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11.
Mechanistic studies on herbivore functional responses have largely taken place in mammals; very little has been done in herbivorous birds so far. Here we aim to fill that gap by experimentally quantifying the (short-term) functional response of a large avian herbivore, the Bewick's Swan (Cygnus columbianus bewickii). We explicitly distinguish between encounter-limited and handling-limited foraging by analyzing the results in the framework of the models of D. E. Spalinger and N. T. Hobbs, originally developed for mammalian herbivory. Bite size in captive swans was experimentally manipulated by varying sward height. The time interval between two bites increased with bite size, which supports the handling-limited model (process 3) and rejects the encounter-limited models (processes 1 and 2). Subsequently, we took the obtained functional response parameters into the field in order to predict, from measurements of sward height, (1) bite sizes, (2) handling times, and (3) short-term intake rates in free-ranging swans. Indeed, for all three variables, the observed values closely matched the experimentally based predictions. Finally, we review functional response parameters available in the literature on avian herbivores and scale them allometrically in relation to mammals. This analysis revealed that maximum bite sizes, and therefore maximum intake rates, in herbivorous birds are smaller than in herbivorous mammals. We hypothesize and provide evidence that birds compensate by longer daily foraging times. 相似文献
12.
The study established waste multipliers that could be used in conjunction with the population figure of a city to estimate the quantity of solid waste generation in the developing world. Oyo, a traditional city in Nigeria was the focus of the study. Two sets of data were collected. The first was the information on the socio-economic attributes of residents obtained from 648 households through questionnaires administered using a systematic random sampling technique. The second was the measurement of waste generated in 25% of the households for a week in each of the 12 months of the year. The study established that 23.3% of the residents surveyed have educational qualifications beyond secondary school, with 51.2% engaged in occupations requiring very little or no formal education and 50.9% were in the low-income group. The daily per capita solid waste generation was 0.129 kg. The highest (9.8%) and lowest (6.5%) of the annual quantities of waste were produced in October and February, respectively. Similarly, 20.2% of the weekly generation was produced on Saturday and the 10.2% produced on Thursday was the lowest. Animal dung, which accounted for 18.0%, constituted the highest component of the total solid waste generated. The study further established that the organic component of the waste generation was 75.4%. The results of the regression analysis R2 significant at 0.001 showed that income, household size, social status, occupation, education and season of the year explained 88.8% of waste generation in Oyo. It was established that 50.90 tonnes of solid waste was generated per day in the city in 2005, and the daily generation in the year 2008 is estimated to be 55.20 tonnes. The study concluded that with an average annual population growth of 13 000 people for the town, an additional 1.3 acres of land will need to be legally acquired annually, implying that 10.92-19.68 hectares ill be required as dump site(s) over the next 20-30 years. 相似文献
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Abel Wolman 《Journal of the American Water Resources Association》1986,22(6):895-901
The following paper was presented by Dr. Abel Wolman at the Plenary Session of the 22nd Annual Conference of the American Water Resources Association in Atlanta, Georgia, November 10, 1986. Dr. Wolman is Professor Emeritus of Sanitary Engineering at The Johns Hopkins University. He was educated at Johns Hopkins and has received an Honorary Doctor of Engineering (1937) and Honorary Doctor of Laws (1969) from his alma mater. Dr. Wolman held a number of positions before joing the faculty of The Johns Hopkins University as Professor and Chairman of the Department of Sanitary Engineering (1937–1959). He has served as consultant for many studies and projects, in the United States and overseas, and has a long-term record of service to communities, states and governments. A long list of awards and honors include the Sedgwick Memorial Award, APHA; Arthur Sidney Bedell Award, WPCF; Hemisphere Award, inter-American Association of Sanitary Engineers; U.S. Award of the National Medal of Science; Tyler Award, Ecological Society of America; Ben Gurion Award from the State of israel; and the Gordon Maskew Fair Award, WPCA. He is author, co-author or editor of four books and over 3000 technical publications, most in refereed journals. 相似文献
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The Science of Nature - 相似文献
16.
