Release of dissolved organic carbon (DOC) by the scyphozoan jellyfish Aurelia aurita and its potential influence on the production of planktic bacteria

A series of incubation experiments were made to measure the rate of release of dissolved organic carbon (DOC) by the jellyfish Aurelia aurita (L.) (collected in 1991–1992 in Gullmarsfjorden, Sweden). Release of DOC by medusae (9.5 to 18 cm in diameter) from the Skagerrak ranged from 0.70 to 1.6 mg C ind^-1 d^-1 with a mean of 1.2 mg C ind^-1 d^-1 (SD=0.29 mg C ind^-1 d^-1, n=10). Based on data from the literature for two medusa populations, this can be equivalent to 2.5 and 7.1% of the carbon assimilated in one season (June to September). This was similar to the amount of carbon allocated to reproduction. Bacterial abundance was monitored to evaluate the possible stimulating effect of the DOC released. Bacterial growth was stimulated by the presence of A. aurita. The importance of A. aurita as a source of DOC on a large scale is small compared to exudate from primary producers. The volume surrounding each medusa, wherein the DOC released may be enough to sustain a bacterial production such as the one reported from the Swedish west coast, is equivalent to a sphere with a diameter of 0.5 m. Thus, considering the patchy distribution of medusae, the local influence of their DOC release could be important.     

The Rossby Centre Regional Atmospheric Climate Model part I: model climatology and performance for the present climate over Europe

The Rossby Centre Atmospheric Regional Climate Model (RCA2) is described and simulation results, for the present climate over Europe, are evaluated against available observations. Systematic biases in the models mean climate and climate variability are documented and key parameterization weaknesses identified. The quality of near-surface parameters is investigated in some detail, particularly temperature, precipitation, the surface energy budget and cloud cover. The model simulates the recent, observed climate and variability with a high degree of realism. Compensating errors in the components of the surface radiation budget are highlighted and the fundamental causes of these biases are traced to the relevant aspects of the cloud, precipitation and radiation parameterizations. The model has a tendency to precipitate too frequently at small rates, this has a direct impact on the simulation of cloud-radiation interaction and surface temperatures. Great care must be taken in the use of observations to evaluate high resolution RCMs, when they are forced by analyzed boundary conditions. This is particularly true with respect to precipitation and cloudiness, where observational uncertainty is often larger than the RCM bias.     

Comparative health impact assessment of local and regional particulate air pollutants in Scandinavia

The ongoing program Clean Air for Europe (CAFE) is an initiative from the EU Commission to establish a coordinated effort to reach better air quality in the EU. The focus is on particulate matter as it has been shown to have large impact on human health. CAFE requested that WHO make a review of the latest findings on air pollutants and health to facilitate assessments of the different air pollutants and their health effects. The WHO review project on health aspects of air pollution in Europe confirmed that exposure to particulate matter (PM), despite the lower levels we face today, still poses a significant risk to human health. Using the recommended uniform risk coefficients for health impact assessment of PM, regardless of sources, premature mortality related to long-range transported anthropogenic particles has been estimated to be about 3500 deaths per year for the Swedish population, corresponding to a reduction in life expectancy of up to about seven months. The influence of local sources is more difficult to estimate due to large uncertainties when linking available risk coefficients to exposure data, but the estimates indicate about 1800 deaths brought forward each year with a life expectancy reduction of about 2-3 months. However, some sectors of the population are exposed to quite high locally induced concentrations and are likely to suffer excessive reductions in life expectancy. Since the literature increasingly supports assumptions that combustion related particles are associated with higher relative risks, further studies may shift the focus for abatement strategies. CAFE sets out to establish a general cost effective abatement strategy for atmospheric particles. Our results, based on studies of background exposure, show that long-range transported sulfate rich particles dominate the health effects of PM in Sweden. The same results would be found for the whole of Scandinavia and many countries influenced by transboundary air pollution. However, several health studies, including epidemiological studies with a finer spatial resolution, indicate that engine exhaust particles are more damaging to health than other particles. These contradictory findings must be understood and source specific risk estimates have to be established by expert bodies, otherwise it will not be possible to find the most cost effective abatement strategy for Europe. We are not happy with today's situation where every strategy to reduce PM concentrations is estimated to have the same impact per unit change in the mass concentration. Obviously there is a striking need to introduce more specific exposure variables and a higher geographical resolution in epidemiology as well as in health impact assessments.     

