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31.
Metabolic scaling,buoyancy, and growth in larval Atlantic menhaden,Brevoortia tyrannus 总被引:1,自引:0,他引:1
We measured growth of larval Atlantic menhaden, Brevoortia tyrannus in terms of mass, volume, and weight in water as well as the mass-specific activities of the metabolic enzymes citrate synthase, lactate dehydrogenase, and malate dehydrogenase. Weight in water, the force the fish must exert to maintain vertical position, increases by a factor of 18 in larvae growing from 10 to 15 mm. The weight increase coincides with the development of the larval swim bladder. The activities of all three enzymes per unit mass of fish tissue decline greatly over this time period, indicating that the fish does not further develop its aerobic and anaerobic metabolic capacity for swimming during this growth interval. 相似文献
32.
Beverley Thorpe 《Journal of Cleaner Production》2011,19(5):552-558
The Massachusetts’ Toxics Use Reduction Act (TURA) of 1989 set an important milestone in the roadmap to Clean Production. The Act’s focus on a clear definition, methodology, and mandatory planning requirements have proved successful in getting companies in Massachusetts to reduce their use of toxic chemicals in manufacturing processes. Such results are inspirational for government officials and advocacy groups attempting to reduce toxic emissions in their communities and set progressive chemicals use policies. This paper will summarize three initiatives where TURA was a catalyst and continues to impact international chemicals policy: the Sewer Use By-law in Toronto, Canada; the European Union’s REACH chemicals legislation and the international campaign by Greenpeace in Asia and Latin America to achieve zero discharge of hazardous substances into rivers. The example of Toronto and REACH show how one or more essential aspects of TURA were incorporated into legislation. In the case of REACH TURA’s requirement of mandatory planning became an important example and NGO demand during the formation of Europe’s new chemicals regulation and resulted in the first substitution assessment planning requirement in EU wide legislation. Work is now ongoing to promote TURA type legislation in Latin America and Asia. However the ability to transfer the TURA framework to regions with inadequate government oversight and cheap disposal costs is seriously hampered. Although NGO campaigns in Asian and Latin America advocate zero discharge of hazardous emissions through toxics use reduction and elimination, much training and accountability will be needed within government and companies to understand the benefits of toxics use reduction and actually implement all or parts of the TURA framework. The Toxics Use Reduction Act came into force in 1989 with high environmental awareness, an engaged citizenry and a responsive government entity. Perhaps these are the same conditions that must exist for its successful transference to industrializing countries. 相似文献
33.
Linda Stalker Prokopy Z. Asligül Göçmen Jing Gao Shorna Broussard Allred Joseph E. Bonnell Kenneth Genskow Alicia Molloy Rebecca Power 《Journal of the American Water Resources Association》2011,47(1):196-202
Prokopy, Linda Stalker, Z. Asligül Göçmen, Jing Gao, Shorna Broussard Allred, Joseph E. Bonnell, Kenneth Genskow, Alicia Molloy, and Rebecca Power, 2011. Incorporating Social Context Variables Into Paired Watershed Designs to Test Nonpoint Source Program Effectiveness. Journal of the American Water Resources Association (JAWRA) 47(1):196‐202. DOI: 10.1111/j.1752‐1688.2010.00508.x Abstract: In a traditional paired watershed study, watersheds are selected to be as similar as possible so that conclusions may be drawn about the performance of Best Management Practices. We have extended the paired watershed concept to examine the effectiveness of watershed management programs by adding comparative criteria for social characteristics. For four different 8 or 11/12 digit hydrologic unit code (HUC) watersheds in the Midwest, we have piloted a systematic method for selecting paired subwatersheds. First, we developed a list of 11 key variables. Next, a factor analysis was conducted to determine the underlying structure of the 11 input variables. Finally, in each of the four watersheds, potential paired subwatersheds (all 14 digit HUCs) were selected using the factors in a cluster analysis. Informal interviews were then held with key informants in each watershed to provide qualitative assessments of criteria that could impact the comparability of the subwatersheds. This method for selecting paired watersheds should be helpful for other researchers to test the effectiveness of watershed management programs focused on behavior change. 相似文献
34.
Heather M. Whitney Georgina Milne Sean A. Rands Silvia Vignolini Cathie Martin Beverley J. Glover 《Die Naturwissenschaften》2013,100(3):249-256
Patterns of pigmentation overlying the petal vasculature are common in flowering plants and have been postulated to play a role in pollinator attraction. Previous studies report that such venation patterning is significantly more attractive to bee foragers in the field than ivory or white flowers without veins. To dissect the ways in which venation patterning of pigment can influence bumblebee behaviour, we investigated the response of flower-naïve individuals of Bombus terrestris to veined, ivory and red near-isogenic lines of Antirrhinum majus. We find that red venation shifts flower colour slightly, although the ivory background is the dominant colour. Bees were readily able to discriminate between ivory and veined flowers under differential conditioning but showed no innate preference when presented with a free choice of rewarding ivory and veined flowers. In contrast, both ivory and veined flowers were selected significantly more often than were red flowers. We conclude that advantages conferred by venation patterning might stem from bees learning of their use as nectar guides, rather than from any innate preference for striped flowers. 相似文献
35.
36.
