. ; Kaloudis, T. ; Triantis, T. ; Zervou, S.K. ; Hiskia, A. ; Gkelis, S. ; Panou, M. ; McCarthy, V. ; Senerpont Domis, L.N. de; Seelen, L. ; Verstijnen, Y. ; Lürling, M. ; Maliaka, V. ; Faassen, E.J. - \ 2018
Scientific Data 5 (2018). - ISSN 2052-4463 - 13 p.
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.
Response of natural cyanobacteria and algae assemblages to a nutrient pulse and elevated temperature
Lürling, Miquel ; Mello, Mariana Mendese ; Oosterhout, Frank van; Senerpont Domis, Lisette de; Marinho, Marcelo M. - \ 2018
Frontiers in Microbiology 9 (2018)AUG. - ISSN 1664-302X
Blooms - Climate change - Competition - Global warming - Optimum growth

Eutrophication (nutrient over-enrichment) is the primary worldwide water quality issue often leading to nuisance cyanobacterial blooms. Climate change is predicted to cause further rise of cyanobacteria blooms as cyanobacteria can have a competitive advantage at elevated temperatures. We tested the hypothesis that simultaneous rise in nutrients and temperature will promote cyanobacteria more than a single increase in one of the two drivers. To this end, controlled experiments were run with seston from 39 different urban water bodies varying in trophic state from mesotrophic to hypertrophic. These experiments were carried out at two different temperatures, 20°C (ambient) and 25°C (warming scenario) with or without the addition of a surplus of nutrients (eutrophication scenario). To facilitate comparisons, we quantified the effect size of the different treatments, using cyanobacterial and algal chlorophyll a concentrations as a response variable. Cyanobacterial and algal chlorophyll a concentrations were determined with a PHYTO-PAM phytoplankton analyzer. Warming caused an 18% increase in cyanobacterial chlorophyll-α, while algal chlorophyll-α concentrations were on average 8% higher at 25°C than at 20°C. A nutrient pulse had a much stronger effect on chlorophyll-α concentrations than warming. Cyanobacterial chlorophyll-α concentrations in nutrient enriched incubations at 20 or 25°C were similar and 9 times higher than in the incubations without nutrient pulse. Likewise, algal chlorophyll-α concentrations were 6 times higher. The results of this study confirm that warming alone yields marginally higher cyanobacteria chlorophyll-α concentrations, yet that a pulse of additional nutrients is boosting blooms. The responses of seston originating from mesotrophic waters seemed less strong than those from eutrophic waters, which indicates that nutrient control strategies -catchment as well as in-system measures- could increase the resilience of surface waters to the negative effects of climate change.

The impact of warming and nutrients on algae production and microcystins in seston from the iconic lake lesser Prespa, Greece
Maliaka, Valentini ; Faassen, Elisabeth J. ; Smolders, Alfons J.P. ; Lürling, Miquel - \ 2018
Toxins 10 (2018)4. - ISSN 2072-6651
Bioassay - Climate change - Cyanotoxins - Eutrophication - Nutrient addition
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.
Temperature Effects Explain Continental Scale Distribution of Cyanobacterial Toxins
Lurling, M.F.L.L.W. ; Senerpont Domis, Lisette de; Seelen, Laura ; Verstijnen, Yvon ; Maliaka, Valentini ; Fastner, Jutta ; Teurlincx, Sven - \ 2018
Toxins 10 (2018)4. - ISSN 2072-6651
Insight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their potency. Most studies examine the relationship between individual toxin variants and environmental factors, such as nutrients, temperature and light. In summer 2015, we collected samples across Europe to investigate the effect of nutrient and temperature gradients on the variability of toxin production at a continental scale. Direct and indirect effects of temperature were the main drivers of the spatial distribution in the toxins produced by the cyanobacterial community, the toxin concentrations and toxin quota. Generalized linear models showed that a Toxin Diversity Index (TDI) increased with latitude, while it decreased with water stability. Increases in TDI were explained through a significant increase in toxin variants such as MC-YR, anatoxin and cylindrospermopsin, accompanied by a decreasing presence of MC-LR. While global warming continues, the direct and indirect effects of increased lake temperatures will drive changes in the distribution of cyanobacterial toxins in Europe, potentially promoting selection of a few highly toxic species or strains
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