Abstract from a recent paper by Lurling et al., published in Frontiers in Microbiology.
“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-a, while algal chlorophyll-a concentrations were on average 8% higher at 25°C than at 20°C. A nutrient pulse had a much stronger effect on chlorophyll-a concentrations than warming. Cyanobacterial chlorophyll-a 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-a concentrations were 6 times higher. The results of this study confirm that warming alone yields marginally higher cyanobacteria chlorophyll-a 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.”
Lürling Miquel, Mello Mariana Mendes e, van Oosterhout Frank, de Senerpont Domis Lisette, Marinho Marcelo M. (2018). Response of Natural Cyanobacteria and Algae Assemblages to a Nutrient Pulse and Elevated Temperature. Frontiers in Microbiology 9, 1851. https://www.frontiersin.org/article/10.3389/fmicb.2018.01851
A brief summary about the role of climate change on algae blooms written for the general public, is published by Climate Central.
“Algae occur naturally in most bodies of freshwater and saltwater. It’s normally fairly harmless, but the right combination of warm water, high nutrient levels, and adequate sunlight combined can cause a harmful algae bloom. These blooms can damage aquatic ecosystems by blocking sunlight and depleting oxygen that other organisms need to survive. Some algae, like red algae and blue-green algae, can produce toxins that damage the human nervous system and the liver (and they also stink — literally)………..”
Read the report here.
The summer 2018 edition of CYANonews is now available. It features new research, tools and related info, forthcoming events, job and research positions.
You can download it here.
Best wishes from CYANOCOST, for summer holidays in clear waters !
Abstract from a recent paper by E. Mantzouki & B. Ibelings, published in Limnology & Oceanography Bulletin (ASLO):
On‐going global warming and eutrophication are expected to promote cyanobacterial dominance worldwide. Although increased lake temperature and nutrients are well‐established drivers of blooms, the mechanisms that determine cyanobacterial biomass are complex, with potentially direct, indirect, and interactive effects. Cyanobacteria can produce toxins that constitute a considerable risk for animal and human health and thus a substantial economic cost if we are to ensure safe drinking water. Such global range phenomena should be studied at a wide spatial scale, to directly compare phytoplankton response in different lake types across contrasting climatic zones. The European Multi Lake Survey (EMLS) sought to harness the power of group science in order to sample lakes across Europe and disentangle the effect of environmental stressors on potentially toxic cyanobacterial blooms. The first EMLS results showed that the distribution of cyanobacterial toxins and the toxic potential in lakes will be highly dependent on direct and indirect effects of temperature. If nutrients are not regulated, then they may interact synergistically with increased lake temperatures to promote cyanobacterial growth more than that of other phytoplankton taxa. Providing continental scale evidence is highly significant for the development of robust models that could predict cyanobacterial or algal response to environmental change.
Mantzouki, E. and Ibelings, B. W. (2018), The Principle and Value of the European Multi Lake Survey. Limnology and Oceanography Bulletin. . doi:10.1002/lob.10259
U.S. EPA Office of Ground Water and Drinking water recently released a video that provides an overview of available tools to support proactive planning for cyanotoxin management in drinking water; watch the video here.
Many thanks to Dr. Lesley D’Anglada, US EPA, Editor of the Freshwater HABs Newsletter for sharing this information.
Abstract of a new paper by Major et al., published in Environmental Science and Pollution Research:
“The composition and abundance of cyanobacteria and their toxins, microcystins (MCs), and cylindrospermopsins (CYN) were investigated using samples collected at monthly intervals from the Amudde side of Koka Reservoir from May 2013 to April 2014. Cyanobacteria were the most abundant and persistent phytoplankton taxa with Microcystis and Cylindrospermopsis species alternately dominating the phytoplankton community of the reservoir and accounting for up to 84.3 and 11.9% of total cyanobacterial abundance, respectively. Analyses of cyanotoxins in filtered samples by HPLC-DAD and LC-MS/MS identified and quantified five variants of MCs (MC-LR, MC-YR, MC-RR, MC-dmLR, and MC-LA) in all samples, with their total concentrations ranging from 1.86 to 28.3 μg L−1 and from 1.71 to 33 μg L−1, respectively. Despite the presence and occasional abundance of Cylindrospermopsis sp., cylindrospermopsin was not detected. Redundancy analysis (RDA) showed that the environmental variables explained 82.7% of the total variance in cyanobacterial abundance and microcystin concentration. The presence of considerably high levels of MCs almost throughout the year represents a serious threat to public health and life of domestic and wild animals”.
Environ Sci Pollut Res https://doi.org/10.1007/s11356-018-2727-2
Abstract of a paper from a collaboration within CYANCOST (Armenia, USA, Greece), that was authored by Minasyan et al. and published in Toxicon:
“This paper presents the first report of cyanobacteria and cyanotoxins from the South Caucasus region, in particular from Lake Yerevan (Armenia). Microcystis, Dolichospermum and Planktothrix were the key genera identified during the growing season. A trend of a remarkable increase in cyanobacterial densities was observed from 2012 to 2013 exhibiting bloom formation in June (by Nostoc linckia) with the highest values in June and August 2013, reaching up to 695.9*103 cells mL−1. Seasonal dependence of cyanobacterial density on temperature, and temperature as a driver for cyanobacterial cells growth and development were suggested. Biogenic nutrients were identified as co-drivers determining species richness and dominance, as well as the distribution of phytoplankton in different parts of the reservoir.