罗斯比中心区域气候模型Ⅰ:对当前欧洲气候的气候学及性能模拟

描述了罗斯比中心区域气候模型(RCA2)并依据观测评估了其对整个欧洲当前气候的模拟结果.指出了模型平均气候和气候变率中的系统偏差,确定了关键参数化的缺欠.对一些近地面参数,尤其是温度、降水、地表能量收支和云量进行了较为详细的研究.模型模拟的最近的气候和变率与真实情况高度吻合.强调了地表辐射收支分量的补偿误差,这些偏差的基本原因追溯到云、降水和辐射参数化的相关方面.模型有过于频繁产生小量级降水的倾向,这直接影响到云-辐射相互作用和地表温度的模拟.在评估由分析的边界条件驱动的高分辨率RCM时,对观测结果的使用要非常小心.当考虑到降水和云量时更是如此,因为观测的不确定性经常大于RCM的偏差.     

Brood sex ratios, female harem status and resources for nestling provisioning in the great reed warbler (Acrocephalus arundinaceus)

The theory of parental investment and brood sex ratio manipulation predicts that parents should invest in the more costly sex during conditions when resources are abundant. In the polygynous great reed warbler, Acrocephalus arundinaceus, females of primary harem status have more resources for nestling provisioning than secondary females, because polygynous males predominantly assist the primary female whereas the secondary female has to feed her young alone. Sons weigh significantly more than daughters, and are hence likely to be the more costly sex. In the present study, we measured the brood sex ratio when the chicks were 9 days old, i.e. the fledging sex ratio. As expected from theory, we found that female great reed warblers of primary status had a higher proportion of sons in their broods than females of lower (secondary) harem status. This pattern is in accordance with the results from two other species of marsh-nesting polygynous birds, the oriental reed warbler, Acrocephalus orientalis, and the yellow-headed blackbird Xanthocephalus xanthocephalus. As in the oriental reed warbler, we found that great reed warbler males increased their share of parental care as the proportion of sons in the brood increased. We did not find any difference in fitness of sons and daughters raised in primary and secondary nests. The occurrence of adaptive sex ratio manipulations in birds has been questioned, and it is therefore important that three studies of polygynous bird species, including our own, have demonstrated the same pattern of a male-biased offspring sex ratio in primary compared with secondary nests. Received: 1 June 1999 / Received in revised form: 10 January 2000 / Accepted: 12 February 2000     

Towards plant-odor-related olfactory neuroethology in Drosophila

Drosophila melanogaster is today one of the three foremost models in olfactory research, paralleled only by the mouse and the nematode. In the last years, immense progress has been achieved by combining neurogenetic tools with neurophysiology, anatomy, chemistry, and behavioral assays. One of the most important tasks for a fruit fly is to find a substrate for eating and laying eggs. To perform this task the fly is dependent on olfactory cues emitted by suitable substrates as e.g. decaying fruit. In addition, in this area, considerable progress has been made during the last years, and more and more natural and behaviorally active ligands have been identified. The future challenge is to tie the progress in different fields together to give us a better understanding of how a fly really behaves. Not in a test tube, but in nature. Here, we review our present state of knowledge regarding Drosophila plant-odor-related olfactory neuroethology to provide a basis for new progress.     

