Mating and its effect on acoustic signalling behaviour in a primitive orthopteran,Cyphoderris strepitans (Haglidae): the cost of feeding females

Summary Males of the primitive orthopteran, Cyphoderris strepitans, provide their mates with two types of nuptial food gift during mating: 1) females feed while coupled on the fleshy metathoracic wings of the male and the resultant flow of haemolymph and 2) the spermatophore transferred by the male includes a gelatinous spermatophylax which the female eats after mating. During the peak breeding interval, virgin males secure significantly more matings than their numbers relative to non-virgin males would predict. We tested the hypothesis that non-virgin males, having lost a substantial portion of available energy through previous investment in females, call significantly less than virgin males. Reduced calling should result in the attraction of fewer females and/or a greater risk of intrusion from competing males and consequently, a lowered mating success. Calling activity of male C. strepitans of varying mating status was monitored with a sound activated relay apparatus for two consecutive nights following their capture. Males were of three experimental groups, virgin, freshly wounded males (mated on the same night of capture), and old-wound males (mated at least one night prior to capture). Our cata showed a significant short-term reduction in signalling activity as a consequence of mating. Whereas there was no difference in the time spent calling by virgins on the first and second nights following capture, freshly wounded and oldwound males called significantly less on the first night than on the second. Furthermore, the proportion of males calling on both nights was significantly greater for the virgin and old-wound groups than for freshly wounded males. When the duration over which males called on the first night was compared with that of the second, virgin males showed no difference whereas old-wound males called for significantly shorter intervals on the first night. These results indicate that the cost of a large nutrient investment in females lowers the energy level in males below the threshold required for a prolonged signalling period. After a refractory interval during which males feed and replenish their energy reserves, calling levels equivalent to those which occur prior to mating are regained. Active female choice may also contribute to the reduced mating success of non-virgins, but this possibility remains untested.     

Transfer of radioactive caesium from soil to vegetation and comparison with potassium in upland grasslands

The distribution and transfer of caesium and potassium between soils and vegetation has been investigated by field sampling and experimental studies on soils and vegetation typical of upland grassland in north west England. Total (137)Cs content to a depth of 0.05 m below root matt ranged from 13 000 to 18 000 Bq m(-2). This caesium content derives from three sources: the Windscale accident of 1957, weapons-testing fallout which peaked in the early 1960s, and the Chernobyl accident in May 1986. From 2200 to 6200 Bq m(-2) is attributed to the first two sources, and the remainder to Chernobyl. In December 1986, 23-78% of pre-Chernobyl (137)Cs was associated with soil underlying root matt and 0.5-5.5% was associated with vegetation. Plant/soil concentration ratios for pre-Chernobyl (137)Cs were in the range 0.5-6.5, the lowest values being associated with patches of Festuca/Agrostis turf. At the same time, 4-19% of (137)Cs deposited from Chernobyl was associated with vegetation, although higher values appeared in conjunction with the moss, Polytrichum commune. Corresponding total potassium contents were in the range 9.6-22 mg m(-2) to 0.05 m soil depth. Lower values were found at the wetter sites where, on average, 5.7% of the total potassium was present in vegetation. At drier sites the potassium content was higher and, on average, 8.9% was present in vegetation. Plant/soil concentration ratios ranged from 2.2 to 9.2. During accelerated growth of vegetation, on monoliths in glasshouse conditions over the winter of 1986/87, (137)Cs was transferred from soil and root matt to new growth, such that concentrations in fresh growth were similar to or higher than those observed in the field during December 1986. Removal of caesium by successive cuts resulted in up to 25% of the original estimated total being removed over a 240 day period. Increased concentrations coincided with the emergence of Carex sp. and Trichophorum caespitosum, as well as the development of Agrostis sp. and Festuca ovina. Observed Cs/K discrimination ratios, particularly for (137)Cs deposited from Chernobyl, were higher than previously reported in the literature. The experimental results were confirmed by field observations during spring 1987 and it is concluded that caesium deposited as a result of the Chernobyl accident will continue to be recycled in organic and low potassium soils.     

Nocturnal changes in the mean length of a euphausiid population: vertical migration,net avoidance,or experimental error?

