Nitrogen fixation by cyanobacteria stimulates production in Baltic food webs

Filamentous, nitrogen-fixing cyanobacteria form extensive summer blooms in the Baltic Sea. Their ability to fix dissolved N₂ allows cyanobacteria to circumvent the general summer nitrogen limitation, while also generating a supply of novel bioavailable nitrogen for the food web. However, the fate of the nitrogen fixed by cyanobacteria remains unresolved, as does its importance for secondary production in the Baltic Sea. Here, we synthesize recent experimental and field studies providing strong empirical evidence that cyanobacterial nitrogen is efficiently assimilated and transferred in Baltic food webs via two major pathways: directly by grazing on fresh or decaying cyanobacteria and indirectly through the uptake by other phytoplankton and microbes of bioavailable nitrogen exuded from cyanobacterial cells. This information is an essential step toward guiding nutrient management to minimize noxious blooms without overly reducing secondary production, and ultimately most probably fish production in the Baltic Sea.     

Baltic Sea ecosystem-based management under climate change: Synthesis and future challenges

Ecosystem-based management (EBM) has emerged as the generally agreed strategy for managing ecosystems, with humans as integral parts of the managed system. Human activities have substantial effects on marine ecosystems, through overfishing, eutrophication, toxic pollution, habitat destruction, and climate change. It is important to advance the scientific knowledge of the cumulative, integrative, and interacting effects of these diverse activities, to support effective implementation of EBM. Based on contributions to this special issue of AMBIO, we synthesize the scientific findings into four components: pollution and legal frameworks, ecosystem processes, scale-dependent effects, and innovative tools and methods. We conclude with challenges for the future, and identify the next steps needed for successful implementation of EBM in general and specifically for the Baltic Sea.     

A contingency model of decision-making involving risk of accidental loss

Decision-making involving risk of accidental loss occurs in a variety of settings. The constraints of the decision settings have a strong impact on decision-making. Different decision settings may thus call for different approaches to decision support. The purpose of this paper is to propose a contingency model of decision-making involving risk of accidental loss. Based on two dimensions, (a) proximity to hazard and (b) level of authority, I identify five types of decision settings: (1) operations, (2) business management, (3) administrative and technical support functions, (4) political arenas, and (5) crisis handling. Each setting is characterised in terms of dominant constraints, dominant decision criteria, and representative decision modes.Decision-making is constrained and influenced by previous decisions, and decisions may interact in the way they influence the risk of accidental loss. The following set of concepts may help us identify ways in which safety may be affected by interactions between decisions: (1) distributed decision-making and local optimization, (2) meta-decisions, (3) absorption of uncertainty, and (4) normalization of deviance.Advice for improving decision-making can be derived from the proposed model by identifying possible problems related to each type of decision setting and each pattern of interaction between decisions. The possible problems may be used as a basis for identifying relevant functions of decision aids and to propose specific decision aids. A similar analysis may be performed with regard to the ways in which decisions may interact in their impact on safety.     

New Evidence for the presence of arsenocholine in shrimps (Pandalus borealis) by use of pyrolysis gas chromatography — atomic absorption spectrometry/mass spectrometry

An analytical method for the structure elucidation of quarternary organoarsenic compounds in trace amounts in fish and crustaceans has been developed in this laboratory. The two major organoarsenicals found in shrimps have been separated by ion-exchange chromatography and their stucture has been studied by the use of pyrolysis gas chromatography. Their degradation in the pyrolyzer unit has been studied by the use of atomic absorption spectrophotometer or mass spectrometer as detectors. A comparison of the analytical data of these substances and data from synthetic reference substances show complete agreement. The structures of reference compounds have been confirmed by use of nuclear magnetic resonance spectrometry and fast atom bombardment (FAB) mass spectrometry. It is demonstrated that both of the organoarsenic compounds in shrimps have a trimethylarsonio moiety e.g. the compounds have a quarternary structure. Furthermore, the more basic organoarsenic compound has a mass spectrometric fragmentation pattern similar to synthetic arsenocholine and acetylarsenocholine. Treatment of arsenobetaine with hot base produces trimethylarsineoxide in a high yield (96%). Arsenocholine, however, remains unchanged during this treatment. Treatment with sodium benzenethiolate does not result in chemical demethylation, which shows that this method together with gas chromatography-mass spectrometry is not feasible for confirmation of its structure.     

