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Recent advances in molecular biomonitoring open new horizons for aquatic ecosystem assessment. Rapid and cost-effective methods based on organismal DNA or environmental DNA (eDNA) now offer the opportunity to produce inventories of indicator taxa that can subsequently be used to assess biodiversity and ecological quality. However, the integration of these new DNA-based methods into current monitoring practices is not straightforward, and will require coordinated actions in the coming years at national and international levels. To plan and stimulate such an integration, the European network DNAqua-Net (COST Action CA15219) brought together international experts from academia, as well as key environmental biomonitoring stakeholders from different European countries. Together, this transdisciplinary consortium developed a roadmap for implementing DNA-based methods with a focus on inland waters assessed by the EU Water Framework Directive (2000/60/EC). This was done through a series of online workshops held in April 2020, which included fifty participants, followed by extensive synthesis work. The roadmap is organised around six objectives: 1) to highlight the effectiveness and benefits of DNA-based methods, 2) develop an adaptive approach for the implementation of new methods, 3) provide guidelines and standards for best practice, 4) engage stakeholders and ensure effective knowledge transfer, 5) support the environmental biomonitoring sector to achieve the required changes, 6) steer the process and harmonise efforts at the European level. This paper provides an overview of the forum discussions and the common European views that have emerged from them, while reflecting the diversity of situations in different countries. It highlights important actions required for a successful implementation of DNA-based biomonitoring of aquatic ecosystems by 2030.

Mitteilungen / BfG. - 35.2021. - ISSN 1431 - 2409

Cyanobacteria synthesize a large variety of secondary metabolites including toxins. Microcystins (MCs) with hepato- and neurotoxic potential are well studied in bloom-forming planktonic species of temperate and tropical regions. Cyanobacterial biofilms thriving in the polar regions have recently emerged as a rich source for cyanobacterial secondary metabolites including previously undescribed congeners of microcystin. However, detection and detailed identification of these compounds is difficult due to unusual sample matrices and structural congeners produced. We here report a time-efficient liquid chromatography-mass spectrometry (LC-MS) precursor ion screening method that facilitates microcystin detection and identification. We applied this method to detect six different MC congeners in 8 out of 26 microbial mat samples of the Svalbard Archipelago in the Arctic. The congeners, of which [Asp3, ADMAdda5, Dhb7] MC-LR was most abundant, were similar to those reported in other polar habitats. Microcystins were also determined using an Adda-specific enzyme-linked immunosorbent assay (Adda-ELISA). Nostoc sp. was identified as a putative toxin producer using molecular methods that targeted 16S rRNA genes and genes involved in microcystin production. The mcy genes detected showed highest similarities to other Arctic or Antarctic sequences. The LC-MS precursor ion screening method could be useful for microcystin detection in unusual matrices such as benthic biofilms or lichen. published

The global biogeography of microorganisms remains poorly resolved, which limits the current understanding of microbial resilience toward environmental changes. Using high-throughput 16S rRNA gene amplicon sequencing, we characterized the microbial diversity of terrestrial and lacustrine biofilms from the Arctic, Antarctic and temperate regions. Our analyses suggest that bacterial community compositions at the poles are more similar to each other than they are to geographically closer temperate habitats, with 32% of all operational taxonomic units (OTUs) co-occurring in both polar regions. While specific microbial taxa were confined to distinct regions, representing potentially endemic populations, the percentage of cosmopolitan taxa was higher in Arctic (43%) than in Antarctic samples (36%). The overlap in polar microbial OTUs may be explained by natural or anthropogenically-mediated dispersal in combination with environmental filtering. Current and future changing environmental conditions may enhance microbial invasion, establishment of cosmopolitan genotypes and loss of endemic taxa. published

Cyanobacteria (more commonly known as blue-green algae) are photosynthetic bacteria with a worldwide distribution. They are most common in the freshwater environment but are also present in many marine waters. As they are pioneer-organisms and they can often be found in extreme environments. They also constitute the dominant primary producers in the terrestrial Polar Regions and therefore have a pivotal role in polar ecosystems. In freshwater streams, ponds, and lakes that are formed during the polar summer, they occur as benthic or floating mats several millimetres to centimetres thick, sometimes covering several square meters. These mats are the nutritional basis and the micro-habitat for several other types of organisms (primarily proto- and metazoa).This study describes the species diversity of cyanobacterial mat communities from the Arctic and Antarctic that were collected prior to and during the thesis using molecular phylogenetic techniques. The characterization was accomplished by morphological identification as well as the sequencing of the ribosomal RNA genes and the more variable ITS-region (intergenic spacer region). Conventional molecular biological methods (clone-library, automated ribosomal intergenic spacer analysis (ARISA)) were applied as well as „Next-Generation-Sequencing“ based on the 454® technology. The latter allows thousands of sequences to be obtained from a single sample. Using these methods a comprehensive picture of the phylogenetic diversity could be obtained and mats from the Arctic and the Antarctic region compared with and within each other.Cyanobacteria synthesize multiple secondary metabolites, some of which are toxic to most higher organisms including humans. Health hazards or even life threatening incidents regularly occur in the temperate and tropical regions during bloom events (mass-occurrences of cyanobacteria).This study demonstrated that cyanobacterial toxins are present in cyanobacterial mats of the Arctic and the Antarctic. In the Arctic two cyanobacterial toxins were recorded for the first time: An unusual variant of the cyanobacterial hepatotoxin microcystin. This toxin acts as an inhibitor of cellular protein phosphatases (PP 1, 2A, 4 und 5). The second toxin identified was the neurotoxic saxitoxin which inhibits neuronal signal propagation by blocking Na2+ channels. Cylindrospermopsin, a protein synthesis inhibitor was detected for the first time in the Antarctic. These results indicate that the potential for toxin production in the cyanobacterial communities of the Arctic and Antarctic is higher than previously thought.The Polar Regions are currently subject to profound change: Temperatures are increasing at higher rates than anywhere else on the planet. In is expected that a consequence of climate change will be that the composition of the mat communities comprising cyanobacteria and associated proto- and metazoans, are affected. Because of their simple trophic structure and their sensitivity to change, they are an ideal model system for the exploration of climate induced changes. Therefore the effect of climate change on the diversity and toxicity of cyanobacterial mats was studied here in a laboratory based approach. Increased temperatures (8 - 16 °C) resulted in a higher concentration of microcystin as well as in structural changes of the community composition. Based on these results as well as on previous studies, it can be expected that climate change will affect the toxicity of cyanobacteria in the Polar Regions and in lower latitudes. A general increase and a wider distribution of toxic cyanobacteria, as well as an increase of the rate of toxin production may be expected.