The lengths of 9 421 Antarctic krill, Euphausia superba Dana, from 144 net samples from 4 depth ranges at the same location (north east of South Georgia) were measured over a period of 6 d. While the mean lengths showed differences between each depth range in each time period of each day, the only consistent difference occurred in the period 00.00 to 04.00 hrs local time, when the mean lengths of krill were up to 2 mm greater than those found at other times. While vertical migration may have contributed to this nocturnal change in mean length, differences in measurement techniques between observers were also implicated. Controlled laboratory experiments confirmed that there were significant differences between measurements of the same krill analysed by six different observers while there were no significant differences in replicate measurements made by a single observer. These results have important implications for future studies involving length and length-frequency analysis, and suitable precautions and experimental protocols are suggested.     

A weight-adjusted Peto’s test when cause of death is not assigned

A new statistical testing approach using a weighted logrank statistic is developed for rodent tumorigenicity assays that have a single terminal sacrifice but not cause-of-death data. Instead of using cause-of-death assignment by pathologists, the number of fatal tumors is estimated by a constrained nonparametric maximum likelihood estimation method. For data lacking cause-of-death information, the Peto test is modified with estimated numbers of fatal tumors and a Fleming–Harrington-type weight, which is based on an estimated tumor survival function. A bootstrap resampling method is used to estimate the weight function. The proposed testing method with the weight adjustment appears to improve the performance in various situations of single-sacrifice animal experiments. A Monte Carlo simulation study for the proposed test is conducted to assess size and power of the test. This testing approach is illustrated using a real data set.     

Concentrations of Mn,Fe, Cu,Zn and Cd in the mesopelagic decapod Systellaspis debilis from the East Atlantic Ocean

Specimens of the oceanic decapod Systellaspis debilis were collected from six sites in the East Atlantic Ocean between 1970 and 1984, and were analysed for Mn, Fe, Cu, Zn and Cd. The data confirm that there are small but significant differences in mean metal concentrations from some sites which showed no obvious pattern in relation to geographic location of the samples. As a result, ranges of site means are quoted as baseline levels for each metal (g g^-1 dry wt): 2.3 to 2.9 g Mn g^-1, 31.2 to 77.8 g Fe g^-1, 25.9 to 83.4 g Cu g^-1, 41.9 to 92.9 gZn g^-1, 11.1 to 31.8 g Cd g^-1. The concentration of cadmium in S. debilis from all sites was raised relative to cadmium concentrations reported for coastal decapods, perhaps as a result of dietary enrichment. Metal accumulation may provide useful information for understanding the complex feeding behaviour of many oceanic animals.     

Modeling methane oxidation in landfill cover soils as indicator of functional stability with respect to gas management

A performance-based method for evaluating methane (CH₄) oxidation as the best available control technology (BACT) for passive management of landfill gas (LFG) was applied at a municipal solid waste (MSW) landfill in central Washington, USA, to predict when conditions for functional stability with respect to LFG management would be expected. The permitted final cover design at the subject landfill is an all-soil evapotranspirative (ET) cover system. Using a model, a correlation between CH₄ loading flux and oxidation was developed for the specific ET cover design. Under Washington’s regulations, a MSW landfill is functionally stable when it does not present a threat to human health or the environment (HHE) at the relevant point of exposure (POE), which was conservatively established as the cover surface. Approaches for modeling LFG migration and CH₄ oxidation are discussed, along with comparisons between CH₄ oxidation and biodegradation of non-CH₄ organic compounds (NMOCs). The modeled oxidation capacity of the ET cover design is 15 g/m²/day under average climatic conditions at the site, with 100% oxidation expected on an annual average basis for fluxes up to 8 g/m²/day. This translates to a sitewide CH₄ generation rate of about 260 m³/hr, which represents the functional stability target for allowing transition to cover oxidation as the BACT (subject to completion of a confirmation monitoring program). It is recognized that less than 100% oxidation might occur periodically if climate and/or cover conditions do not precisely match the model, but that residual emissions during such events would be de minimis in comparison with published limit values. Accordingly, it is also noted that nonzero net emissions may not represent a threat to HHE at a POE (i.e., a target flux between 8 and 15 g/m²/day might be appropriate for functional stability) depending on the site reuse plan and distance to potential receptors.

Implications: This study provides a scientifically defensible method for estimating when methane oxidation in landfill cover soils may represent the best available control technology for residual landfill gas (LFG) emissions. This should help operators and regulators agree on the process of safely eliminating active LFG controls in favor of passive control measures once LFG generation exhibits asymptotic trend behavior below the oxidation capacity of the soil. It also helps illustrate the potential benefits of evolving landfill designs to include all-soil vegetated evapotranspirative (ET) covers that meet sustainability objectives as well as regulatory performance objectives for infiltration control.     

