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Veröffentlichung Current approaches to cyanotoxin risk assessment and risk management around the globe(2014)Toxic cyanobacteria became more widely recognized as a potential health hazard in the 1990s, and in 1998 the World Health Organization (WHO) first published a provisional Guideline Value of 1 ìg L-1for microcystin-LR in drinking-water. In this publication we compare risk assessment and risk management of toxic cyanobacteria in 17 countries across all five continents. We focus on the three main (oral) exposure vehicles to cyanotoxins: drinking-water, water related recreational and freshwater seafood. Most countries have implemented the provisional WHO Guideline Value, some as legally binding standard, to ensure the distribution of safe drinking-water with respect to microcystins. Regulation, however, also needs to address the possible presence of a wide range of other cyanotoxins and bioactive compounds, for which no guideline values can be derived due to insufficient toxicological data. The presence of microcystins (commonly expressed as microcystin-LR equivalents) may be used as proxy for overall guidance on risk management, but this simplification may miss certain risks, for instance from dissolved fractions of cylindrospermopsin and cyanobacterial neurotoxins. An alternative approach, often taken for risk assessment and management in recreational waters, is to regulate cyanobacterial presence - as cell numbers or biomass - rather than individual toxins. Here, many countries have implemented a two or three tier alert level system with incremental severity. These systems define the levels where responses are switched from Surveillance to Alert and finally to Action Mode and they specify the short-term actions that follow. Surface bloom formation is commonly judged to be a significant risk because of the elevated concentration of microcystins in a scum. Countries have based their derivations of legally binding standards, guideline values, maximally allowed concentrations (or limits named otherwise) on very similar scientific methodology, but underlying assumptions such as bloom duration, average body size and the amount of water consumed while swimming vary according to local circumstances. Furthermore, for toxins with incomplete toxicological data elements of expert judgment become more relevant and this also leads to a larger degree of variation between countries thresholds triggering certain actions. Cyanobacterial blooms and their cyanotoxin content are a highly variable phenomenon, largely depending on local conditions, and likely concentrations can be assessed and managed best if the specific conditions of the locality are known and their impact on bloom occurrence are understood. Risk Management Frameworks, such as for example the Water Safety Plan concept of the WHO and the ´bathing water profile of the European Union are suggested to be effective approaches for preventing human exposure by managing toxic cyanobacteria from catchment to consumer for drinking water and at recreational sites.
© www.sciencedirect.comVeröffentlichung Cyanobacterial blooms. Ecology, prevention, mitigation and control: Editorial to a CYANOCOST Special Issue(2016) Ibelings, Bastiaan W.; Fastner, Jutta; Bormans, Myriam; Visser, Petra M.This is the Editorial to a Special Issue entitled "Cyanobacterial blooms. Ecology, prevention, mitigation and controlŁ. The Special Issue is a product of a European COST Action, CYANOCOST. In this Special Issue, contributions describe methods currently available for the management of cyanobacterial blooms, a key issue threatening the ecological functioning of lakes and the ecosystem services they provide . Contributions start with a section on the prevention of blooms, through the restriction of nutrient availability for cyanobacterial development at three levels: (1) in the catchment, (2) at the inflow to the lake and (3) in-lake methods, including nutrient release from the sediment. Then follows a section on control of blooms where blooms could be formed in the lake, but the chosen treatment restricts cyanobacterial growth to a level where risks and negative effects are minimal, e.g., artificial mixing, flushing or biomanipulation. The Special Issue continues with contributions on mitigation where blooms do develop, but physical and chemical methods mitigate the negative effects. For effective control key traits of the dominant cyanobacteria, characteristics of the lake system and an adequate design of the control method must come together. Each contribution answers questions like: what is the proposed or proven working mechanism of a given method? What have been the successes and failures? What are the reasons for success or failure? How is success linked to characteristics of the waterbody being treated? The Special Issue is concluded with contributions aiming at social and political aspects of bloom management .
Quelle: http://link.springer.comVeröffentlichung CYANOCOST special issue on cyanobacterial blooms: synopsis̶a critical review of the management options for their prevention, control and mitigation(2016) Ibelings, Bastiaan W.; Bormans, Myriam; Fastner, Jutta; Visser, Petra M.Nuisance, toxic cyanobacterial blooms are a persistent and globally expanding problem. Prevention of blooms requires that external and internal sources of nutrients are managed to levels where development of cyanobacterial blooms is restricted. Control of blooms, in which their presence is reduced to a level where they no longer pose a risk through additional measures such as biomanipulation or artificial mixing, demands that three elements come together: (1) understanding of the key ecological traits of the dominant cyanobacteria taxa, (2) system analysis of the lake, in particular its morphometry, water and nutrient balance, (3) adequate design and execution of the management methods of choice. All three elements are important for choosing effective management interventions and predicting their outcome. Mitigation of blooms reduces the risks and harmful effects of blooms if they cannot be prevented or sufficiently controlled, methods such as harvesting of surface scums or application of cyanocides may be used in those cases where water quality improvement is urgent. Ultimately, managing cyanobacterial blooms is most effective in the context of developing a Water Safety Plan. This is a risk assessment and management approach developed by the World Health Organization and provides a platform for bringing together the stakeholders who have a say about activities in the catchment causing eutrophication. Together, they can develop and implement control measures in the chain from catchment to drinking-water offtake which effectively mitigate eutrophication and thus protect humans and the lake ecosystem services they rely on from effects of toxic cyanobacteria.
