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791.
Bi-directional sex change in a coral-dwelling goby 总被引:1,自引:0,他引:1
Philip L. Munday M. Julian Caley Geoffrey P. Jones 《Behavioral ecology and sociobiology》1998,43(6):371-377
Bi-directional sex change has recently been reported among obligate coral-dwelling gobies of the genus Gobiodon. However, neither the functional role of this pattern of sex change nor the frequency of sex change in either direction in
natural populations is known. We investigated the social structure and pattern of sex change of Gobiodon histrio at Lizard Island on the Great Barrier Reef. The social structure of G. histrio within coral colonies usually consisted of a single juvenile or a heterosexual adult pair. The size of adult social groups
was not constrained by coral colony size. In contrast to expectations for pair-forming species, G.␣histrio was primarily a protogynous hermaphrodite. All immature G. histrio were females and sex change from female to male occurred readily when two mature females were placed in a coral colony. In
addition, male G. histrio were able to change back to females when two mature males were placed in a coral. Sex change from female to male, however,
occurred with over twice the frequency of sex change from male to female. Where two males were placed in a coral colony, heterosexual
pairs were most frequently re-established by immigration of females from outside the treatment population. This pattern might
be predicted if sex change from male to female is more expensive than sex change from female to male for G. histrio. Where sex change is expensive, movement may be favoured over sex change, particularly where coral densities are high and
movement among corals incurs little mortality risk.
Received: 10 November 1997 / Accepted after revision: 16 May 1998 相似文献
792.
793.
Dioxin-like compounds in agricultural soils near e-waste recycling sites from Taizhou area, China: chemical and bioanalytical characterization 总被引:8,自引:0,他引:8
Shen C Chen Y Huang S Wang Z Yu C Qiao M Xu Y Setty K Zhang J Zhu Y Lin Q 《Environment international》2009,35(1):50-55
The crude recycling of electronic and electric waste (e-waste) is now creating a new set of environmental problems especially in developing countries such as China. The present study aimed to characterize the dioxin-like compounds in Taizhou area, one of the largest e-waste recycling centers in China, using both chemical analysis and in vitro bioassay. Agricultural soil samples were screened for aryl hydrocarbon receptor (AhR) activity with EROD bioassay in H4IIE cells, and the concentrations of the target AhR agonists including polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) were determined by instruments. The bioassay-derived TCDD equivalents (TEQ(bio)) and the chemical-calculated TCDD equivalents (TEQ(cal)) were then compared, and mass balance analysis was conducted to identify the contributors of the observed response. Raw soil extracts from all locations induced significant AhR activities, where the TEQ(bio) ranged from 5.3 to 210 pg/g dry weight soil (pg/g dw). The total concentrations of 17 PCDD/Fs, 36 PCBs and 16 PAHs varied from 210 to 850 pg/g dw, 11 to 100 ng/g dw, and 330 to 20,000 ng/g dw, respectively. Profile characterization of the target analytes revealed that there were similar sources originating from the crude dismantling of electric power equipments and the open burning of e-waste. There was a significant relationship between TEQ(cal) and TEQ(bio) (r=0.99, p<0.05). Based on the mass balance analysis, PCDD/Fs, PCBs and PAHs could account for the observed AhR responses in vitro elicited by soil extracts, though their respective contributions varied depending on sample location. In this study, the combination of chemical analysis and bioanalytical measurements proved valuable for screening, identifying and prioritizing the causative agents within complex environmental matrices. 相似文献
794.
南水北调中线工程对陆生植物的影响及其对策初步研究 总被引:3,自引:0,他引:3
介绍了南水北调中线工程丹江口水库库区及输水总干渠沿线所经地区的自然环境状况和植物资源特征;分析了工程所造成的淹没,占地,移民和迁建用材等方面对库区和干渠沿线地段的陆生植物和植物物种资源各方面所可能造成的损失,以及有益的影响,并针对库区和干渠沿线的植物资源保护,环境恢复和地区经济重建等问题提出对策。 相似文献
795.
796.
797.
根据粉尘层反电晕现象分析,提出在接地收尘极板上布置芒刺反电晕放电极的双极电晕静电除尘器,这种双极电晕静电除尘器能避免粉尘层的反电晕。在平均场强约3.4kV/cm时,采用粒子图像测速仪(PIV)测得电场内正、负离子风的核心区风速约2m/s。实验表明,离子风对收集微细粉尘有很好的促进作用。在常温常压下,平均场强为3.4kV/cm、气流速度在0.5~2.0m/s的范围内,对质量中位径为0.159μm、比电阻为2.4×1014Ω.cm的硅微粉的电除尘效率测定结果表明,双极荷电静电除尘器的除尘效率高于单极荷电静电除尘器。观察发现,由于接地芒刺的存在,即使对于比电阻高达2.4×1014Ω.cm的硅微粉,沉积在双极荷电静电除尘器收尘极板上的粉饼没有出现反电晕。 相似文献
798.
常温(26~30℃)下应用连续流短程硝化反硝化工艺处理模拟城市生活污水,对连续流短程硝化反硝化污泥的运行参数进行了研究.结果表明,在常温、进水NH4 -N为50 mg/L、曝气区pH为7.5~8.0、曝气量为0.3 L/min、曝气区水力停留时间为4 h的条件下,NO2- -N/(NO3- -N NO2- -N)达0.677,TN去除率为35%左右;在上述条件下,无需调节曝气区pH,选择前置反硝化区与曝气区的体积比为1:2、前置反硝化区水力停留时间为2 h、回流比为2:1时,连续流短程硝化反硝化工艺的TN去除率达88.9%,COD去除率达92.7%;pH的变化规律正确反映了系统运行状况,可作为系统运行的实时控制参数. 相似文献
799.
高压电晕与臭氧联用对不同结构染料脱色效果的比较研究 总被引:1,自引:0,他引:1
比较研究了高压电晕与臭氧联用对活性艳红X-3B(单偶氮)、活性艳蓝X-BR(蒽醌)、活性黑KN-GRRC(双偶氮)、酸性红ARL(单偶氮)、酸性蓝BRL(蒽醌)、酸性橙AGT(双偶氮)和分散蓝2BLN(蒽醌)7种染料模拟废水的脱色效果.结果显示,酸性橙AGT模拟废水的脱色速度较慢,而其他6种染料在15 min内都能完全脱色,这表明染料结构本身的差异决定了脱色效果;活性染料模拟废水的脱色效果优于酸性染料;蒽醌染料和单偶氮染料模拟废水的脱色效果明显好于双偶氮染料. 相似文献
800.