非离子型表面活性剂AE对大Biao损伤程度的酶学诊断

以超氧化物歧化酶（SOD）,过氧化氢酶（CAT）和过氧化物酶（POD）的比活力变化作为观测指标,进行了脂肪醇聚氧乙烯醚（AE）对大Biao(Pistia stratiotesL.)损伤程度的酶学诊断,结果表明：在17℃下,ρ（AE）0.1mg/L的AE对大Biao的伤害程度极微,ρ（AE）为1．0,10．0mg/L时,大Biao受到较大的伤害,但能逐渐恢复正常生理活动,ρ（AE）为20．0,50．0mg/L时,由于伤害程度大,超出了酶的修复能力,组织逐渐坏死,同时推测,在AE污染下,大Biao的POD是起保护作用的主导酶。ρ     

表面活性剂AE对黄鳝保护酶SOD、CAT和GSH-PX活性的影响

以肝脏组织保护酶λ(SOD)、λ(CAT)和λ(GSH PX)为指标 ,研究了表面活性剂AE(脂肪醇聚氧乙烯醚 )污染对黄鳝 (Monopterusalbus)的损伤作用 .结果显示 :ρ(AE) 1.5mg/L处理液对黄鳝的损伤较小 ;随着 ρ(AE)升高 ,损伤程度加剧 .ρ(AE) >4 .5mg/L的处理液对黄鳝损伤较大 ,保护酶λ(SOD)、λ(CAT)在处理 96h后被抑制 ,λ(GSH PX)升高 .发现环境中AE的残留量对黄鳝种群有影响 .也证实了λ(SOD)、λ(CAT)和λ(GSH PX)变化可以反映黄鳝的伤害程度 .表 3参 14     

非离子型表面活性剂AE对大薸损伤程度的酶学诊断

以超氧化物歧化酶 (SOD)、过氧化氢酶 (CAT)和过氧化物酶 (POD)的比活力变化作为观测指标 ,进行了脂肪醇聚氧乙烯醚 (AE)对大薸 (PistiastratiotesL .)损伤程度的酶学诊断 .结果表明 :在 17℃下 ,ρ(AE) 0 .1mg L的AE对大薸的伤害程度极微 ;ρ(AE)为 1.0、10 .0mg L时 ,大薸受到较大的伤害 ,但能逐渐恢复正常生理活动 ;ρ(AE)为 2 0 .0、5 0 .0mg L时 ,由于伤害程度大 ,超出了酶的修复能力 ,组织逐渐坏死 .同时推测 :在AE污染下 ,大薸的POD是起保护作用的主导酶 .图 3表 1参 12     

4,4'-二氨基二苯基甲烷对浮萍(Lemna minor L.)毒性作用

以浮萍(Lemna minor L.)为受试生物,通过研究不同浓度(0、0.6、1.8、5.4、16.2和48.6 mg·L-1)的4,4'-二氨基二苯基甲烷(4,4'-methylenedianiline,MDA)对浮萍生长、叶绿素含量、PSⅡ最大光化学效应(Fv/Fm)、质膜透性及超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性的影响,初步探讨MDA对水生植物浮萍的毒性作用.实验结果表明,在7d暴露时间下,MDA对浮萍叶片数、叶片数生长率、叶片干质量和叶面积都有显著的抑制作用,且抑制程度与MDA的浓度呈正相关.其对浮萍叶片数生长抑制的7d半数效应浓度(7 d-ECs0)为26.7 mg·L-1,95％置信限为22.3 ～ 32.1 mg·L-1;对浮萍叶片数产量抑制的7 d-EC50为0.62 mg-L-1,95％置信限为0.53～0.74 mg-L-1;对浮萍总叶面积及干质量产量抑制的7 d-EC50＜0.6 mg·L-1.MDA处理导致浮萍总叶绿素含量和Fv/Fm下降,而浮萍质膜透性显著增加.低浓度MDA对浮萍SOD、POD和CAT酶活性无显著影响,但随着MDA浓度的升高SOD、POD和CAT酶活性显著升高,当MDA浓度达到48.6 mg· L-1时,抑制POD和CAT酶活性.以上结果表明,MDA能够直接损伤质膜,干扰叶绿体功能并抑制光合活性,而氧化损伤是质膜损伤引起的继发性应激,继而引起膜脂质过氧化,加剧质膜损伤,从而进一步抑制浮萍的生长.     

硝酸铊对浮萍(Lemna gibba L.)的生长抑制及其氧自由基损伤作用

为了探讨硝酸铊(Tl(I)-nitrate)对浮萍(Lemna gibba L.)的生长抑制作用及其可能的氧化损伤机制,设置了Tl(I)-nitrate的8个处理组(0.005、0.01、0.02、0.04、0.08、0.1、0.5和1.0 mg·L-1)和对照组(0.0 mg·L-1),进行96 h急性毒性实验,测定96 h内超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性及丙二醛含量。结果表明:96 h暴露时间下,浮萍生长受抑制程度与Tl(I)浓度之间呈正相关,Tl(I)-nitrate对浮萍的96 h EC50为0.076 mg·L-1,NOEC为0.01 mg·L-1。CAT活性随着Tl(I)-nitrate浓度升高逐渐降低,在0.5和1 mg·L-1时,有极显著差异(p0.01)产生,SOD活性在0.1 mg·L-1时显著升高(46%),POD活性和MDA含量在Tl(I)浓度0.5 mg·L-1时明显上升。当Tl(I)-nitrate胁迫超出浮萍抗氧化酶系统清除活性氧的能力时,活性氧积累导致浮萍受到不可逆转的氧化损伤。Tl(I)-nitrate对浮萍生长产生明显的抑制作用     

三苯基锡对青萍生长及酶活性的影响

以青萍(Lemna mino)为实验生物,通过研究不同浓度(0、0.04、0.08、0.12、0.16、0.20mg·L-1)的三苯基锡(TPT)对青萍生长发育及过氧化氢酶(CAT)和过氧化物酶(POD)活性的影响,初步探讨了TPT对水生浮萍植物的毒性作用,以期为及时发现并排除TPT污染提供理论和直观依据.实验结果表明:培养4d后,TPT对青萍叶片生长量的半数抑制浓度(IC50)为0.10mg·L-1;CAT、POD活性随TPT处理浓度的升高显著升高(各暴露组与对照组均差异显著,p<0.05).结果显示,TPT对青萍具有明显的毒性作用,CAT和POD活性的变化可作为反映TPT污染胁迫的敏感指标.     

