Temperature Effects Explain Continental Scale Distribution of Cyanobacterial Toxins

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.Peer reviewe

Phytoplankton response to fish-induced environmental changes in a temperate shallow pond-type lake

Since 1967, the temperate, shallow, pond-type Lake Warniak has been subjected to different biomanipulation methods including the introduction of common carp, Cyprinus carpio L., grass carp, Ctenopharyngodon idella (Val.), silver carp, Hypophthalmichthys molitrix (Val.), and bighead carp, Hypophthalmichthys nobilis (Richardson) and then their removal in an effort to control macrophytes and phytoplankton. Recently, pilot stocking with predatory fish, particularly pike, Esox lucius L., has also been conducted. Hence, an examination of the long-term response patterns of phytoplankton to multiple fish-induced stressors was undertaken. In recent years, Chara domination (2000-2004) has helped to stabilize a clear-water state, high/good ecological status, and meso-eutrophic conditions. After the disappearance of Charales in 2004, the rapid, unstable changes in phytoplankton biomass, structure, and biodiversity suggested a shift toward a turbid-water state. As a result, the phytoplankton assemblages changed from those dominated by cryptophytes Y+X2+X1+LO (2000-2004) through those dominated by cyanobacteria K (2005-2008), dinoflagellates LO+Y (2009-2011), and cryptophytes Y+LO+F+X2 (2012), to those dominated by diatoms D+K+P+A (2013-2014) with representative taxa that occur in nutrient-rich and/or nutrient-poor water bodies. The 1967-2014 changes indicated that four periods, two with clear-water state and two with turbid-water state, alternately, one after the other, resulted from different fish pressure. Higher autochthonous fish biomass was usually accompanied by lower phytoplankton biomass. In contrast, the introduction of Cyprinidae fish had a stimulating effect on summer phytoplankton dominated by cyanobateria. Among the nutrients, only phosphorus played an important role

Legal and remedial actions against the damage to the aquatic environment. A case study of an ecological disaster on the Odra River

The subject of this article are the legal consequences of the ecological disaster that occurred on the Odra River, as well as legal instruments and corrective actions in the field of liquidation of damage in the water environment. In order to improve the effectiveness of the water management and protection system, especially in the event of a natural disaster in water reservoirs, as exemplified by the ecological disaster on the Odra River, changes are required with regard to water law in the field of monitoring, control, information system and duties of competent authorities. It is also necessary to work out appropriate procedures, which will contribute to a faster response in such cases and more effective preventive and corrective actions

Rapid monitoring of cyanobacteria in lakes – a case study in the Wel River catchment, Poland

The purpose of the study was to ascertain the effect of cyanobacterial abundance and its taxonomic structure on the results of measurements made by a fluorometric device designed to detect in situ chlorophyll a and phycocyanin. A multiparameter water quality probe was tested at 10 lakes located in the Wel River catchment. We found a strong correlation between the chlorophyll a concentration determined by laboratory procedure (CHL-a) and that obtained as a result of the probe measurements (YSI CHL-a) (R=0.78) as well as between the YSI CHL-a and the total phytoplankton biomass (R=0.73), whereas YSI CHL-a was not a good predictor of cyanobacterial biomass (R=0.24). The phycocyanin recorded by the probe was proportional to the total biomass of cyanobacteria (R=0.86); however, this cyanobacterial taxonomic structure influenced the fluorometric signal. Nevertheless, our study showed significant differentiation of phycocyanin measurement distribution at different levels of cyanobacterial abundance (10 mg L−1), which indicates that the PC-YSI measurements are valuable in the detection of increased risk of exceeding health alert thresholds recommended by the WHO

The isotherm and kinetic studies of the biosorption of heavy metals by non-living cells of Chlorella vulgaris

In general, the biosorption of heavy metals by various types of non-living organisms appears to be a very effective, low-cost and innovative method for their removal from aquatic environments. The aim of this study was to determine the applicability of adsorption isotherms and kinetic models during the biosorbent activity of non-living Chlorella to the removal of Cd, Cu and Pb. Dead cells of Chlorella vulgaris were used to remove these heavy metals from aqueous solution in experimental conditions, i.e. under various condition of pH, biosorbent dosage and contact time. Afterwards, the Langmuir and Freundlich adsorption isotherm models and the sorption kinetic (pseudo-first and pseudo-second order models, and intraparticle diffusion) were applied to the experimental data to check the effectiveness of the removal process. The removal of heavy metals on C. vulgaris following the order of Pb+2 > Cu+2 > Cd+2 was confirmed by the maximum biosorption capacities (qmax), the Langmuir constant (b), separation factor (RL) and Freundlich intensity parameter (1/n) values. The equilibrium data were well fitted with the Langmuir and Freundlich isotherm models. The adsorption process followed the pseudo-second-order model and it suggested that such kinetics is the most effective. The present results confirmed highly efficient biosorbent activity of C. vulgaris in the removal of heavy metals, especially Cd, Cu and Pb, from aqueous solution. The environmentally friendly origin indicates that non-living cells of C. vulgaris could find many broad-scale, cost-effective and alternative applications