Quelle: http://link.springer.comVeröffentlichung Eutrophication assessment in the transit area German Bight (North Sea) 2006-2014 - Stagnation and limitations(2018) Brockmann, Uwe; Topcu, Dilek H.; Leujak, Wera; Schütt, M.The eutrophication status of the German Bight (North Sea) has been assessed the third time since 1998 according to the OSPAR-Comprehensive Procedure between 2006 and 2014. Since the 1980s nutrient discharges and atmospheric nitrogen deposition had declined significantly but chlorophyll a and nutrient concentrations remained above assessment levels inshore and in inner coastal waters, reflecting continuing eutrophication. Recently local river discharges stagnated or increased again and total nitrogen remained above a reduction target of 200 myM. Most nutrients and conversion products were imported by a coastal current, passing the German Bight. Organic matter was trapped in offshore bottom waters in the ancient Elbe valley, causing repeated annual oxygen minima (<6 mg/L) and a classification as Problem Area. Effects of national reduction measures are limited in the transit area German Bight because improvements in open coastal waters require international efforts, based on comprehensive analyses. © 2018 Elsevier Ltd. All rights reserved.Veröffentlichung Nutrient criteria for surface waters under the European Water Framework Directive: Current state-of-the-art, challenges and future outlook(2019) Poikane, Sandra; Claussen, Ulrich; Kelly, Martyn G.; Salas Herrero, Fuensanta; Leujak, WeraThe aim of European water policy is to achieve good ecological status in all rivers, lakes, coastal and transitional waters by 2027. Currently, more than half of water bodies are in a degraded condition and nutrient enrichment is one of the main culprits. Therefore, there is a pressing need to establish reliable and comparable nutrient criteria that are consistent with good ecological status. This paper highlights the wide range of nutrient criteria currently in use by Member States of the European Union to support good ecological status and goes on to suggest that inappropriate criteria may be hindering the achievement of good status. Along with a comprehensive overview of nutrient criteria, we provide a critical analysis of the threshold concentrations and approaches by which these are set. We identify four essential issues: (1) Different nutrients (nitrogen and/or phosphorus) are used for different water categories in different countries. (2) The use of different nutrient fractions (total, dissolved inorganic) and statistical summary metrics (e.g., mean, percentiles, seasonal, annual) currently hampers comparability between countries, particularly for rivers, transitional and coastal waters. (3) Wide ranges in nutrient threshold values within shared water body types, in some cases showing more than a 10-fold difference in concentrations. (4) Different approaches used to set threshold nutrient concentrations to define the boundary between "good" and "moderate" ecological status. Expert judgement-based methods resulted in significantly higher (less stringent) good-moderate threshold values compared with data-driven approaches, highlighting the importance of consistent and rigorous approaches to criteria setting. We suggest that further development of nutrient criteria should be based on relationships between ecological status and nutrient concentrations, taking into account the need for comparability between different water categories, water body types within these categories, and countries. © 2019 The Authors. Published by Elsevier B.V.Veröffentlichung Cyanobacteria and cyanotoxins in a changing environment: concepts, controversies, challenges(2021) Chorus, Ingrid; Fastner, Jutta; Welker, MartinConcern is widely being published that the occurrence of toxic cyanobacteria is increasing in consequence of climate change and eutrophication, substantially threatening human health. Here, we review evidence and pertinent publications to explore in which types of waterbodies climate change is likely to exacerbate cyanobacterial blooms; whether controlling blooms and toxin concentrations requires a balanced approach of reducing not only the concentrations of phosphorus (P) but also those of nitrogen (N); how trophic and climatic changes affect health risks caused by toxic cyanobacteria. We propose the following for further discussion: (i) Climate change is likely to promote blooms in some waterbodies - not in those with low concentrations of P or N stringently limiting biomass, and more so in shallow than in stratified waterbodies. Particularly in the latter, it can work both ways - rendering conditions for cyanobacterial proliferation more favourable or less favourable. (ii) While N emissions to the environment need to be reduced for a number of reasons, controlling blooms can definitely be successful by reducing only P, provided concentrations of P can be brought down to levels sufficiently low to stringently limit biomass. Not the N:P ratio, but the absolute concentration of the limiting nutrient determines the maximum possible biomass of phytoplankton and thus of cyanobacteria. The absolute concentrations of N or P show which of the two nutrients is currently limiting biomass. N can be the nutrient of choice to reduce if achieving sufficiently low concentrations has chances of success. (iii) Where trophic and climate change cause longer, stronger and more frequent blooms, they increase risks of exposure, and health risks depend on the amount by which concentrations exceed those of current WHO cyanotoxin guideline values for the respective exposure situation. Where trophic change reduces phytoplankton biomass in the epilimnion, thus increasing transparency, cyanobacterial species composition may shift to those that reside on benthic surfaces or in the metalimnion, changing risks of exposure. We conclude that studying how environmental changes affect the genotype composition of cyanobacterial populations is a relatively new and exciting research field, holding promises for understanding the biological function of the wide range of metabolites found in cyanobacteria, of which only a small fraction is toxic to humans. Overall, management needs case-by-case assessments focusing on the impacts of environmental change on the respective waterbody, rather than generalisations. © 2021 by the authorsVeröffentlichung Eutrophication, contaminants, litter and climate change(2022) Busse, Lilian; Claussen, Ulrich; Krakau, Manuela; Künitzer, Anita; Leujak, Wera; Weiß, Andrea; Werner, StefanieDie Ostsee ist nach wie vor von zahlreichen Belastungen betroffen. Es sind weitere Anstrengungen erforderlich, um diese zu reduzieren und gesunde und widerstandsfähige Meeresökosysteme sowie ihre nachhaltige Nutzung zu erreichen. Dies kann nur durch die Zusammenarbeit der Ostseeanrainerstaaten und eine starke regionale Governance erzielt werden. Der Ostseeaktionsplan ist das vielversprechendste Instrument, diese Bemühungen für die Ostsee umzusetzen und die globalen Ziele des Meeresschutzes voranzubringen. ©2022 Walter de Gruyter GmbH