Stefan Gelcich Francisca Amar Abel Valdebenito Juan Carlos Castilla Miriam Fernandez Cecilia Godoy Duan Biggs 《Ambio》2013,42(8):975-984
Tourism is a financing mechanism considered by many donor-funded marine conservation initiatives. Here we assess the potential role of visitor entry fees, in generating the necessary revenue to manage a marine protected area (MPA), established through a Global Environmental Facility Grant, in a temperate region of Chile. We assess tourists’ willingness to pay (WTP) for an entry fee associated to management and protection of the MPA. Results show 97 % of respondents were willing to pay an entrance fee. WTP predictors included the type of tourist, tourists’ sensitivity to crowding, education, and understanding of ecological benefits of the MPA. Nature-based tourists state median WTP values of US$ 4.38 and Sun-sea-sand tourists US$ 3.77. Overall, entry fees could account for 10–13 % of MPA running costs. In Chile, where funding for conservation runs among the weakest in the world, visitor entry fees are no panacea in the short term and other mechanisms, including direct state/government support, should be considered. 相似文献
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Abel TD 《Environmental management》2008,42(2):232-248
This article presents a case study of Toxics Release Inventory (TRI) air pollution exposure risks across metropolitan St. Louis. The first section critically reviews environmental justice research and related barriers to environmental risk management. Second, the paper offers a conventional analysis of the spatial patterns of TRI facilities and their surrounding census block group demographics for metropolitan St. Louis. Third, the article describes the use of an exposure risk characterization for 319 manufacturers and their air releases of more than 126 toxic pollutants. This information could lead to more practical resolutions of urban environmental injustices. The analysis of TRIs across metropolitan St. Louis shows that minority and low-income residents were disproportionately closer to industrial pollution sources at nonrandom significance levels. Spatial concentrations of minority residents averaged nearly 40% within one kilometer of St. Louis TRI sites compared to 25% elsewhere. However, one-fifth of the region's air pollution exposure risk over a decade was spatially concentrated among only six facilities on the southwestern border of East St. Louis. This disproportionate concentration of some of the greatest pollution risk would never be considered in most conventional environmental justice analyses. Not all pollution exposure risk is average, and the worst risks deserve more attention from environmental managers assessing and mitigating environmental injustices. 相似文献
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Toxicity of cassava effluent in water on aquatic lives was examined via acute and chronic bioassay experiments on Clarias gariepinus (I) and Oreochromis niloticus (II) under laboratory conditions, using standard procedures. The effluent cyanide concentration exceeded the WHO limit for wastewater. Fish body weights and haematological parameters (HMP) significantly decreased with increasing effluent concentration at p≤0.05. Toxicity on HMP for the respective (I) and (II) varied from 5.4 to 52.8; 4.8 to 51.9% for packed cell volume, 4.1 to 43.9; 5.3 to 64.0% for red blood count, 0.0 to 15.7; 0.0 to 61.4% for white blood count, 3.6 to 45.9; 5.2 to 49.5% for haemoglobin, 11.6 to 71.9; 28.4 to 63.8% for total protein, 11.5 to 75.5; 15.0 to 58.2% for albumin and 11.8 to 75.0; 46 to 83.9% for globulin. Acute exposure yielded 96-h LC50 values of 0.45% for (I) and 0.25% for (II) and chronic exposure caused reduced growth and poor blood quality. 相似文献
20.
Sources and major biogeochemical pathways of organic matter in the mangrove system of Rufiji estuary
Daniel Abel Shilla 《Chemistry and Ecology》2019,35(6):524-536
Fatty acids were extracted from the surface sediments (10 cm) of three sampling sites of Rufiji estuary to infer their sources and biogeochemical pathways. The fatty acids ranging from C8 to C24 were distinguished from this study, and were broadly classified into saturated (SFAs), monounsaturated (MUFAs) and polyunsaturated fatty acids (PUFAs). SFAs were found to be the major fraction at station 1 and 3 where as at station 2, MUFAs dominated. A total of 19 fatty acids with a total concentration of 64.91 μg/g dry weight were characterised at station 1. C16:0 was the most abundant fatty acid contributing 21.94% of total fatty acids (TFAs). C22:2 was the second most abundant, which accounted for 9.46% of TFAs. Fatty acids ranging from C12 to C24 were identified at station 2. C20 fatty acid was the most abundant fatty acid contributing 21.94%, followed by C16:0. At station 3, fatty acids ranging from C8 to C24 were obtained. The PUFA C20:5n-3 was the most abundant fatty acid contributing 21.65%, followed by C24:0 (15.00% of TFAs). The ratio of lower molecular weight (LMW) to higher molecular weight (HMW) biomarkers was used as an indicators to distinguish higher plants organic matter from algae-derived fatty acids. 相似文献