The isotherm and kinetic studies of the biosorption of heavy metals by non-living cells of Chlorella vulgaris

In general, the biosorption of heavy metals by various types of non-living organisms appears to be a very effective, low-cost and innovative method for their removal from aquatic environments. The aim of this study was to determine the applicability of adsorption isotherms and kinetic models during the biosorbent activity of non-living Chlorella to the removal of Cd, Cu and Pb. Dead cells of Chlorella vulgaris were used to remove these heavy metals from aqueous solution in experimental conditions, i.e. under various condition of pH, biosorbent dosage and contact time. Afterwards, the Langmuir and Freundlich adsorption isotherm models and the sorption kinetic (pseudo-first and pseudo-second order models, and intraparticle diffusion) were applied to the experimental data to check the effectiveness of the removal process. The removal of heavy metals on C. vulgaris following the order of Pb+2 > Cu+2 > Cd+2 was confirmed by the maximum biosorption capacities (qmax), the Langmuir constant (b), separation factor (RL) and Freundlich intensity parameter (1/n) values. The equilibrium data were well fitted with the Langmuir and Freundlich isotherm models. The adsorption process followed the pseudo-second-order model and it suggested that such kinetics is the most effective. The present results confirmed highly efficient biosorbent activity of C. vulgaris in the removal of heavy metals, especially Cd, Cu and Pb, from aqueous solution. The environmentally friendly origin indicates that non-living cells of C. vulgaris could find many broad-scale, cost-effective and alternative applications

Harmful blooms across a longitudinal gradient in central Europe during heatwave: Cyanobacteria biomass, cyanotoxins, and nutrients

Climate change has increased the frequency, duration and intensity of heatwaves in Europe. These extreme events result in alterations of physical, chemical, and biological properties of lakes that may synergistically promote cyanobacterial dominance. In our study we focused on cyanobacterial blooms in lakes distributed over a longitudinal gradient in Central Europe during one of the “top ten European heat waves” in summer 2015. 92 lakes were included in the study, located across three climatic subregions: cool northern lakes, situated in Lithuania, temperate northern lakes in Poland, and warm northern lakes in Croatia. The objective of the study was to determine if cyanobacterial biomass, predominant species, and cyanotoxin concentration differed, across the south-north gradient, as a function of water temperature, total phosphorus, and total nitrogen. Statistical significance of observed patterns was tested using the Kruskal-Wallis rank sum test and the generalized linear model. We found the lowest average epilimnion temperature, but the highest average cyanobacterial biomass in the northern, ‘cool’ lakes while the highest average temperature with the lowest average cyanobacterial biomass in the southern, ‘warm’ lakes. The concentration of cyanotoxins was also the highest in the ‘cool’ lakes. Total phosphorus and total nitrogen correlated significantly with cyanobacterial biomass, cyanotoxins concentration and biomass of some cyanobacterial species (mainly Planktothrix agardhii), regardless of the latitude. Only in the ‘cool’ lakes concentration of cyanotoxins (microcystins and anatoxin-a) correlated significantly with cyanobacterial biomass and the biomass of some dominant cyanobacterial species (P. agardhii). Our results emphasized the differences of heat weaves impact on lakes of various latitudes, with the strongest increase in toxic cyanobacterial blooms in northern ‘cool’ lakes, situated in high latitudes. On the other hand, nutrients directly enhanced blooms across all the studied latitudes of Central Europe. The cyanobacteria species dominating in blooms might be recognized as ecological indicators of climate change, especially in the north-eastern part of Europe

Stratification strength and light climate explain variation in chlorophyll a at the continental scale in a European multilake survey in a heatwave summer

To determine the drivers of phytoplankton biomass, we collected standardized morphometric, physical, and biological data in 230 lakes across the Mediterranean, Continental, and Boreal climatic zones of the European continent. Multilinear regression models tested on this snapshot of mostly eutrophic lakes (median total phosphorus [TP] = 0.06 and total nitrogen [TN] = 0.7 mg L-1), and its subsets (2 depth types and 3 climatic zones), show that light climate and stratification strength were the most significant explanatory variables for chlorophyll a (Chl a) variance. TN was a significant predictor for phytoplankton biomass for shallow and continental lakes, while TP never appeared as an explanatory variable, suggesting that under high TP, light, which partially controls stratification strength, becomes limiting for phytoplankton development. Mediterranean lakes were the warmest yet most weakly stratified and had significantly less Chl a than Boreal lakes, where the temperature anomaly from the long-term average, during a summer heatwave was the highest (+4 degrees C) and showed a significant, exponential relationship with stratification strength. This European survey represents a summer snapshot of phytoplankton biomass and its drivers, and lends support that light and stratification metrics, which are both affected by climate change, are better predictors for phytoplankton biomass in nutrient-rich lakes than nutrient concentrations and surface temperature.Peer reviewe