有关人类影响波罗的海生态系的认识:近数十年来有关观点的转变

20世纪60年代后期,已发现波罗的海出现了严重的环境问题,其中包括因有机氯和重金属而导致的生物区系污染,以及日益严重的深水缺氧等.开始把有毒污染物--包括新发现的多氯联苯(PCB)--看作是对波罗的海生态系统的主要威胁,在波罗的海海豹和白尾海雕中发现的生殖受损问题,则意味着也威胁到了人类的食用鱼类.各种应对措施逐渐产生了结果,当今对限制波罗的海毒物污染的斗争已成为国际环境方面的成功实例.计算表明,波罗的海深水耗氧量肯定已有增加,波罗的海营养盐负荷也已有增加,其中氯约为4倍、磷约为8倍.已逐渐积累了生态系统各营养层日益增加的有机生产量证据.首先认为磷限制着波罗的海的初级生产力,但测量很快表明,在开阔的波罗的海本体,除了蓝藻外,真正的普遍限制因素则是氮.今天有关的争论是,磷是否通过限制固氮者而控制了开阔海域生态系统生产力,即使在那里浮游植物明显地受着氮的限制.波罗的海的教训告诉我们,我们新发现的环境问题经历着反复变化,而且科学家可能要花费数十年的时间才能就其成因达成共识.当社会决定采取应对措施时,可能需要几十年时间,这些措施才会产生效果,对自然界来说,则需几十年时间才能得以恢复.由此可见,环境管理决策很难等待科学上的定论.因此,我们应该把环境管理决策视为这样一种经验,它需要被监测、被总结,必要时要加以修改.     

Über formbildende Wirkstoffe bei Azotobakter chroococcum und der Einfluß dieser formativen Wirkstoffe auf die Bildung von Gigasformen bei Bacterium radicicola

The Science of Nature -     

Classifying the cases

This paper provides a classification and discussion of the empirical cases presented in this special issue. The cases are classified according to the dimensions “proximity to hazard” and “level of authority”. The majority of cases concern decision-making at the blunt end, i.e. removed in space and causal distance from the sources of hazard. The papers show that many decision processes at the blunt end are characterized by various forms of bounded rationality, but there is one notable exception. Normative evaluations of the goodness of the observed decisions processes are absent in several papers. This suggests that there may be a need to clarify the normative basis for research-based advice on decision-making.     

Bioassay-directed identification of toxic organic compounds in creosote-contaminated groundwater

Despite the fact that creosote mainly consists of polycyclic aromatic hydrocarbons (PAHs), more polar compounds like phenolics, benzenes and N-, S-, O-heterocyclics dominate the groundwater downstream from creosote-contaminated sites. In this study, bioassay-directed fractionation, combined with fullscan GC-MS, identified organic toxicants in creosote-contaminated groundwater. An organic extract of creosote-contaminated groundwater was fractionated on a polar silica column using high performance liquid chromatography (HPLC), and the toxicity of the fractions was measured by the Microtox-bioassay. PAHs, which comprise up to 85% of pure creosote, accounted for only about 13% of total toxicity in the creosote-contaminated groundwater, while methylated benzenes, phenolics and N-heterocyclics accounted for ca. 80% of the measured toxicity. The fraction containing alkylated quinolines was the most toxic single fraction, accounting for 26% of the total measured toxicity. The results imply that focus on PAHs may underestimate risks associated with creosote-contaminated groundwater, and that environmental risk assessment should focus to a higher degree on substituted PAHs and phenolics because they are more toxic than the unsubstituted ones. Additionally, benzenes and N-heterocyclics (e.g., alkylated quinolines) should be assessed.     

The usage of safety management tools in Swedish municipalities

Although municipalities clearly deal with a broad range of safety issues, little is known about their safety management practices and their usage of safety management tools across sectors. In order to open up the municipal safety management toolbox, this study explores which tools that are being used in Swedish municipalities and by which municipal sector. Our results indicate that tools such as risk inventory, safety rounds and risk analysis are broadly used across most sectors, while usage of other tools is more restricted to certain sectors. Legislative requirements, tool characteristics and actual needs are assumed to influence the usage of tools. Further research in this field is needed for better adaption of safety management tools to municipal needs.