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21.
Two wastewater natural reclamation systems (WWNRS) have been compared regarding their efficiencies on faecal bacteria removal and the persistence of enteric pathogens. These WWNRS are constituted of a combination of anaerobic treatment, small sub-surface flow constructed wetland refilled of volcanic ashes and a final pond as water reservoir. Faecal coliforms, enterococci, Escherichia coli, Clostridium perfringens, somatic coliphages, Salmonella sp., Campylobacter sp., Cryptosporidium sp., Giardia sp. and helminth eggs were analyzed in constructed wetlands inlet and outlet and storage pond effluent. Low numbers of protozoan positive samples (4.54% in Albergue de Bolico for both protozoa, and 19.05% in Carrizal Alto for Giardia sp.) and absence of helminth eggs were found. Both systems demonstrated efficient reduction of faecal contamination indicators in the wastewaters (removal rates values of 2 log10). The natural systems for wastewater treatment used to be efficient in Salmonella abatement, this fact was confirmed in the reported systems, since enterobacteriaceae were found in only one of the effluents. Campylobacter species associated with the access of animals to storage ponds were detected in the reclaimed water.  相似文献   
22.
There is a general perception that dust accumulation on plant surfaces causes negative impacts to plants. Consequently, it is common for environmental regulatory agencies to apply vegetation monitoring requirements to oil, gas and mining developments. We use two independent, medium‐term monitoring studies in semi‐arid Australia to examine this relationship at two scales: plant health and survivorship of a threatened subspecies (Tetratheca paynterae paynterae: Elaeocarpaceae) at Windarling Range between 2003 and 2014; and changes in plant health and floristic composition on Barrow Island between 2009 and 2014. Accumulation of dust decreased rapidly with distance from source. At Windarling Range, even at the site with the highest dust load, there was no significant impact on Tetratheca paynterae paynterae compared with the less dusty sites for 10 years. Similarly, there was no significant effect between distance from the source of dust and floristic composition on Barrow Island for 5 years. The probability of plants transitioning to a lower health condition between one year and the next did not appear to be related to dust load. This is further supported by comparing the same site before and after paving the road (removal of dust source), which showed no clear trends. Trends in plant health are likely to be driven more by the variability of cumulative rainfall in the preceding 5 months than dust load. The observed temporal variation in the mean dust load may also be related to variation in rainfall. In conclusion, in these case studies from semi‐arid Australia, we find no evidence to support the perception that, under the observed climatic condition and dust deposition rates up to 20 or 77 g m?2 per month at Windarling Range and Barrow Island, respectively, dust accumulation on plants causes negative impacts.  相似文献   
23.
Feral cat Felis catus predation on seabirds has been well documented; however, details regarding shifts in feral cat diet in relation to seabird availability, seabird predation rate and impact on seabird population dynamics are scarce. Here, we present data documenting a seasonal shift in feral cat diet at Juan de Nova Island, Mozambique Channel. We also quantify sooty tern Sterna fuscata predation by feral cats and examine the impact on sooty terns over both the short term (by removing individual cats from sub-colonies) and over the longer term by highlighting their influence on population growth rate ( λ ) using a deterministic matrix model. Cat diet shifted dramatically from insects, rats and mice outside the tern breeding season to primarily terns when terns were breeding. The predation rate of sooty terns at Juan de Nova was estimated at 5.94 terns cat−1 day−1, with a proportion of these (22%) being killed without being consumed ('surplus kills'). When only one cat was removed from each sub-colony, tern predation declined tenfold in the short term. From our matrix model, the annual growth rate for sooty terns was 1.01 in the absence of cat predation. It remained above one until a predation impact equivalent to approximately three times the estimated cat density (12.04 per km2) was incorporated. Our results demonstrate that cats preferentially predate and have an impact on breeding sooty terns at Juan de Nova, and that an increase in cat density could lead to negative effects on population growth, despite the large breeding tern population.  相似文献   
24.
Svenning JC  Fabbro T  Wright SJ 《Oecologia》2008,155(1):143-150
Competition is believed to be a central force limiting local diversity and controlling the structure of plant communities. However, it has been proposed that the stressed understory environment limits total understory plant density to such low levels that competitive exclusion cannot be an important factor limiting the local diversity of understory plants. To evaluate the importance of inter-seedling competition, we performed a seedling competition experiment with five shade-tolerant species in a tropical moist forest in Panama. Three-month-old seedlings were transplanted into the forest singly or with their roots intertwined with a single conspecific or heterospecific seedling in all pairwise species combinations. If competition is important, performance (survival, stem height, and number of leaves after one and six years) would be expected to be lowest with a conspecific neighbor and greatest without a neighbor. The experiment was replicated in five 0.24-m2 plots at each of 20 sites in tall secondary forest. To test whether seedling performance differed among treatments we fitted linear mixed models (LMM) and generalized linear mixed models (GLMM), treating species identity and microsite (site and plot) as random effects. The five shade-tolerant study species all experienced good establishment with relatively high survival and growth rates. The neighbor treatment consistently affected seedling performance, but the effect was always very small, both in absolute terms and relative to the much stronger species and microsite effects. Seedlings with a conspecific neighbor consistently performed worse than seedlings with a heterospecific neighbor, but having no neighbor generally did not cause superior performance relative to the other treatments. We conclude that direct competitive interactions are relatively unimportant among understory plants in humid tropical forests.  相似文献   
25.
