From interference to predation: type and effects of direct interspecific interactions of small mammals

Indirect exploitative competition, direct interference and predation are important interactions affecting species coexistence. These interaction types may overlap and vary with the season and life-history state of individuals. We studied effects of competition and potential nest predation by common shrews (Sorex araneus) on lactating bank voles (Myodes glareolus) in two seasons. The species coexist and may interact aggressively. Additionally, shrews can prey on nestling voles. We studied bank vole mothers’ spatial and temporal adaptations to shrew presence during summer and autumn. Further, we focused on fitness costs, e.g. decreased offspring survival, which bank voles may experience in the presence of shrews. In summer, interference with shrews decreased the voles’ home ranges and they spent more time outside the nest, but there were no effects on offspring survival. In autumn, we found decreased offspring survival in enclosures with shrews, potentially due to nest predation by shrews or by increased competition between species. Our results indicate a shift between interaction types depending on seasonal constraints. In summer, voles and shrews seem to interact mainly by interference, whereas resource competition and/or nest predation by shrews gain importance in autumn. Different food availability, changing environmental conditions and the energetic constraints in voles and shrews later in the year may be the reasons for the varying combinations of interaction types and their increasing effects on the inclusive fitness of bank voles. Our study provides evidence for the need of studies combining life history with behavioural measurements and seasonal constraints.     

A procedure for generating synthetic weather records in conjunction of climatic scenario for modelling of ecological impacts of changing climate in boreal conditions

A simulation procedure for the calculation of temperature, cloudiness, radiation, precipitation, air humidity, windiness and atmospheric carbon is presented. The procedure generates the hourly or daily values of the weather factors based on long-term weather statistics. The basic factor behind the weather pattern indicated by different weather factors is air temperature, which modifies the cloudiness produced by a stochastic process in other respects. Consequently, the radiation and precipitation coming onto a site and the air humidity are also modified by temperature. This facilitates the future weather patterns to be calculated on the basis of the temperature increase allowing to introduce the effect of the suggested climatic change also into the other weather factors, assuming that the basic variability of the weather factors remains unchanged. The future windiness is calculated as random process without correlation to other weather factors.     

Degradation of 1,2-dichloroethane from wash water of ion-exchange resin using Fenton’s oxidation

Background, aim, and scope  

Chlorinated volatile organic compounds (CVOCs), widely used in industry as solvents and chemical intermediates in the production of synthetic resins, plastics, and pharmaceuticals, are highly toxic to the environment and public health. Various studies reported that Fenton’s oxidation could degrade a variety of chlorinated VOCs in aqueous solutions. In acidic conditions, ferrous ion catalyzes the decomposition of H₂O₂ to form a powerful ^•OH radical. In this study, wastewater from wash of ion-exchange resin containing typical CVOC, 1,2-dichloroethane, was treated using Fenton’s oxidation. To reduce environmental load and processing costs of wastewater, Fenton process as a simple and efficient treatment method was applied to degrade 1,2-dichloroethane of wash water.     

PCDD/F and PCB history in dated sediments of a rural lake

Concentrations of polychlorinated dibenzo-p-dioxins (PCDD), dibenzofurans (PCDF) and biphenyls (PCB) were analysed from a sediment core, which had been sampled from a remote lake in Finland. The deepest subsamples were analysed from a depth of 4.0 m, and were more than 8000 years old. At the surface of the sediment core, low levels of industrial background contamination were detected. The sum of 2,3,7,8-substituted PCDD/Fs was 35 ng/kg d.w. (dry weight), or 1.2 ng/kg d.w. in WHO's toxicity equivalent, WHO-TEQ. The annual accumulation rate of 2,3,7,8-substituted PCDD/Fs was 1.26 ng m(-2) a(-1). Deeper in the core, PCDD/F concentrations ranged between 2.11 and 11.1 ng/kg d.w. (0.24 and 1.70 ng/kg d.w. WHO-TEQ) and the accumulation rate was 0.11 ng m(-2) a(-1). A characteristic PCDD/F congener profile was found in all pre-industrial sediment layers. The order of concentrations was OCDD > 1,2,3,4,6,7,8-HpCDD > 1,2,3,7,8,9-HxCDD > 1,2,3,4,7,8-HxCDD > 2,3,7,8-TCDD, and concentrations of 2,3,7,8-chlorinated dibenzofurans were below the detection limit. Similar congener profiles have previously been described in samples for which natural PCDD/F formation has been proposed. PCBs were present at low levels in all of the sediment samples. The sum of the PCB concentrations of the sediment subsamples ranged between 50 and 2540 ng/kg d.w., and the three predominant congeners in the core were PCBs 18, 52, and 110.     

