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131.
Abstract: Illegal exploitation threatens the survival of many species, and anti-poaching legislation ("protection on paper") does not protect species. State enforcement is needed to support and supplement the formal status of endangered species, but state enforcement can be a source of instability leading to the demise of species if ad hoc rules are followed blindly. We demonstrate this with a model of poaching, wildlife, and government wildlife enforcement, but our findings apply more generally. Crucial assumptions of the dynamic model are that both poaching and enforcement effort increase or decrease whenever poaching effort and enforcement are relatively profitable or unprofitable activities, respectively. We found that multiple steady states may characterize the system's equilibrium. Depending on initial populations, the initial extent of state involvement, and random events, animal populations may be severely depleted or unexpectedly built up during transition phases. Our findings highlight the importance of history and luck in protecting endangered species. 相似文献
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Sung Kim Chen Zhao Allan T. Bombard Charles Cantor Dirk van den Boom Cosmin Deciu 《黑龙江环境通报》2013,33(13):1310-1313
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J. Van Caneghem C. Block P. Cramm R. Mortier C. Vandecasteele 《Journal of Cleaner Production》2010,18(8):807-814
In addition to CO2 released by the combustion of fossil fuel and leading to climate change, large steelworks emit pollutants that have other environmental impacts. ArcelorMittal Gent, an integrated steelwork producing ca. 5 × 106 tons of steel per year, not only decreased its specific energy consumption and CO2-emissions, but also reduced the environmental impact of its other emissions. This is illustrated by means of the evolution of 6 partial eco-efficiency indicators for the impact categories acidification, photo-oxidant formation, human toxicity, freshwater aquatic ecotoxicity, eutrophication and water use. The partial eco-efficiency indicators are eco-intensities, defined as the environmental impact in the respective impact category, divided by the amount of liquid steel produced. In the period 1995 – 2005 these indicators decreased by 45, 4, 52, 9, 11 and 33% respectively, whereas the steel production increased by 17%. The net impact of discharges of wastewater is negligible for human toxicity and is negative (concentrations lower than in the canal water used) for freshwater aquatic toxicity and eutrophication. For acidification, human toxicity (only emissions to air) and water use, the decoupling between environmental impact and production was absolute; for photo-oxidant formation, freshwater aquatic ecotoxicity (only emissions to air) and eutrophication, it was relative. 相似文献
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The influence of 10 wt.% mature compost was tested on the heavy metal leachate emissions from a calcium-rich municipal solid waste incineration air pollution control residue (MSWI APC). Apart from elongated columns (500 and 1250 mm), an otherwise norm compliant European percolation test setup was used. More than 99% of the metals Al, As, Cd, Cr, Cu, Fe and Ni were left in the APC residue after leaching to a liquid-to-solid ratio (L/S) of 10. Apparent short-term effects of elevated leachate DOC concentrations on heavy metal releases were not detected. Zn and Pb leachate concentrations were one order of magnitude lower for L/S 5 and 10 from the pure APC residue column, which suggests a possible long-term effect of compost on the release of these elements. Prolonging the contact time between the pore water and the material resulted in elevated leachate concentrations at L/S 0.1 to L/S 1 by a factor of 2. Only Cr and Pb concentrations were at their maxima in the first leachates at L/S 0.1. Equilibrium speciation modelling with the PHREEQC code suggested portlandite (Ca(OH)2) to control Ca solubility and pH. 相似文献
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Susanne P. A. den Boer Jacobus J. Boomsma Boris Baer 《Behavioral ecology and sociobiology》2008,62(12):1843-1849
The seminal fluid that accompanies sperm in ejaculates has been shown or suggested to affect sperm competition and paternity
success of insects by preventing female remating, inducing oviposition, and forming mating plugs. In Atta leafcutter ants, queens have multiple mates but never remate later in life, although they may live and produce fertilized
eggs for several decades. The mating biology and life history of these ants therefore suggests that the major function of
seminal fluid is to maximize sperm viability during copulation, sperm transfer, and initial sperm storage. We tested this
hypothesis by comparing the viability of testis sperm and ejaculated sperm (mixed with seminal fluid) and found a significant
positive effect of seminal fluid on sperm viability. We further quantified this positive effect by adding accessory gland
secretion (a major component of seminal fluid) in a dilution series, to show that minute quantities of accessory gland secretion
achieve significant increases in sperm viability. Sperm stored by queens for 1 year benefited in a similar way from being
exposed to accessory gland compounds after dissection in control saline solution. Our results provide the first empirical
evidence that seminal fluid is important for the production of viable ejaculates and that the accessory glands of Atta males—despite their small size—are functional and produce a very potent secretion. 相似文献
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Joke Muys Bettina Blaumeiser Yves Jacquemyn Claude Bandelier Nathalie Brison Saskia Bulk Patrizia Chiarappa Winnie Courtens Anne De Leener Marjan De Rademaeker Julie Désir Anne Destrée Koenraad Devriendt Annelies Dheedene Annelies Fieuw Erik Fransen Jean-Stéphane Gatot Philip Holmgren Mauricette Jamar Sandra Janssens Kathelijn Keymolen Damien Lederer Björn Menten Marije Meuwissen Benoit Parmentier Bruno Pichon Sonia Rombout Yves Sznajer Ann Van Den Bogaert Kris Van Den Bogaert Olivier Vanakker Joris Vermeesch Katrien Janssens 《黑龙江环境通报》2018,38(13):1120-1128