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91.
Giovanni A. P. dos Santos Sofie Derycke Verônica G. F. Genevois Luana C. B. B. Coelho Maria T. S. Correia Tom Moens 《Marine Biology》2009,156(4):629-640
Accurate prediction of the biodiversity–ecosystem functioning relationship requires adequate understanding of the interactions
among species in a community. Effects of species diversity on ecosystem functioning are usually considered more pronounced
with increasing functional dissimilarity, although species within functional groups may also perform non-identical functions
and interact with each other. Here we present results of a laboratory experimental study aimed at elucidating whether interspecific
interactions among species within a single nematode trophic group, bacterivores, (1) affect population development and community
structure, and (2) depend on food availability. We studied the population growth of Rhabditis (Pellioditis) marina, a rhabditid nematode known to favour very high food densities when in monoculture, and of Diplolaimelloides meyli and D. oschei, congeneric Monhysteridae known to perform better in monocultures at intermediate food availability. Both Diplolaimelloides species showed significantly different patterns of food-density dependence in combination culture compared to monoculture.
At very high food availability, the rhabditid nematode facilitated growth of both monhysterid species, probably as a result
of down-regulation of bacterial density. At the lowest food availabilities, the presence of even low numbers of monhysterid
nematodes lead to exclusion of the rhabditid, which at such low food availability has a very inefficient food uptake. At intermediate
food availabilities, abundances of both Diplolaimelloides species were strongly depressed in the combination culture, as a result of food depletion by the rhabditid, indirect inhibitory
interactions between the two congeneric species, or both. The complexity of the species interactions render predictions on
the outcome and functional consequences of changes in within-trophic-group diversity highly problematic. 相似文献
92.
Pedro Daleo Tomás Luppi Agustina Mendez Casariego Mauricio Escapa Pablo Ribeiro Paola Silva Oscar Iribarne 《Marine Biology》2009,156(3):269-275
Size advantage in male–male competition over mates, combined with male preference over large females, is a common feature
that can drive to size assortative mating and, eventually, sexual selection. In crabs, appendage autotomy can affect assortative
mating and opportunity for sexual selection by affecting size advantage in mating contests. In this work, we evaluate the
effect of size and appendage autotomy in generating assortative mating in the mud crab Cyrtograpsus angulatus. Field observations of guarding pairs in two different populations show a positive correlation between carapace width of
males and females in both the populations. In one of the populations, incidence of appendage autotomy was low and the variability
in the size of reproductive males was lower than the variability in the size of randomly collected males (i.e. only larger
males were successful in getting a female), whereas there was no differences in the other population (i.e. most male sizes
were successful) where the incidence of appendage autotomy was very high, indicating that the importance of size is higher
when the incidence of autotomy is low. In this context, experiments (in both populations) show that, in contests for a female,
larger males outcompete smaller ones only when they had intact appendages. When males had missing chelipeds, winning or loosing
against smaller males was random. This may lead to a decrease in the importance of male size in populations with high incidence
of cheliped autotomy, affecting assortative mating and opportunity for selection and, thus, affecting selective pressures. 相似文献
93.
Calculations of large-scale displacement distances were made to evaluate the combined effect of small-scale movement pattern of a Collembola, Protaphorura armata. The effect of presence of food and conspecific density on turning angle, step length and activity/motility was investigated. Calculations of net square displacement were made both by assuming correlated random walk (CRW) and by resampling data to account for correlation structures in movement patterns that violate the assumptions of CRW. 相似文献
94.
Yubo Cao Zhaohai Bai Tom Misselbrook Xuan Wang 《Journal of the Air & Waste Management Association (1995)》2021,71(1):23-33
ABSTRACT Pig production systems in China are shifting from small to industrial scale. Significant variation in housing ammonia (NH3) emissions can exist due to differences in diet, housing design, and management practices. However, there is a knowledge gap regarding the impacts of farm-scale in China, which may be critical in identifying hotspots and mitigation targets. Here, continuous in-situ NH3 concentration measurements were made at pig farms of different scales for sows and fattening pigs over periods of 3–6 days during two different seasons (summer vs. winter). For the sow farms, NH3 emission rates were greater at the small farm (summer: 0.52 g pig?1 hr?1; winter: 0.21 g pig?1 hr?1) than at the large farm (summer: 0.34 g pig?1 hr?1; winter: 0.12 g pig?1 hr?1). For the fattening pig farms, NH3 emission rates were greater at the large farm (summer: 0.22 g pig?1 hr?1; winter: 0.16 g pig?1 hr?1) than at the small farm (summer: 0.19 g pig?1 hr?1; winter: 0.07 g pig?1 hr?1). Regardless of farm scale, the NH3 emission rates measured in summer were greater than those in winter; the NH3 emission rates were greater in the daytime than at the nighttime; a positive relationship (R2 = 0.06–0.68) was established between temperature and NH3 emission rate, whereas a negative relationship (R2 = 0.10–0.47) was found between relative humidity and NH3 emission rate. The effect of farm-scale on indoor NH3 concentration could mostly be explained by the differences in ventilation rates between farms. The diurnal variation in NH3 concentration could be partly explained by ventilation rate (R2 = 0.48–0.78) in the small traditional farms and by emission rate (R2 = 0.26–0.85) in the large industrial farms, except for the large fattening pig farm in summer. Overall, mitigation of NH3 emissions from sow farms should be a top priority in the North China Plain. Implications: The present study firstly examined the farm-scale effect of ammonia emissions in the North China Plain. Of all farms, the sow farm was identified as the greatest source of ammonia emission. Regardless of farm scale, ammonia emission rates were observed to be higher in summer. Ammonia concentrations were mostly higher in the large industrial farms partly due to lower ventilation rates than in the small traditional farms. 相似文献
95.
