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261.
The cost of reproduction for the terminal spawning onychoteuthid squid, Moroteuthis ingens, was analysed using measures of condition and tissue biochemistry. Both males and females showed a dramatic drop in the weight of the gonad in stage 6 (spent) individuals. The mantle weight and nidamental gland weight of females also decreased during the maturation process. Males, however, had a marked increase in both the penis and spermatophoric complex weight in spent individuals, while female oviducal gland weight and nidamental gland length also increased in stage 6 individuals. Residual analysis indicated that testis growth was not developing at the expense of mantle growth, although there was a suggestion of cost to the fins. Females showed that the development of the ovary occurred at a cost to both the mantle and fins. Overall body condition also declined with maturity stage for both males and females, with stage 6 individuals of both sexes in poor condition. Very few females had eggs in the oviducts, suggesting that the oviducts are used as ducts instead of storage organs. Proximal analysis revealed a loss of constituents within the mantle during maturation, with an associated increase in water, indicating the remobilization of energy from the mantle to fuel reproduction. This study suggests that the digestive gland is not used as an energy store in this species.Communicated by M.S. Johnson, Crawley  相似文献   
262.
Measurements and analysis of criteria pollutants in New Delhi, India   总被引:2,自引:0,他引:2  
Ambient concentrations of carbon monoxide (CO), nitrogen oxides (NOx), sulfur dioxide (SO2), and total suspended particulates (TSP) were measured from January 1997 to November 1998 in the center of downtown [the Income Tax Office (ITO) located on B.S.G. Marg] New Delhi, India. The data consist of 24-h averages of SO2, NOx, and TSP as well as 8 and 24-h averages of CO. The measurements were made in an effort to characterize air pollution in the urban environment of New Delhi and assist in the development of an air quality index. The yearly average CO, NOx, SO2, and TSP concentrations for 1997 and 1998 were found to be 4810+/-2287 and 5772+/-2116 microg/m3, 83+/-35 and 64+/-22 microg/m3, 20+/-8 and 23+/-7 microg/m3, and 409+/-110 and 365+/-100 microg/m3, respectively. In general, the maximum CO, SO2, NOx, and TSP values occurred during the winter with minimum values occurring during the summer, which can be attributed to a combination of meteorological conditions and photochemical activity in the region. The ratio of CO/NOx (approximately 50) indicates that mobile sources are the predominant contributors for these two compounds in the urban air pollution problem in New Delhi. The ratio of SO2/NOx (approximately 0.6) indicates that point sources are contributing to SO2 pollution in the city. The averaged background CO concentrations in New Delhi were also calculated (approximately 1939 microg/m3) which exceed those for Eastern USA (approximately 500 microg/m3). Further, all measured concentrations exceeded the US National Ambient Air Quality Standards (NAAQS) except for SO2. TSP was identified as exceeding the standard on the most frequent basis.  相似文献   
263.
Since the early 1990s, waste minimisation clubs have been important sources of information for industry in the UK on clean technology and sustainable waste management practice. Despite this contribution, concern has grown about the declining number of clubs, their performance and the likelihood that they will continue to play a key role in national policy.This paper examines the evidence available and provides estimates of how the numbers varied in England since the first clubs were formed. The results presented indicate that, after initial expansion, numbers went into decline. The paper then explores, using economic theory, why this pattern should have developed and suggests it to be a function of how clubs were designed and managed. The results of the analysis are used to propose alterations in how future clubs could be designed so that they continue to contribute effectively to the development of sustainable waste management in UK industry. These lessons are of value to policy in both the UK and other countries considering the development of this important tool of waste strategy. The paper concludes with a number of suggestions for future research.  相似文献   
264.
Despite the recent burgeoning in predator tracking studies, few report on seabird activity patterns, despite the potential to provide important insights into foraging ecology and distribution. In the first year-round study for any small petrel, we examined the activity patterns of the white-chinned petrel Procellaria aequinoctialis based on data from combination geolocator-immersion loggers deployed on adults at South Georgia. The petrels were highly nocturnal, flying for greater proportions of darkness than any large procellarid studied so far, except the light-mantled albatross Phoebetria palpebrata. Flight bout durations were short compared with other species, suggesting a dominant foraging mode of small-scale searching within large prey patches. When migrating, birds reduced the proportion of time on the water and increased flight bout duration. Activity patterns changed seasonally: birds flew least during the nonbreeding period, and most frequently during chick-rearing in order to meet higher energy demands associated with provisioning offspring. The degree of their response to moonlight was also stage dependent (greatest in nonbreeding, and weakest in incubating birds), a trait potentially shared by other nocturnal petrels which will have repercussions for feeding success and prey selection. For the white-chinned petrel, which is commonly caught in longline fisheries, these results can be used to identify periods when birds are most susceptible to bycatch, and therefore when use of mitigation and checking for compliance is critical.  相似文献   
265.