Microscale genetic differentiation in a sessile invertebrate with cloned larvae: investigating the role of polyembryony

Microscale genetic differentiation of sessile organisms can arise from restricted dispersal of sexual propagules, leading to isolation by distance, or from localised cloning. Cyclostome bryozoans offer a possible combination of both: the localised transfer of spermatozoa between mates with limited dispersal of the resulting larvae, in association with the splitting of each sexually produced embryo into many clonal copies (polyembryony). We spatially sampled 157 colonies of Crisia denticulata from subtidal rock overhangs from one shore in Devon, England at a geographic scale of ca. 0.05 to 130 m plus a further 21 colonies from Pembrokeshire, Wales as an outgroup. Analysis of molecular variance (AMOVA) revealed that the majority (67%) of genetic variation was distributed among individuals within single rock overhangs, with only 16% of variation among different overhangs within each shore and 17% of variation between the ingroup and outgroup shores. Despite local genetic variation, pairwise genetic similarity analysed by spatial autocorrelation was greatest at the smallest inter-individual distance we tested (5 cm) and remained significant and positive across generally within-overhang comparisons (<4 m). Spatial autocorrelation and AMOVA analyses both indicated that patches of C. denticulata located on different rock overhangs tended to be genetically distinct, with the switch from positive to negative autocorrelation, which is often considered to be the distance within which individuals reproduce with their close relatives or the radius of a patch, occurring at the 4–8 m distance class. Rerunning analyses with twenty data sets that only included one individual of each multilocus genotype (n = 97) or the single data set that contained just the unique genotypes (n = 67) revealed that the presence of repeat genotypes had an impact on genetic structuring (PhiPT values were reduced when shared genotypes were removed from the dataset) but that it was not great and only statistically evident at distances between individuals of 1–2 m. Comparisons to a further 20 randomisations of the data set that were performed irrespective of genotype (n = 97) suggested that this conclusion is not an artefact of reduced sample size. A resampling procedure using kinship coefficients, implemented by the software package GENCLONE gave broadly similar results but the greater statistical power allowed small but significant impacts of repeat genotypes on genetic structure to be also detected at 0.125–0.5 and 4–16 m. Although we predict that a proportion of the repeat multilocus genotypes are shared by chance, such generally within-overhang distances may represent a common distance of cloned larval dispersal. These results suggests that closely situated potential mates include a significant proportion of the available genetic diversity within a population, making it unlikely that, as previously hypothesised, the potential disadvantage of producing clonal broods through polyembryony is offset by genetic uniformity within the mating neighbourhood. We also report an error in the published primer note of Craig et al. (Mol Ecol Notes 1:281–282, 2001): loci Cd5 and Cd6 appear to be the same microsatellite. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

An Experiment with Forced Oxygenation of the Deepwater of the Anoxic By Fjord,Western Sweden

In a 2.5-year-long environmental engineering experiment in the By Fjord, surface water was pumped into the deepwater where the frequency of deepwater renewals increased by a factor of 10. During the experiment, the deepwater became long-term oxic, and nitrate became the dominating dissolved inorganic nitrogen component. The amount of phosphate in the water column decreased by a factor of 5 due to the increase in flushing and reduction in the leakage of phosphate from the sediments when the sediment surface became oxidized. Oxygenation of the sediments did not increase the leakage of toxic metals and organic pollutants. The bacterial community was the first to show changes after the oxygenation, with aerobic bacteria also thriving in the deepwater. The earlier azoic deepwater bottom sediments were colonized by animals. No structural difference between the phytoplankton communities in the By Fjord and the adjacent Havsten Fjord, with oxygenated deepwater, could be detected during the experiment.

Electronic supplementary material

The online version of this article (doi:10.1007/s13280-014-0524-9) contains supplementary material, which is available to authorized users.     

Regulating BFRs--from science to policy

An adequate distribution of responsibilities between scientists and policy-makers requires that a distinction be made between theoretical rationality (what to believe) and practical rationality (what to do). In chemical risk management, it is often necessary to base decisions on indications of risk that do not amount to full scientific proof. Guidelines are offered for how this can be done without infringing upon the integrity of science. Furthermore, it is shown that the application of standard decision theory to chemical risks yields conclusions very much in agreement with the precautionary principle.