Temperature effects on vital rates of different life stages and implications for population growth of Baltic sprat

Baltic sprat (Sprattus sprattus balticus S.) is a key species in the pelagic ecosystem of the Baltic Sea. Most stocks of small pelagic species are characterized by natural, fishery-independent fluctuations, which make it difficult to predict stock development. Baltic sprat recruitment is highly variable, which can partly be related to climate-driven variability in hydrographic conditions. Results from experimental studies and field observations demonstrate that a number of important life history traits of sprat are affected by temperature, especially the survival and growth of early life stages. Projected climate-driven warming may impact important processes affecting various life stages of sprat, from survival and development during the egg and larval phases to the reproductive output of adults. This study presents a stage-based matrix model approach to simulate sprat population dynamics in relation to different climate change scenarios. Data obtained from experimental studies and field observations were used to estimate and incorporate stage-specific growth and survival rates into the model. Model-based estimates of population growth rate were affected most by changes in the transition probability of the feeding larval stage at all temperatures (+0, +2, +4, +6?°C). The maximum increase in population growth rate was expected when ambient temperature was elevated by 4?°C. Coupling our stage-based model and more complex, biophysical individual-based models may reveal the processes driving these expected climate-driven changes in Baltic Sea sprat population dynamics.     

Limitations for heavy metal release during thermo-chemical treatment of sewage sludge ash

Phosphate recycling from sewage sludge can be achieved by heavy metal removal from sewage sludge ash (SSA) producing a fertilizer product: mixing SSA with chloride and treating this mixture (eventually after granulation) in a rotary kiln at 1000 ± 100 °C leads to the formation of volatile heavy metal compounds that evaporate and to P-phases with high bio-availability. Due to economical and ecological reasons, it is necessary to reduce the energy consumption of this technology. Generally, fluidized bed reactors are characterized by high heat and mass transfer and thus promise the saving of energy. Therefore, a rotary reactor and a fluidized bed reactor (both laboratory-scale and operated in batch mode) are used for the treatment of granulates containing SSA and CaCl₂. Treatment temperature, residence time and - in case of the fluidized bed reactor - superficial velocity are varied between 800 and 900 °C, 10 and 30 min and 3.4 and 4.6 m s⁻¹. Cd and Pb can be removed well (>95 %) in all experiments. Cu removal ranges from 25% to 84%, for Zn 75-90% are realized. The amount of heavy metals removed increases with increasing temperature and residence time which is most pronounced for Cu.In the pellet, three major reactions occur: formation of HCl and Cl₂ from CaCl₂; diffusion and reaction of these gases with heavy metal compounds; side reactions from heavy metal compounds with matrix material. Although, heat and mass transfer are higher in the fluidized bed reactor, Pb and Zn removal is slightly better in the rotary reactor. This is due the accelerated migration of formed HCl and Cl₂ out of the pellets into the reactor atmosphere. Cu is apparently limited by the diffusion of its chloride thus the removal is higher in the fluidized bed unit.     

Occurrence and distribution of PCB metabolites in blood and their potential health effects in humans: a review

In recent years, attention has been directed to chemicals with possible endocrine-disrupting properties. Polychlorinated biphenyls (PCBs) and their metabolites belong to one group of environmental contaminants that have been shown to interact with the endocrine system in mammals, including humans. Although recent developments have been made in terms of determination of PCB metabolites in blood samples, still limited number of studies have been able to elucidate their profiles and toxicological and health effects in humans. This review aims to evaluate and compare the levels of hydroxylated PCBs (OH-PCBs) and methyl sulfone PCBs (MeSO₂-PCBs) in blood and their relationship to parent compounds and also address the potential risks and adverse health effects in humans. Levels of OH-PCBs varied between 0.0002 and 1.6 ng g^?1 w/w in human serum/plasma from the selected literature, correlating well with ∑PCBs. In contrast, ∑OH-PCB/∑PCB ratio in animals did not show a significant correlation, which might suggest that the bioaccumulation plays an even more important role in the concentration of OH-PCBs compared to PCB metabolism. Highest levels of MeSO₂-PCBs were reported in marine mammals with high selectivity retention in the liver. Health effects of PCB metabolites included carcinogenicity, reproductive impairment, and developmental neurotoxicity, being more efficiently transferred to the brain and across the placenta from mother to fetus in comparison to the parent PCBs. Based on the lack of knowledge on the occurrence and distribution of lower chlorinated OH-PCBs in humans, further studies to identify and assess the risks associated to human exposure are essential.     