Development and application of protocols for the determination of response of real-time particle monitors to common indoor aerosols

Protocols have been developed and applied for the generation of aerosols that are likely to be comparable to those encountered in field settings for the calibration of easily transportable/portable real-time particle monitors. Aerosols generated were simulated environmental tobacco smoke, cedar wood smoke, cooking oil fumes, and propane stove particles. The time-integrated responses of three nephelometers and a monitor for particle-bound polynuclear aromatic hydrocarbons (PAH) were compared with gravimetric respirable suspended particulate matter (RSP) in a controlled-atmosphere chamber. In general, the monitor responses increased linearly with increasing mass concentration. However, the two monitors that reported mass per volume concentrations tended to overreport the actual RSP concentrations by factors up to 4.4. The real-time PAH monitor did not respond to cooking oil fumes, indicative of little PAH being present in the aerosol. One of the monitors that has been used in a variety of studies reported in the literature (DustTrak) was collocated with gravimetric RSP samplers in several hospitality venues in the Louisville, KY, area. Field studies indicated that the units overreported actual RSP concentrations by factors of 2.6-3.1, depending on whether the sampling was conducted in the nonsmoking or smoking sections of the facilities.     

The concept of light intensity adaptation in marine phytoplankton: Some experiments with Phaeodactylum tricornutum

The historical background on adaptation of algae to various light intensities is analysed. It is argued that there is little evidence to suggest that previous growth at low light intensities enhances the ability of an alga to utilize these low light levels. Rather, the published evidence suggests that the most general response to growth at sub-optimal light intensities is a reduced ability to utilize saturating levels. The present experiments with Phaeodactylum tricornutum Bohlin have tested this concept of light intensity adaptation. Changing photosynthetic abilities during batch growth depended on the light intensity used for growth and these changes affected interpretations of the data. When measurements were made intensities appeared to photosynthesize (at all intensities) better than did those grown at higher light levels. When the changes during batch growth were taken into account, or when the alga was grown in turbidostat cultures, a different picture was obtained. Growth at reduced light intensities was accompanied by (a) increased chlorophyll content, (b) decreased rate of light-saturated photosynthesis expressed on a chlorophyll, cell number or cell protein basis, and (c) decreased activity of RuDP carboxylase. One result suggested that growth at a suboptimal light intensity did enhance the ability to utilize lower light levels. The light-saturation curve of cells grown in batch culture at 0.7 klux showed higher slopes at the low light intensities than did those grown at 12 klux. This was most marked when photosynthesis was expressed per cell, but was also apparent when it was put on a per chlorophyll basis.     

PREDICTING CHANGE IN NON-LINEAR SYSTEMS

Complex systems are characterizedby surprising switches to new behaviours. Evaluating and predicting these changes demands anunderstanding of the behaviour of the whole system. The combined ecosystem-climate system shows chaoticor pseudorandom behaviour, stochastic or trulyrandom behaviour, as well as simple bifurcation andsemi-stability. Semistability involves the suddenchange from a destabilized attractor to a newstable attractor which may occur after an apparentlyunpredictable time delay. We present some recentresults for analyzing time series data and for usingsimulations of non-linear models to predict these changes.     

Interdisciplinary studies on the technical and economic feasibility of deep underground coal gasification with CO<Subscript>2</Subscript> storage in bulgaria

This paper presents the outcome of a feasibility study on underground coal gasification (UCG) combined with direct carbon dioxide (CO₂) capture and storage (CCS) at a selected site in Bulgaria with deep coal seams (>1,200 m). A series of state-of-the-art geological, geo-mechanical, hydrogeological and computational models supported by experimental tests and techno-economical assessments have been developed for the evaluation of UCG-CCS schemes. Research efforts have been focused on the development of site selection requirements for UCG-CCS, estimation of CO₂ storage volumes, review of the practical engineering requirements for developing a commercial UCG-CCS storage site, consideration of drilling and completion issues, and assessments of economic feasibility and environmental impacts of the scheme. In addition, the risks of subsidence and groundwater contamination have been assessed in order to pave the way for a full-scale trial and commercial applications. The current research confirms that cleaner and cheaper energy with reduced emissions can be achieved and the economics are competitive in the future European energy market. However the current research has established that rigorous design and monitor schemes are essential for productivity and safety and the minimisation of the potential environmental impacts. A platform has been established serving to inform policy-makers and aiding strategies devised to alleviate local and global impacts on climate change, while ensuring that energy resources are optimally harnessed.