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.

The goal of this study was a harmonization of diatom identification and counting among diatomists from the Scandinavian and Baltic countries to improve the comparison of diatom studies in this geographical area. An analysis of the results of 25 diatomists following the European standard EN 14407 during an intercalibration exercise showed that a high similarity was achieved by harmonization and not because of a long experience with diatoms. Sources of error were wrong calibration scales, overlooking of small taxa, especially small Navicula s.l., misidentifications (Eunotia rhomboidea was mistaken for Eunotia incisa) and unclear separation between certain taxa in the identification literature. The latter was discussed during a workshop with focus on the Achnanthes minutis-M. Kahlert (*) : sima group, the separation of Fragilaria capucina var. gracilis from F. capucina var. rumpens, and Nitzschia palea var. palea from N. palea var. debilis. The exercise showed also that the Swedish standard diatom method tested here worked fine with acceptable error for the indices IPS (Indice de Polluo-sensibilité Spécifique) and ACID (ACidity Index for Diatoms) when diatomists with a low similarity (Bray-Curtis <60%) with the auditor in at least one of the samples are excluded.

IntroductionAlgal cell walls separate the inside cell content from the environment to protect the cell against desiccation, pathogens, and predators while still allowing exchange of compounds. Toward application of algae biomass as a sustainable resource, disruption of this cell wall (¼cell disruption) is an essential pretreatment step to maximize product recovery in downstream processes of the algae biorefinery. Also for direct use of algae in feed or food, cell rupture is required to increase the bioavailability of algae constituents. Depending on the cell wall structure, the size, and the shape of algae, cell disruption can be challenging. A variety of cell disruption methods is currently available, and new approaches are being elaborated in parallel. Since downstream processing is responsible for a large part of the operational costs in the whole production chain, cell disruption technologies should be low cost and energy efficient and result preferably in high product quality. This chapter provides information on cell wall types and gives an overview of physical-mechanical and (bio-)chemical cell disruption technologies with attention to development stage, energy efficiency, product quality, costs, emerging approaches, and applicability on large scale. Cell wall types in various groups of microalgae and cyanobacteriaThe cell wall composition and architecture of algae and cyanobacteria are highly variable ranging from tiny membranes to multilayered complex structures. Despite the importance of algal cell wall properties in biotechnology, little structural information is available for most species (Scholz et al., 2014). Based on the complexity of surface structures, four cell types could be distinguished (Barsanti and Gualtieri, 2006;Lee, 2008) (Fig. 6.1). A simple cell membrane (Fig. 6.1, Type 1) is present in short-lived stages (e.g., gametes), chrysophytes, raphidophytes, green algae Dunaliella, and haptophytes Isochrysis. It consists of a lipid bilayer with integrated and peripheral proteins. Sometimes a cap of glycolipids and glycoproteins envelops the outer surface of cell membrane. Cell membranes with additional extracellular material are known in cyanobacteria and many groups of algae, including palmelloid phases. It is the most diverse cell wall type that includes various membrane-associated structures (cell wall, Microalgae-Based Biofuels and Bioproducts. http://dx

Inland waters are an important habitat for flora and fauna and are also used for aesthetic, recreational, and industrial needs; therefore, monitoring the current state of freshwaters and applying measures to improve water quality are of high importance. To have an efficient monitoring system that could cover large areas, the use of remote sensing data is crucial. In this study the suitability of the Sentinel-2 Multispectral Imager data is tested for observing cyanobacteria bloom events in the eutrophic lakes and retrieving the chlorophyll-a concentration – an indicator of phytoplankton biomass. The analysis is carried out using data from four lakes in Lithuania – two eutrophic blooming lakes and two oligo-mesotrophic non-blooming lakes. The results showed that reflectances are higher in the eutrophic lakes than in the oligo-mesotrophic lakes due to the presence of an optically active constituent, namely, chlorophyll-a pigment. We tested empirical equations for chlorophyll-a concentration retrieval in eutrophic lakes derived in other studies to check whether they could be used without adaptation to local conditions. Most of the equations performed well (R2 = 0.5–0.8); however, they had high RMSEs = 17–53 μg L–1. The equation used with the bottom of atmosphere data CHL8_L2A (R2 = 0.76) had the lowest RMSE = 9 μg L–1. In addition, we derived empirical equations for eutrophic lakes in Lithuania. The equations that were based on the Sentinel-2 band ratio B5/B4 and the three band (B4, B5, and B8A) expression performed the best (R2 = 0.77–0.79) and had lower RMSE = 7 μg L–1 than empirical equations from other studies. A larger in situ dataset could improve the algorithm performance in retrieving the chlorophyll-a concentration. The first attempts to map water quality parameters in eutrophic lakes in Lithuania using the data received from the Sentinel-2 MSI sensor show good results, as the changes in reflectance, caused by the changes in chlorophyll-a concentration, can be seen from satellite images.

Mechanisms behind expansion of an invasive cyanobacterium Cylindrospermopsis raciborskii have not been fully resolved, and different hypotheses, such as global warming, are suggested. In the East-Central Europe, it is widely occurring in western part of Poland but only in single locations in the East due to some limiting factors. Therefore, broad-scale phytoplankton survey including 117 randomly selected lakes in Poland and Lithuania was conducted. The results showed that C. raciborskii occurred widely in western part of Poland but was absent from other regions and Lithuania except one lake. The regions in which C. raciborskii was present had higher annual mean air temperature, higher maximum air temperature of the warmest month and higher minimum temperature of the coldest month, demonstrating that average air temperature, and indirectly, the duration of growing season might be more important factor driving C. raciborskii distribution than measured in situ water temperature. In turn, the presence of C. raciborskii in single localities may be more related to physiological adaptations of separated ecotype. Collectively, these results provide novel evidence on the influence of temperature on C. raciborskii distribution in East-European regions but also indicate high ecological plasticity of this species.