Effects of heavy metals and nitroaromatic compounds on horseradish glutathione S-transferase and peroxidase 总被引:7,自引:0,他引:7
Glutathione S-transferase (GST) and peroxidase (POX) activities have a direct relation to the effect of stress on plant metabolism. Changes in the activities of the enzymes were therefore studied. Horseradish hairy roots were treated by selected bivalent ions of heavy metals (HMs) and nitroaromatic compounds (NACs). We have shown differences in GST activity when assayed with substrates 1-chloro-2,4-dinitrobenzene (CDNB) and 1,2-dichloro-4-nitrobenzene (DCNB). The conjugation of DCNB catalysed by GST was inhibited in all roots treated with HMs as compared to non-treated roots, whereas NACs caused induction of the activity in dependence on the exposition time and concentration of compounds. The conjugation of CDNB by GST was not affected to the same extent. The increase of GST activity was determined in cultures treated by nickel (0.1 mM) and diaminonitrotoluenes (DANTs, 0.1 mM) for 6 h, whereas the roots treated by 2,4,6-trinitrotoluene (TNT), 4-amino-2,6-dinitrotoluene (ADNT) and dinitrotoluene (DNT, 1.0 mM) needed 27 h treatment to induce the activity. The POX activity of cultures treated by HMs was inhibited to 17-35% in comparison to non-treated cultures. The POX activity of roots treated by TNT (0.1 and 1.0 mM) for 6 and 27 h and by ADNT (0.1 and 1.0 mM) for 6 h was inhibited. A partial increase of POX activity was measured in roots treated by all NACs for 27 h. The content of oxidized glutathione (GSSG) and reduced glutathione (GSH) in the roots differed significantly. It was followed as a symptom of the stress reaction of the plant metabolism to the effect of NACs and HMs. 相似文献
96.
Global pilot study for persistent organic pollutants (POPs) using PUF disk passive air samplers 总被引:2,自引:0,他引:2
Harner T Pozo K Gouin T Macdonald AM Hung H Cainey J Peters A 《Environmental pollution (Barking, Essex : 1987)》2006,144(2):445-452
Polyurethane foam (PUF) disks were deployed at global background sites, to test logistical issues associated with a global monitoring network for persistent organic pollutants (POPs). alpha-HCH, exhibited relatively high and uniform concentrations (17-150 pg/m3) at temperate and arctic sites with elevated concentrations associated with trans-Pacific inflow. Concentrations were much lower (<5 pg/m3) in Bermuda, Chile and Cape Grim. Concentrations for gamma-HCH, the main component of lindane, were spatially similar to the alpha-HCH pattern but lower in magnitude (typically, <10 pg/m3). Chlordane concentrations (sum of cis-chlordane, trans-chlordane and trans-nonachlor) were also low (<10 pg/m3). Dieldrin concentrations were in the range 2-25 pg/m3 at most sites but elevated in Bermuda. Back trajectories suggest that advection from Africa and the US may contribute. Endosulfan, a popular current-use pesticide, exhibited highest concentrations ranging from tens to hundreds of pg/m3. There was good agreement between duplicate samplers at each site and PUF disk-derived air concentrations agreed with high volume data. Few logistical/analytical problems were encountered in this pilot study. 相似文献
97.
98.
99.
Maroušek Josef Maroušková Anna Zoubek Tomáš Bartoš Petr 《Environment, Development and Sustainability》2022,24(4):4835-4844
Environment, Development and Sustainability - The most common drinking water clarification technology worldwide is based on precipitation using the floccules of iron(III) oxide-hydroxide FeO(OH).... 相似文献
100.
Ana Cristina Mugetti Alberto Tomás Calcagno Carlos Alberto Brieva María Silvia Glangiobbe Andrea Pagani Silvia G.Gonzalez 《Ambio-人类环境杂志》2004,33(1):67-75
本文描述了南美大陆南部陆地和东南沿海地区环境特性及水生栖息地和群落的现状(GIWA巴塔哥尼亚大陆架亚区),结果来自一项GIWA项目框架任务所完成的一份全面评估,绝大部分依据的是公开发表的数据.分析主要集中在跨边界水资源目前的情况和人类活动带来的影响.内陆水体的栖息地和群落变化主要是由为发电和其他用途而建的水坝和水库引起的.从活水环境到净水环境影响了生境,造成了生物群落的改变.在拉普拉塔(La Plata)河流域,外来入侵物种使本地物种消失.过度捕捞和污染影响了生物多样性,造成了海洋栖息地质量下降.本篇文章讨论了相关的原因,讨论了布宜诺斯艾利斯省和渔业资源由两国共享的阿根廷-乌拉圭公共渔业区对沿海生态环境的政策选择. 相似文献