Cyanotoxin concentrations in the filtered biomass were reported during July 2012 for both stations of the reservoir (left and right bank). Microcystin-RR (MC-RR) was the most abundant and the most frequently observed cyanotoxin. Lower MC-LR concentrations were identified in all samples from both stations, with the highest values observed at the right bank in July 2012. [D-Asp3]MC-RR, MC-YR, MC-HtyR, [D-Asp3]MC-LR, MC-HilR, MC-WR, MC-LY and MC-LW were also identified in trace levels. Anatoxin-a (ANA) was reported in the samples from both stations during August 2012. Cylindrospermopsin (CYN) was present in trace concentrations in samples from both stations during July and in the sample from the left bank during September.”
This paper acknowledges CYANOCOST.
Arevik Minasyan, Christophoros Christophoridis, Alan E. Wilson, Sevasti-Kiriaki Zervou, Triantafyllos Kaloudis, Anastasia Hiskia (2018). Diversity of cyanobacteria and the presence of cyanotoxins in the epilimnion of Lake Yerevan (Armenia). Toxicon 150, 28-38.
From the abstract of a paper by Simiyu et al., published in Toxins:
The human health risks posed by exposure to cyanobacterial toxins such as microcystin (MC) through water and fish consumption remain poorly described. During the last two decades, coastal regions of Lake Victoria such as Nyanza Gulf (Kisumu Bay) have shown severe signs of eutrophication with blooms formed by Microcystis producing MC. In this study, the spatial variability in MC concentration in Kisumu Bay was investigated which was mostly caused by Microcystis buoyancy and wind drifting. Small fish (<6 cm) mainly composed of Rastrineobola argentea were examined for MC content by means of biological methods such as ELISA and protein phosphatase inhibition assay (PPIA) and partly by chemical-analytical methods such as LC-MS/MS. Overall, the MC content in small fish was related to the MC content observed in the seston. When comparing the MC content in the seston in relation to dry weight with the MC content in small fish the latter was found three orders of magnitude decreased. On average, the ELISA-determined MC contents exceeded the PPIA-determined MC contents by a factor of 8.2 ± 0.5 (SE) while the MC contents as determined by LC-MS/MS were close to the detection limit. Using PPIA, the MC content varied from 25–109 (mean 62 ± 7) ng/g fish dry weight in Kisumu Bay vs. 14 ± 0.8 ng MC/g in the more open water of L. Victoria at Rusinga channel. Drying the fish under the sun showed little effect on MC content, although increased humidity might indirectly favor photocatalyzed MC degradation.
Benard Mucholwa Simiyu, Steve Omondi Oduor, Thomas Rohrlack , Lewis Sitoki and Rainer Kurmayer (2018).Microcystin Content in Phytoplankton and in Small Fish from Eutrophic Nyanza Gulf, Lake Victoria, Kenya. Toxins 10(7), 275. doi:10.3390/toxins10070275
A review on “Cyanobacterial Blooms” by top-experts in the field has recently been published in Nature Reviews Microbiology (June 2018). The review presents evidence indicating that cyanobacterial blooms are increasing in frequency, magnitude and duration globally. It discusses the traits involved in cyanobacteria dominance and bloom development, environmental drivers, production and modes of action of cyanotoxins and strategies for bloom prevention and control. There is also a special section about historical observations of algal blooms.
The review has references to 188 published articles, with annotations to key publications. This is a must-read for both beginners and experienced scientists in the field.
Jef Huisman, Geoffrey A. Codd, Hans W. Paerl, Bas W. Ibelings, Jolanda M.H. Verspagen and Petra Visser (2018). Cyanobacterial Blooms. Nature Reviews Microbiology. https://doi.org/10.1038/s41579-018-0040-1
Article by Evanthia Mantzouki and Bas Ibelings, Univ. of Geneva.
The first product of the European Multi Lake Survey (EMLS) is published in Toxins. This paper would not have been possible without the EMLS, the grassroots initiative that brought together around 200 scientists from 26 European countries to sample their lakes and answer questions of ecological importance. Understanding global scale phenomena, such as climate warming, requires information of high spatial resolution to investigate if lakes of similar characteristics (e.g. morphometry, trophic status) would respond in a consistent manner to similar environmental forcing. Cyanobacterial occurrence as a typical consequence of environmental perturbation in aquatic systems worldwide, was the centre of attention in the EMLS. Starting from a common goal to produce adequate evidence and eventually push for stricter regulation towards improved freshwater quality, the EMLS consortium (Figure 1) designed straightforward sampling protocols to accommodate the capacity in funding, time, personnel and equipment of all participants, without compromising quality. Cyanotoxins, phytoplankton pigments and environmental parameters were sampled and analysed in a fully standardised way to ensure scientific validity.
As a result of this effort, the first peer-reviewed EMLS article casts light on cyanotoxins and toxin quota distribution across the European continent. In an unexpected -but welcoming for our research purpose!- hot summer in 2015, temperature effects, both directly through boosting physiological processes of cyanobacterial growth and, indirectly through enhancing water stability that facilitate buoyant cyanobacterial cells, determined the spatial distribution of hepatotoxins (microcystins), neurotoxins (anatoxin-a) and cytotoxins cylindrospermopsin). The Northern European lakes were struck by a prolonged heat wave, more than the Mediterranean ones, during the sampling period that pinpointed the reality of climate warming. In such an event, toxin diversity increased along the latitudinal gradient, showing that cyanobacterial toxin production is enhanced not necessarily when it is hot (Mediterranean) but when it gets warmer than usual (heat event in North). Increases in toxin diversity (increase in toxin numbers but also representation of each toxin), entailed an increased presence of cylindrospermopsin, anatoxin and less studied microcystin variants, with a simultaneous decrease in the famous 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.
Reference (Open access):
Mantzouki et al. (2018). Temperature Effects Explain Continental Scale Distribution of Cyanobacterial Toxins. Toxins 2018, 10(4), 156; https://doi.org/10.3390/toxins10040156
EMLS was supported by COST Actions NETLAKE and CYANOCOST.