Silk wrapping of nuptial gifts as visual signal for female attraction in a crepuscular spider

An extensive diversity of nuptial gifts is known in invertebrates, but prey wrapped in silk is a unique type of gift present in few insects and spiders. Females from spider species prefer males offering a gift accepting more and longer matings than when males offered no gift. Silk wrapping of the gift is not essential to obtain a mating, but appears to increase the chance of a mating evidencing a particularly intriguing function of this trait. Consequently, as other secondary sexual traits, silk wrapping may be an important trait under sexual selection, if it is used by females as a signal providing information on male quality. We aimed to understand whether the white color of wrapped gifts is used as visual signal during courtship in the spider Paratrechalea ornata. We studied if a patch of white paint on the males’ chelicerae is attractive to females by exposing females to males: with their chelicerae painted white; without paint; and with the sternum painted white (paint control). Females contacted males with white chelicerae more often and those males obtained higher mating success than other males. Thereafter, we explored whether silk wrapping is a condition-dependent trait and drives female visual attraction. We exposed good and poor condition males, carrying a prey, to the female silk. Males in poor condition added less silk to the prey than males in good condition, indicating that gift wrapping is an indicator of male quality and may be used by females to acquire information of the potential mate.     

Using unexplained variation in the chemical composition of organisms for identification of xenobiotics in ecological studies

The contents of ten metals in the bone and muscle tissues were studied in three fish species from a water body located in the impact zone of a copper smelter. In the course of principal component analysis with “tissue” and “species” taken as instrumental variables (IVs), a high proportion of unexplained IV variance was revealed for xenobiotic elements, and the procedure of optimal scaling by the CATPCA method allowed their pattern to be estimated. It is proposed to use the unexplained variance of multidimensional data on the chemical composition of organisms for identifying the pattern of xenobiotics in environmental objects.     

Ecological footprint analysis applied to a sub-national area: the case of the Province of Siena (Italy)

This work is part of a larger project, which aims at investigating the environmental sustainability of the Province of Siena and of its communes, by means of different indicators and methods of analysis. The research presented in this article uses ecological footprint and biocapacity as indicators to monitor the environmental conditions of the area of Siena, thus complementing previous studies carried out using Emergy, greenhouse gases balance and other methods. The calculations have been performed in such a way as to enable a disaggregation of the final results according to the classical categories of ecologically productive land and of consumption, but also according to citizen's and public administration's areas of influence. This information allows us to investigate in detail the socio-economic aspects of environmental resource use. Among the notable results, the Siena territory is characterized by a nearly breakeven total ecological balance, a result contrasting with the national average and most of the other Italian provinces. Furthermore, the analysis has been carried out at different spatial scales (province, districts and communes), highlighting an inhomogeneous territorial structure consisting of subareas in ecological deficit compensated by zones in ecological surplus.     

微生物菌剂强化处理油砂

研究了微生物菌剂对油砂的处理效果，并通过第15天和第30天两次追加微生物菌剂和营养物质来加速分解石油类污染物。试验结果表明，经过56d的处理，菌剂强化处理单元最终油去除率达到47．4％；添加营养物质和农家肥的对照单元油去除率为23．6％，证明土著菌种在得到适宜的营养和共代谢基质后降解了部分石油；未做任何处理的原始油砂单元含油量基本没有变化。通过气相色谱一质谱联用分析表明，微生物菌剂对于较少碳原子数的有机物质有较好的降解效果。处理单元中随着石油分解过程的进行，系统pH会有一个明显的下降过程。通过对照单元细菌数的检测发现，改善营养物质和氧含量，可以提高土著菌种的石油降解件能。     

Mesoscale ecohydrological modelling to analyse regional effects of climate change

Hydrological processes and crop growth were simulated for the state of Brandenburg (Germany) using the hydrological/vegetation/water quality model SWIM, which can be applied for mesoscale river basins or regions. Hydrological validation was carried out for three mesoscale river basins in the area. The crop growth module was validated regionally for winter wheat, winter barley and maize. After that the analysis of climate change impacts on hydrology and crop growth was performed, using a transient 1.5 K scenario of climate change for Brandenburg and restricting the crop spectrum to the three above mentioned crops. According to the scenario, precipitation is expected to increase. The impact study was done comparing simulation results for two scenario periods 2022–2030 and 2042–2050 with those for a reference period 1981–1992. The atmospheric CO₂ concentrations for the reference period and two scenario periods were set to 346, 406 and 436 ppm, respectively. Two different methods – an empirical one and a semi-mechanistic one – were used for adjustment of net photosynthesis to altered CO₂. With warming, the model simulates an increase of evapotranspiration (+9.5%, +15.4%) and runoff (+7.0%, +17.2%). The crop yield was only slightly altered under the climate change only scenario (no CO₂ fertilization effect) for barley and maize, and it was reduced for wheat (–6.2%, –10.3%). The impact of higher atmospheric CO₂ compensated for climate-related wheat yield losses, and resulted in an increased yield both for barley and maize compared to the reference scenario. The simulated combined effect of climate change and elevated CO₂ on crop yield was about 7% higher for the C₃ crops when the CO₂ and temperature interaction was ignored. The assumption that stomatal control of transpiration is taking place at the regional scale led to further increase in crop yield, which was larger for maize than for wheat and barley. The regional water balance was practically not affected by the partial stimulation of net photosynthesis due to higher CO₂, while the introduction of stomatal control of regional transpiration reduced evapotranspiration and enlarged notably runoff and ground water recharge.