Automated interpulse-duration assessment (AIDA): a new technique for detecting disturbances in cardiac activity in selected macroinvertebrates

An Automated Interpulse Duration Assessment system (AIDA) is described which permits detection of irregularities in cardiac rhythms in selected invertebrates. The sensitivity of AIDA was demonstrated by its ability to detect handling stress in mussels (Mytilus edulis) that was not evident when measuring heart rate alone. Changes in cardiac activity patterns of crabs (Carcinus maenas) held in the laboratory for up to 10 wk was also examined using the new technique. The frequency distribution of interpulse duration changed significantly as the nutritional state changed. Potential applications of the AIDA system are discussed.     

景观规划导向的绿色基础设施研究进展——基于“格局—过程—服务—可持续性”研究范式

中国目前处于新型城镇化与生态文明建设的重要时期,引入绿色基础设施（Green Infrastructure,GI）规划框架对协调城市发展与生态保护具有重要意义。基于景观生态学中“格局—过程—服务—可持续性”研究范式,对近年来中国内外GI规划进行针对性综述,利用该范式对相关研究的理论来源与进展进行梳理。研究表明：GI格局研究中,景观格局指数是应用最为广泛的方法。针对于景观连接度,形态学空间格局分析等结构连接度评价方法具有计算简单、适用性广的优势,但缺乏明确的生态学含义;图论等功能连接度则针对特定的生态过程,是GI格局与生态过程的重要联系,将是下一步研究重点。GI生态过程研究借鉴生态网络的理论与方法,其规划步骤可分为核心区选取、阻力面构建、潜在廊道识别三部分。GI生态系统服务研究中,生物物理量模型与经济计量模型广泛应用于调节、供给与支持服务评价中,而文化服务评价则将问卷调查作为基础数据获取的重要途径。另外,生态系统服务需求研究涉及到生态系统服务的实际需求与使用偏好,相关定量评价方法以及成果的实际应用有待进一步探索。GI景观可持续性研究中,在明晰GI提供的生态系统服务总量的基础上,服务间权衡与协同效应已成为GI规划中的重要考量,而情景规划可以有效模拟GI生态系统服务的动态变化。最后,GI规划应将提升景观可持续性作为规划目标,据此研究提出了重视格局与过程相互影响机制的基础研究、加深GI生态系统服务需求端研究、明晰生态系统服务间协同与权衡效应、将GI与实际规划结合四项研究展望。     

Risk and mitigation of self-heating and spontaneous combustion in underground coal storage

While the self-heating and spontaneous combustion of coal is a known challenge at coal mines and storage sites, there are known methods for mitigating this challenge for typical open stockpile storage. However, closing the storage will reduce access for corrective action, and it is then important to manage the storage and its transport system with added attention without unduly adding cost or hindering availability. This paper aims to discuss the risk, prevention and extinguishing of fires in closed coal storage facilities, particularly in light of the experience with the Salmisaari underground rock storage facility in Finland. The observed autoignition events have indicated an array of contributing factors, some of which are unique to underground silo storage facilities. On the other hand, many features of the storage facilities can be compared with other extant closed storage systems. The factors affecting fire risk are described and the associated fault and event trees are outlined for autoignition at underground storage. Drawing upon the experiences with past events of self-heating and spontaneous combustion, recommendations are given on cost-effective preventive, corrective and other mitigating action for minimising fire risk and promoting storage availability.     

Micromechanical Tensile Testing of Cellulose-Reinforced Electrospun Fibers Using a Template Transfer Method (TTM)

A template transfer method (TTM) and a fiber fixation technique were established for fiber handling and micro tensile stage mounting of aligned and non-aligned electrospun fiber mats. The custom-made template had been precut to be mounted on a variety of collectors, including a rapidly rotating collector used to align the fibers. The method eliminated need for direct physical interaction with the fiber mats before or during the tensile testing since the fiber mats were never directly clamped or removed from the original substrate. By using the TTM it was possible to measure the tensile properties of aligned poly(methyl methacrylate) (PMMA) fiber mats, which showed a 250?% increase in strength and 450?% increase in modulus as compared to a non-aligned system. The method was further evaluated for aligned PMMA fibers reinforced with cellulose (4 wt%) prepared as enzymatically derived nanofibrillated cellulose (NFC). These fibers showed an additional increase of 30?% in both tensile strength and modulus, resulting in a toughness increase of 25?%. The fracture interfaces of the PMMA?CNFC fibers showed a low amount of NFC pull-outs, indicating favorable phase compatibility. The presented fiber handling technique is universal and may be applied where conservative estimates of mechanical properties need to be assessed for very thin fibers.     