Brown GP  Phillips BL  Shine R 《Ecology》2011,92(2):422-431
Predicting which species will be affected by an invasive taxon is critical to developing conservation priorities, but this is a difficult task. A previous study on the impact of invasive cane toads (Bufo marinus) on Australian snakes attempted to predict vulnerability a priori based on the assumptions that any snake species that eats frogs, and is vulnerable to toad toxins, may be at risk from the toad invasion. We used time-series analyses to evaluate the accuracy of that prediction, based on >3600 standardized nocturnal surveys over a 138-month period on 12 species of snakes and lizards on a floodplain in the Australian wet-dry tropics, bracketing the arrival of cane toads at this site. Contrary to prediction, encounter rates with most species were unaffected by toad arrival, and some taxa predicted to be vulnerable to toads increased rather than declined (e.g., death adder Acanthophis praelongus; Children's python Antaresia childreni). Indirect positive effects of toad invasion (perhaps mediated by toad-induced mortality of predatory varanid lizards) and stochastic weather events outweighed effects of toad invasion for most snake species. Our study casts doubt on the ability of a priori desktop studies, or short-term field surveys, to predict or document the ecological impact of invasive species.  相似文献   
266.
We investigated the toxicity of an emerging polynitramine energetic material hexanitrohexaazaisowurtzitane (CL-20) to the soil invertebrate species Enchytraeus crypticus by adapting then using the Enchytraeid Reproduction Test (ISO/16387:2003). Studies were designed to develop ecotoxicological benchmark values for ecological risk assessment of the potential impacts of accidental release of this compound into the environment. Tests were conducted in Sassafras Sandy Loam soil, which supports relatively high bioavailability of CL-20. Weathering and aging procedures for CL-20 amended into test soil were incorporated into the study design to produce toxicity data that better reflect soil exposure conditions in the field compared with the toxicity in freshly amended soils. Concentration-response relationships for measurement endpoints were determined using nonlinear regressions. Definitive tests showed that toxicities for E. crypticus adult survival and juvenile production were significantly increased in weathered and aged soil treatments compared with toxicity in freshly amended soil, based on 95% confidence intervals. The median effect concentration (EC50) and EC20 values for juvenile production were 0.3 and 0.1 mg kg-1, respectively, for CL-20 freshly amended into soil, and 0.1 and 0.035 mg kg-1, respectively, for weathered and aged CL-20 soil treatments. These findings of increased toxicity to E. crypticus in weathered and aged CL-20 soil treatments compared with exposures in freshly amended soils show that future investigations should include a weathering and aging component to generate toxicity data that provide more complete information on ecotoxicological effects of emerging energetic contaminants in soil.  相似文献   
267.
Although United Kingdom (UK) Building Regulations applicable to houses constructed since 1992 in Radon Affected Areas address the health issues arising from the presence of radon in domestic properties and specify the installation of radon-mitigation measures during construction, no legislative requirement currently exists for monitoring the effectiveness of such remediation once construction is completed and the houses are occupied. To assess the relative effectiveness of During-Construction radon reduction and Post-Construction remediation, radon concentration data from houses constructed before and after 1992 in Northamptonshire, UK, a designated Radon Affected Area, was analysed. Post-Construction remediation of 73 pre-1992 houses using conventional fan-assisted sump technology proved to be extremely effective, with radon concentrations reduced to the Action Level, or below, in all cases. Of 64 houses constructed since 1992 in a well-defined geographical area, and known to have had radon-barrier membranes installed during construction, 11% exhibited radon concentrations in excess of the Action Level. This compares with the estimated average for all houses in the same area of 17%, suggesting that, in some 60% of the houses surveyed, installation of a membrane has not resulted in reduction of mean annual radon concentrations to below the Action Level. Detailed comparison of the two data sets reveals marked differences in the degree of mitigation achieved by remediation. There is therefore an ongoing need for research to resolve definitively the issue of radon mitigation and to define truly effective anti-radon measures, readily installed in domestic properties at the time of construction. It is therefore recommended that mandatory testing be introduced for all new houses in Radon Affected Areas.  相似文献   
268.
To identify the most applicable technology for the short-term assessment of domestic radon levels, comparative assessments of a number of integrating detector types, including track-etch, electret and activated charcoal were undertaken. Thirty-four unremediated dwellings in a high-radon area were monitored using track-etch detectors exposed for one-month and three-month periods. In parallel, one-week measurements were made in the same homes at one-month intervals, using co-located track-etch, charcoal and electret detectors exposed simultaneously, while three of the homes were also monitored by continuous-sampling detectors at hourly intervals over extended periods. Calibration of dose-integrating devices against each other and against continuous-monitoring systems confirmed good responsivity and linearity. Although track-etch, charcoal and electret devices are suitable in principle for one-week measurements, zero-exposure offset and natural radon variability cause many one-week results to be equivocal, necessitating repetition of the measurement. One-week exposures can be reliable indicators in low-radon areas or for new properties, but in high-radon areas, the use of three-month exposures is indicated. This analysis also established confidence limits for short-term measurements.  相似文献   
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