Polychlorinated dibenzo-p-dioxins, dibenzofurans, and biphenyls in the general population in Finland

We measured adipose tissue concentrations of polychlorinated dibenzo-p-dioxins, dibenzofurans (PCDD/Fs), and polychlorinated biphenyls (PCBs) in 420 general Finns living in southern Finland. The mean (median) concentrations of WHO(PCDD/F)-TEQ and WHO(PCB)-TEQ were 29.0 (24.1) and 20.7 (16.7) pg g-1 fat, respectively. The concentrations clearly correlated with age. Expressing the concentrations as a function of subject's ages revealed that the exposure of Finns has declined over the last 30 years. A downward gradient was found in the concentrations from the Baltic Sea coast to inland areas in Finland, and this was assessed to be due to consumption of the Baltic Sea fish, especially Baltic herring. Linear regression models for natural logarithm WHO(PCDD/F)-TEQ, natural logarithm WHO(PCB)-TEQ, and natural logarithm WHO(total)-TEQ, explained 70%, 69%, and 72% of the variability, respectively. Age, lactation, place of residence, and fish consumption frequencies were significant predictors in the models.     

Sampling procedure for the foliar analysis of deciduous trees

Sampling can be the source of the greatest errors in the overall results of foliar analysis. This paper reviews the variability in heavy metal concentrations in tree crowns, which is a feature that should be known and understood when designing a suitable leaf sampling procedure. The leaf sampling procedures applied in 75 articles were examined. Most of the environmental studies used a closely related form of the UN/ECE-EC leaf sampling procedure, which was developed for the long-term monitoring of forest condition. Studies with objectives outside the UN/ECE-EC field of application should utilize a sampling procedure that is in accordance with the objectives of the study and based on the observed variation in pilot and similar studies. The inherent sources of heavy metal variability inside the stand, i.e. the crown class, stand management, site properties, crown dimensions, infections, seasons, etc. were discussed, but the underlying causes of this variability are rarely understood. The inherent variability in tree crowns is the reason for using leaf sampling as a tool in pollution studies. The objectives of a pollution study determine which sources of variability are utilized by the researcher.     

Amniotic fluid pregnancy-specific β1-glycoprotein (SP1) in fetal developmental disorders

Concentration of pregnancy-specific β1-glycoprotein (SP1) was studied in second and third trimester amniotic fluid from pregnancies with various fetal developmental disorders. The material consisted of 26 cases with chromosomal disorders and 19 cases with nonchromosomal fetal malformations. The SP1 concentration was elevated in two cases of Meckel's syndrome (mean + 2.7–4.0 S.D.) as well as in one case of fetal triploidy (mean + 22 S.D.), while it was normal in all other 14 different fetal disorders.     

Amniotic fluid pregnancy-specific β1-glycoprotein (SP1) in Meckel's syndrome: A new test for prenatal diagnosis?

Amniotic fluid levels of pregnancy-specific β₁-glycoprotein (SP₁) were elevated in four pregnancies with Meckel's syndrome at 16 and 26 weeks, and the levels of hCG were also elevated in three out of four cases. These findings suggest a potential new application of SP₁ measurement for prenatal diagnosis.     

Is the antipredatory response in behaviour reflected in stress measured in faecal corticosteroids in a small rodent?

Predation risk has been shown to alter various behaviours in prey. Risk alters activity, habitat use and foraging, and weight decrease might be a consequence of that. In mammals, studies on physiological measures affected by risk of predation, other than weight, are rare. We studied in two separate laboratory experiments foraging, hoarding behaviour and expression of stress measured non-invasively from the faeces in the bank vole (Clethrionomys glareolus), a common boreal rodent. Voles were exposed to predation risk using odours of the least weasels (Mustela nivalis nivalis). Distilled water served as control. In the first experiment, we found that foraging effort, measured as sunflower seeds taken from seed trays filled with sand, was significantly lower in trays scented with weasel odour. Both immediate consumption of seeds and hoarding were affected negatively by the weasel odour. Females hoarded significantly more than males in autumn. In the second experiment, the negative effect of weasel odour on foraging was consistent over a 3-day experiment, but the strongest effect was observed in the first night. Foraging increased over the time of the experiment, which might reflect either energetic compensation during a longer period of risk, predicted in the predation risk allocation hypothesis, or habituation to the odour-simulated risk. Despite decreased foraging under predation risk, stress measured as corticosteroid metabolite concentration in vole faeces was not affected by the weasel odour treatment. In conclusion, we were able to verify predation-risk-mediated changes in the foraging effort of bank voles but no physiological stress response was measured non-invasively, probably due to great individual variation in secretion of stress hormones.