Prey-predator dynamics in rotifers: density-dependent consequences of spatial heterogeneity due to surface attachment

Classical models of prey-predator interactions assume that per capita prey consumption is dependent on prey density alone and that prey consumption (functional response) and consumer proliferation (numerical response) operate on the same timescales and without time lags. Several modifications have been proposed for resolving this timescale discrepancy, including variants where the functional response depends on both prey and predator densities. A microcosm system with the rotifer Brachionus 'Nevada' feeding on the prasinophyte Tetraselmis sp. showed significant (P < 0.0005) increases in steady-state biomasses of both prey and predators with increasing carrying capacity (represented by total phosphorus of the growth medium), which is inconsistent with predictions based on the traditional prey-only-dependent functional response. We provide data indicating that surfaces where the predator can attach provide a high-quality habitat for rotifers, which can result in a predator-dependent functional response. We also show that partitioning between the attached and free-swimming habitats was fast compared to the timescale of the numerical response. When attached to surfaces, rotifers maximized net energy gain by avoiding the high cost of swimming and by increased food capture due to reduced viscous drag. A mathematical model with prey-dependent functional response and wall-attached and free-swimming fractions of the population describes our data adequately. We discuss the implications of this finding for extrapolating microcosm experiments to systems with other surface-to-volume ratios, and to what extent our findings may apply to other popular model organisms for prey-predator interaction.     

Non-consumptive effects of predator presence on copepod reproduction: insights from a mesocosm experiment

Reproduction in planktonic animals depends on numerous biotic and abiotic factors. One of them is predation pressure, which can have both direct consumptive effects on population density and sex ratio, and non-consumptive effects, for example on mating and migration behaviour. In copepods, predator vulnerability depends on their sex, motility pattern and mating behaviour. Therefore, copepods can be affected at multiple stages during the mating process. We investigated the reproductive dynamics of the estuarine copepod Eurytemora affinis in the presence and absence of its predator the mysid Neomysis integer in a mesocosm experiment. We found that the proportion of ovigerous females decreased in the presence of predators. This shift was not caused by differential predation as the absolute number of females was unaffected by mysid presence. Presence of predators reduced the ratio of males to non-ovigerous females, but not by predation of males. Our combined results suggest that the shift from ovigerous to non-ovigerous females under the presence of predators was caused by either actively delayed egg production or by shedding of egg sacs. Nauplii production was initially suppressed in the predation treatment, but increased towards the end of the experiment. The proportion of fertilized females was similar in both treatments, but constantly fell behind model predictions using a random mating model. Our results highlight the importance of non-consumptive effects of predators on copepod reproduction and hence on population dynamics.     

De Novo terpenoid biosynthesis by the dendronotid nudibranch Melibe leonina

Summary. Stable isotope feeding studies using [1,2-¹³C₂]-sodium acetate have demonstrated that 2,6-dimethyl-5-heptenal (1), a putative defensive allomone, is made by the Dendronotid nudibranch Melibe leonina via de novo biosynthesis.     

Algal plating as a tool for investigating allelopathy among marine microalgae

Chemical interactions among marine microalgae were studied in cultures of pennate diatoms on agar plates. Nine marine and freshwater pennate diatoms were surveyed as potential bioassay organisms; Cylindrotheca fusiformis was most favourable for assays because of its rapid and even growth on agar. Diatom and bacterial bioassays were used to screen cell and filtrate extracts of 14 microalgal cultures. A number of these algal species, which were grown axenically, produced extractable, intracellular and/or extracellular substances that inhibited the growth of C. fusiformis. Our results suggest that the culturing of pennate diatoms on a solid medium can provide a simple bioassay for screening algal extracts which potentially contain growth inhibitors involved in microalgal allelopathy.     

Phosphorus losses from agricultural areas in river basins: effects and uncertainties of targeted mitigation measures

In this paper we show the quantitative and relative importance of phosphorus (P) losses from agricultural areas within European river basins and demonstrate the importance of P pathways, linking agricultural source areas to surface water at different scales. Agricultural P losses are increasingly important for the P concentration in most European rivers, lakes, and estuaries, even though the quantity of P lost from agricultural areas in European catchments varies at least one order of magnitude (<0.2 kg P ha(-1) to >2.1 kg P ha(-1)). We focus on the importance of P for the implementation of the EU Water Framework Directive and discuss the benefits, uncertainties, and side effects of the different targeted mitigation measures that can be adopted to combat P losses from agricultural areas in river basins. Experimental evidence of the effects of some of the main targeted mitigation measures hitherto implemented is demonstrated, including: (i) soil tillage changes, (ii) treatment of soils near ditches and streams with iron to reduce P transport from source areas to surface waters, (iii) establishment of buffer zones for retaining P from surface runoff, (iv) restoration of river-floodplain systems to allow natural inundation of riparian areas and deposition of P, and (v) inundation of riparian areas with tile drainage water for P retention. Furthermore, we show how river basin managers can map and analyze the extent and importance of P risk areas, exemplified by four catchments differing in size in Norway, Denmark, and the Netherlands. Finally, we discuss the factors and mechanisms that may delay and/or counteract the responses of mitigation measures for combating P losses from agricultural areas when monitored at the catchment scale.