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Abstract The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) was created to prevent species becoming threatened through international trade. It generally prohibits international commercial trade in seriously threatened species but permits trade in a regulated manner in species vulnerable to exploitation but not yet at risk of extinction. CITES covers comparatively few marine taxa, reflecting the fact that most marine species have much greater ranges and fecundity than terrestrial species and so are more resilient to exploitation. Exceptions are to be found in the higher vertebrates. Several marine mammals may have benefited from CITES controls, although their popular appeal, commercial importance, and extreme vulnerability have meant that other treaties and conservation activities have been adopted to control their exploitation. Marine turtles Cheloniidae and the estuarine crocodile (Crocodylus porosus) certainly have benefited from CITES controls. Many commercially important fishes and invertebrates are covered by international and regional fishery agreements; a few, with life histories making them particularly vulnerable to exploitation, are subject to CITES controls. The structure of CITES limits its utility as a conservation tool for marine species, but where other mechanisms fail or are absent, it plays a useful role, and it is particularly valuable as an international trade monitoring mechanism. 相似文献
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Ferenc Jordn 《Journal of Marine Systems》2001,27(4):59
Community-level processes may shape food web structure. In this paper, a graph theoretical study of the weighted trophic flow network of the Chesapeake Bay ecosystem shows how important are positions in the energy (carbon) transport system. The positional importance of components is compared to the quantity of energy flowing through them. We suggest that the congruence between important network positions and large flows refers to the larger role of trophic interactions in community control. A seasonal dynamical analysis of the network has led us to the conclusion that winter is the season when the importance of predation is the highest. 相似文献
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目的观察黄芪总皂苷对瘦素诱导的肝星状细胞(HSC)增殖及组织抑制基质金属蛋白酶-1(TIMP-1)分泌的影响。方法培养HSC,分为溶媒组、溶媒瘦素组和黄芪总皂苷组。磺酰罗丹明B法检测HSC增殖,利用2,7-二氯二氢荧光素二乙酯作为探针检测HSC中的活性氧水平,酶联免疫吸附实验测定HSC培养液中TIMP-1含量。结果黄芪总皂苷50、100、200μg/mL与溶媒瘦素组相比,明显抑制瘦素诱导的HSC增殖(P<0.01),抑制率分别达29.1%、66.7%和86.1%,同时能够抑制瘦素诱导HSC的活性氧产生(P<0.05)以及TIMP-1的分泌(P<0.05)。结论黄芪总皂苷可能通过下调瘦素诱导的氧化应激水平,从而抑制HSC增殖以及TIMP-1的分泌。 相似文献
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