A sulfonic anhydride derivative from dibenzyl trisulphide with agro-chemical activities

In the present study, the biologically active natural product dibenzyl trisulphide (DTS) which was previously isolated from the sub-tropical shrub Petiveria alliacea was transformed to methyl benzyl sulphonic anhydride (MBSA) using a "one pot" transformation method. The anhydride was evaluated for anti-microbial activities on the bacteria, Bacillus subtilis and Pseudomonas fluorescens and found to be 2.5 fold more effective than the commercial agents isoniazid and ampicillin in inhibiting the growth of B. subtilis, while on P. fluorescens it was 2.5, 5.0 and 10.0 fold more inhibitory than isoniazid, ampicillin and dibenzyl trisulphide, respectively. DTS was inactive on B. subtillis. The MIC value (microgram/spot) found for DTS on the plant pathogenic fungus, Cladosporium cucumerinum was 5.0 microgram/spot, while MBSA gave a value of 0.1 microgram/spot, compared with 1.25 and 0.16 microgram/spot for the commercial agents ketoconazole and nystatin, respectively. On the larval nematode (Meloidogyne incognita) MBSA inflicted 97.72% and 57.47% Abbotts nematicidal activities at 125.0 and 62.5 ppm, respectively, while DTS had no effect at 125.0 ppm. Nematodes which were immobilized by the low concentrations of MBSA were unable to re-activate when exposed to 10.0 ppm picrotoxin, thus suggesting that the anhydride nematicidal activity is independent of the GABA-ergic neurophysiological pathway.MBSA demonstrated a strong dose dependent radicular suppression effect (r=0.984), on the radicles of Latuca sativa germinating seeds. DTS was weakly active.     

河岸蜘蛛——多样水生生态系统中PCB污染的指示生物

栖息在河岸的蜘蛛越来越多地被用来追踪水生生态系统中存在和流出污染物的空间格局。然而，我们对蜘蛛在何种情况下可有效标志水生污染的认识有限。本研究力证在具有高生境异质性的水生生态系统中，能够有效地利用河岸蜘蛛来追踪沉积物中多氯联苯(PCBs)污染的空间格局。2011年到2013年，在五大湖共同关注区(AOC)的Manistique河流域，对2类常见科属的河岸蜘蛛进行采样，结果表明生物体内的ΣPCB浓度的空间格局能够普遍地追踪采样点范围内沉积物中ΣPCBs的空间变化。该研究区域位于密歇根北部半岛南岸(Manistique，MI，US)，是一个河口生态系统，包括港口、河流、回水和湖泊等栖息地。沉积物ΣPCB浓度用总有机碳浓度进行归一，解释了11个采样点中41%的以脂类归一的蜘蛛ΣPCB浓度变异。此外，2类常见河岸蜘蛛类群(园蛛科Araneidae和长脚蛛科Tetragnathidae)的ΣPCB浓度高度相关(r² > 0.78)，并且按全年计算其平均ΣPCB浓度两者相似。结果表明，在异质性的水生生态系统中，例如在河流入海口，会因为栖息地和污染物变化在水生生物分类中的差别不明显，河岸蜘蛛就可能成为水生和河岸食物网中PCB有效性的标记物。此外，对于为不同种群大型结网蜘蛛提供生存条件的海岸线开发和沿岸植被的生境异质性，目前的方法具有很强的适用性。
精选自Kraus, J. M., Gibson, P. P., Walters, D. M. and Mills, M. A. (2017), Riparian spiders as sentinels of polychlorinated biphenyl contamination across heterogeneous aquatic ecosystems. Environmental Toxicology and Chemistry, 36: 1278–1286. doi: 10.1002/etc.3658
详情请见http://onlinelibrary.wiley.com/doi/10.1002/etc.3658/full
     

Abundance of the New Zealand subantarctic southern right whale population estimated from photo-identification and genotype mark-recapture

The abundance of New Zealand subantarctic southern right whales (Eubalaena australis) was estimated for the first time using mark-recapture methods based on photo-identification and microsatellite genotyping (13 loci). Individual identification photographs of 383 whales and microsatellite genotypes of 235 whales were collected during annual austral winter field surveys from 1995 to 1998. Given the 4-year survey period and lack of geographic and demographic closure, we estimated super-population abundance using the POPAN Jolly-Seber model implemented in the software programme MARK. Models with constant survivorship but time-varying capture probability and probability of entry into the population were the most suitable due to the survey design. This provided estimates of abundance in 1998 of 908 non-calf whales (95% C.L. = 755, 1,123) for the photo-identification and 910 non-calf whales (95% C.L. = 641, 1,354) for the microsatellite genotype data sets. The current estimate of 900 whales may represent less than 5% of the pre-whaling abundance in New Zealand waters.