Turner syndrome (TS), a common chromosomal abnormality affecting females, is associated with partial or complete loss of the second sex chromosome. Although the classic karyotype is 45, X, the detection of mosaic TS is increasing. TS is a multi-system disorder with significant endocrine, cardiovascular and reproductive impacts. Accelerated ovarian follicular loss leads to primary amenorrhoea or premature ovarian insufficiency and infertility. Early diagnosis and counselling regarding hormone replacement therapy and future reproductive capacity, including fertility preservation, are essential to improve reproductive outcomes. Pubertal induction or estrogen replacement is usually required to optimise long-term health outcomes; however, initiation may be delayed due to delayed diagnosis. Spontaneous pregnancy occurs in a small number of women; however, many require donor oocytes and assisted reproductive technology to achieve a pregnancy. Pregnancy is a high risk especially when associated with congenital heart disease. Prepregnancy counselling by the multidisciplinary team (MDT) to identify contraindications and optimise pre-existing health issues is essential. Pregnancy management should be led by a maternal-fetal medicine unit with input from the MDT. This review examines reproductive health outcomes in women with TS and how best to manage them to reduce health risks and improve maternal and neonatal outcomes. 相似文献
37.
Over the last decade the Great Smoky Mountains National Park (GSMNP) has experienced a tremendous increase in visitation, especially in backcountry camping. In 1976 there were an estimated 117,500 backcountry visitor nights, with a peak of 16,865 visitor nights in April. The high use season extends from March to October. Visitation tends to be concentrated in certain sections of the park and at specific sites. The Appalachian Trail, which includes about 8 percent of the maintained trail mileage, carried 32 percent of the visitor nights in 1976.Campsite disturbance is also concentrated in specific sites and sections of the park. Maximum camping disturbance per km of maintained trail was 3,400 m2 for the sites on the Appalachian Trail. Shelter sites have more visitation per site and more total disturbance per site than open campsites, but shelters tend to have less intensive disturbance, such as bare soil, because they concentrate trampling impacts. Visitation levels were strongly correlated with disturbances such as bare soil at open campsites. Visitation was significantly correlated to the number of firepits at shelter sites but not to other types of disturbance. Regressions indicate that for each additional visitor night at a site (annual average), one can expect an additional 9 m2 of total disturbance and 1 m2of bare soil. The distance of a site from the nearest road was not significantly correlated with damage or visitation. Elevation was correlated to visitation levels, especially in the case of the shelters. More legal sites and large illegal sites are in mesic forest types. Illegal camping accounted for 10 percent of the total camping disturbance.The data imply that the suggested removal of shelters will require redistribution of visitor use or replacement developments, such as tent platforms, in order to mitigate damage. Zone camping is a possible alternative but presents difficulties because campers may concentrate in certain plant communities and topographic positions. 相似文献
38.
Linking Ecological Sustainability and World Food Needs 总被引:1,自引:0,他引:1
Alison G. Power 《Environment, Development and Sustainability》1999,1(3-4):185-196
Ecological approaches to agriculture can provide useful guidelines for addressing world food needs, while avoiding adverse environmental and social impacts. Experiments in both natural and agricultural ecosystems suggest that systems with high plant diversity may be more productive, more stable and more resilient than species-poor systems. In addition, systems with high plant diversity support higher levels of biodiversity in other functional groups, which may enhance the productivity of the plant component. Given these benefits of diverse systems, various approaches for converting conventional high input agricultural systems to more sustainable systems are addressed. Andow and Hidaka's (1989) concept of production syndromes is considered in the context of conversion to sustainable agriculture. 相似文献
39.
Thongsanit P Jinsart W Hooper B Hooper M Limpaseni W 《Journal of the Air & Waste Management Association (1995)》2003,53(12):1490-1498
Air samples of particulate matter (PM) with an aerodynamic diameter less than 10 microm (PM10) were collected from six sites in Bangkok, Thailand, using high-volume air samplers. Daily samples were taken at intervals of 12 days from November 1999 to November 2000. Size-selected sampling using a multislit Andersen size-fractionated cascade impactor was undertaken at one site in central Bangkok to identify particulate size distribution. The annual average PM10 concentration at all six sites exceeded the Thailand National Ambient Air Quality Standard (NAAQS) of 50 microg/m3. The daily PM10 concentrations at heavy traffic roadside areas ranged between 30 and 160 microg/m3. The highest PM10 level occurred during the winter period (November-February), which is the dry season. From our results, which are based on a 1-yr survey, it can be observed that the particulate concentrations are associated with traffic volumes and seasonal factors (temperature and rainfall). The relative importance of size fractions in contributing to PM load is presented and discussed. Twenty polycyclic aromatic hydrocarbons (PAHs) associated with PM have been identified and quantified. The summed PAHs based on the 20 species had an average concentration of 60 ng/m3. Benzo(e)pyrene, indeno(123cd)pyrene, and benzo(ghi)perylene were the major compounds with average concentrations of 8, 10, and 13 ng/m3, respectively. Results indicate that more than 97% of PAHs were found in the small particulate size range of <0.95 microm. 相似文献
40.
The majority of environmental effects monitoring (EEM) frameworks that have been proposed compare selected indicator variables
as a means of assessing whether significant changes in stressed ecosystems have occurred. Most are deterministic in nature
and do not appropriately account for the natural variability and dynamics within the systems being comapred. This suggests
that the comparative procedures should be statistically based and immediately raises the issue of whether the selected comparative
procedures are to be used as decision-making tools or conclusive procedures. Conclusive procedures require a significant body
of evidence before rejecting the postulated null hypothesis. The costs and time involved in environmental data collection
accordingly bias action toward the maintenance of a status quo approach to environmental management. if, however, EEM is treated
as a decision-making procedure, risk functions that include consideration of type I and II statistical error may be developed
and combined with costs to select a minimum expected loss strategy for environemental management. Examples of the interpretative
difficulties and conclusion reversal phenomena caused when EEM is used as a conclusive procedure are presented. In addition,
risk functions appropriate for environmental management within an EEM context are constructed and applied. Only when such
tools are fully developed and applied can EEM expect to have significant impacts on minimizing environmental degradation. 相似文献