中国大陆青冈分布区东缘大金山岛种群种子形态变异   总被引:3,自引:0,他引:3  
陈艳  沈浪  应向阳 《广西植物》2007,27(4):555-559
在大陆青冈分布区东缘的大金山岛种群中按不同坡向取样,旨在揭示相对均一条件下青冈种子的形态变异及变异的来源,以从不同侧面研究环境对形态变异的作用。大金山岛种群青冈种子的长度、直径和重量分别为1.557±0.128cm、1.175±0.112cm、1.321±0.310g,处于青冈种子正常分布范围内。单颗种子的长度、直径符合正态分布,而重量则明显偏离正态分布。不同坡向青冈种子间差异很小,表明微地形的影响较小;种群变异的来源株内和株间约各占一半,说明种子表型具有一定的可塑性,主要由于种子处于植株不同部位的缘故。  相似文献   
26.
In Central Kalimantan, Indonesia, the water of lakes and rivers showed high dissolved organic carbon (DOC) concentration, 5-50mgC/l. There was a clear relationship between DOC concentration and pH. DOC also contributed to low water transparency in the studied lakes. Water colors measured by spectrophotometer showed a strong relationship with DOC concentration, indicating high applicability of water color measurement for estimation of DOC. The development of a simple but quick estimation of DOC will contribute to understanding the seasonal dynamics of DOC, which might regulate both abiotic and biotic conditions in aquatic ecosystems in this area.  相似文献   
27.
为探究滨豇豆(Vignamarina)的生态生物学特性及其对热带珊瑚岛的适应性,对西沙群岛野生滨豇豆的叶片形态解剖结构、生理特征和营养成分进行了分析。结果表明,滨豇豆具有叶片厚、比叶面积小、栅栏组织发达、气孔密度大、气孔面积指数大等形态特征,对减少蒸腾、保持水分起到重要作用。滨豇豆叶片的SOD活性和脯氨酸(Pro)含量高,丙二醛(MDA)含量低,表明抗氧化能力较强;滨豇豆叶片养分含量适中但其生境土壤养分含量很低,说明其对养分有着良好的吸收利用能力,利于适应贫瘠的环境。因此,滨豇豆具有能够较好地适应珊瑚岛礁高温、干旱、贫瘠生境的形态解剖结构和生理特征,加之其具有良好的固氮和养分利用能力,可作为热带珊瑚岛植被恢复的工具种。  相似文献   
28.
A new zoarcid fish, Lycodes mcallisteri, is described on the basis of nine specimens (230–375 mm SL) from eastern Arctic Canada, Nunavut (Hudson Strait, 298 m; Cumberland Sound and Baffin Bay, 579 m). It resembles about 15 other Lycodes spp. in having a long tail and a "ventromediolateral" type of lateral line. It is distinguished from Arctic members of this group (Lycodes marisalbi, L. palearis, and L. sagittarius) by the high number of pectoral fin rays (22–23), short pelvic fins, low submental crests, and coloration (6–10 light patches dorsally). It resembles two Pacific species (L. macrochir and L. soldatovi) by the high number of pectoral fin rays, but differs by coloration, meristics, and shape of the pectoral fin. Received: April 13, 2000 / Revised: September 7, 2000 / Accepted: January 11, 2001  相似文献   
29.
广东内伶仃岛猕猴食性及食源植物分析   总被引:8,自引:0,他引:8  
论文对内伶仃岛猕猴(Macaca mulatta)的植物食性进行了全面调查,并测定了食源植物适食部分的比重。研究结果表明:(1)猕猴食源植物约200种,以叶食性、果食性最为丰富;(2)猕猴的活动区域以阔叶林、灌木林等植被类型为主;(3)食源植物以热带亚热带成分为主,与栖息地植被组成特征相适应;(4)内伶仃岛猕猴种群发展的容纳量最适为820~1640只(平均1230只),而以743~1485只(平均1114只)最为合适,其总食量约相当于适食性优质植物资源总蕴藏量的10%~20%。  相似文献   
30.
胡璇  徐瑞晶  漆良华  彭超  丁霞  程昌锦  郭雯  张建 《生态学报》2019,39(22):8539-8546
以海南岛甘什岭热带低地雨林白藤(Calamus tetradactylus)、大白藤(C.faberii)、华南省藤(C.rhabdocladus)、黄藤(Daemonorops margaritae)和小钩叶藤(Plectocomia microstachys)5种棕榈藤种群为研究对象,采用点格局分析方法对棕榈藤种内和种间空间分布格局及相互关系进行分析。结果表明:(1)海南岛甘什岭热带低地雨林棕榈藤种群的空间格局与空间尺度有着密切的关系,在小尺度上,5种棕榈藤种群都更倾向于聚集分布,随着尺度的增长,各棕榈藤种群主要趋向于随机分布,形成不同的空间分布格局。(2)各藤种间的空间关联情况在整体尺度上表现出明显负关联的是白藤和黄藤、白藤和大白藤,这可能是因为它们对生存空间及养分的需求相同或相似,存在明显的竞争关系。(3)华南省藤和大白藤在整体尺度上表现出明显正关联,这可能是由于它们在生长过程中相互庇护,用于抵御动物捕食和热带雨林内多变的外部环境。(4)黄藤和小钩叶藤以及白藤和小钩叶藤呈现出明显不相关,这说明它们对环境和生存空间的依赖没有冲突性,能做到和平共存。  相似文献   
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