盐酸小檗碱对小鼠脾细胞的DNA损伤和氧化性损伤研究

为了探讨盐酸小檗碱对小鼠的DNA损伤和氧化性损伤。随机选取30只小鼠分成对照组以及7.5,15,30,60与120 mg?kg^-1实验组,处理后,应用小鼠脾细胞进行彗星实验与抗氧化酶实验。测定DNA损伤情况以及超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、过氧化物酶（POD）活性以及丙二醛（MDA）含量变化。对盐酸小檗碱的DNA损伤与氧化性损伤作用进行比较研究。研究结果表明：彗星实验中,随着盐酸小檗碱浓度的增加,尾部DNA含量、尾长与尾矩均增加,与阴性对照组相比差异有统计学意义（p<0.05或p<0.01）,且呈剂量-效应关系;超氧化物歧化酶(SOD)与过氧化氢酶(CAT)活性随盐酸小檗碱剂量增加逐渐降低,丙二醛(MDA)含量明显下降,过氧化物酶(POD)活性在7.5 mg?kg^-1时上升,而后逐渐下降。在60 mg?kg^-1和120 mg?kg^-1时,有极显著性差异（p<0.01）产生。由此可见,盐酸小檗碱对小鼠脾细胞有一定的损伤作用,能够引起小鼠脾细胞的DNA损伤和氧化性损伤。     

磷酸缓冲液预处理对高温胁迫下油菜叶片膜脂过氧化及体内保护系统的影响

高温胁迫下,油菜叶片细胞膜相对透性、丙二醛（MDA）含量和过氧化物酶（POD）活性增加;抗坏血酸（ASA）、谷胱甘肽（GSH）、可溶性蛋白质总量及热稳定性蛋白质所占比例与超氧化物歧化酶（SOD）和过氧化氢酶（CAT）活性下降;酸缓冲液预处理可维持较高的保护酶活性、抗氧化物质含量和较低的膜脂过氧化水平．     

土壤汞污染对油菜的氧化胁迫效应

为了明确土壤汞污染的植物毒性效应,利用盆栽模拟试验研究了汞污染土壤对油菜的氧化损伤.结果表明,低浓度的汞污染轻微促进油菜的生长,汞浓度超过1.0 mg·kg-1就显著抑制植物生长,引起叶片面积变小、失绿变黄甚至枯萎等生理现象.随着汞浓度的增加,丙二醛(MDA)含量增加,当汞的浓度增加到8.0 mg·kg-1时,MDA的含量是对照组的4.17倍.随着汞浓度的增加,超氧化物歧化酶(SOD)活性升高,过氧化物酶(POD),过氧化氢酶(CAT)活性先升高后下降,其中SOD和POD在8.0 mg·kg-1汞处理下,活性达到最大,CAT在0.5 mg·kg-1汞处理下活性最大.土壤汞含量为超过1.0 mg·kg-1时,油菜可食部分汞浓度大于食品安全国家标准《食品中污染物限量》(GB 2762—2012)的规定.油菜吸收的汞主要累积在根部,因此在利用此类植物进行土壤修复时,需要清除植物的地下部,才能实现植物修复的目的.     

镧、锌及其交互作用对浮萍活性氧清除系统的影响

以浮萍(Lemnaminor)为材料,研究La、Zn及其交互作用对体内活性氧清除系统的影响,单独施加20mg·L-1的La或Zn对浮萍都有明显的伤害作用,且Zn的毒性远大于La。La、Zn复合处理不同程度地减弱各自的毒性,表现为植株叶绿素含量、蛋白质含量及过氧化氢酶(CAT)活性下降减缓;谷胱甘肽(GSH)、抗坏血酸(AsA)含量提高;超氧化物歧化酶(SOD)活性增强;过氧化物酶(POD)活性降低。各处理对浮萍的毒性由大到小的顺序依次为:Zn、La、Zn+La。     

Rapid,recurring, structured survey versus bioblitz for generating biodiversity data and analysis with a multispecies abundance model

A bioblitz inexpensively and quickly generates biodiversity data, but bioblitzes are often conducted with haphazard, unreplicated sampling. Results tend to be taxonomically, geographically, or temporally biased, lack metadata, and consist of lists of observed taxa that do not enable further analyses or correction for imperfect detection. A rapid, recurring, structured survey (RRSS) uses a structured sampling design and temporal and spatial replication to survey randomly selected sites on a conservation property. We participated in a loosely structured bioblitz and a subsequent RRSS at Big Canoe Creek Nature Preserve in Springville (St. Clair County), Alabama (USA) to compare observed richness derived from the 2 survey approaches. The RRSS data structure enabled us to fit models that accounted for imperfect detection to estimate abundances, occupancy probabilities, and habitat associations. The loosely structured bioblitz data could not be used in such models. We present a new integrated multispecies abundance model that we applied to avian RRSS data. Our model extension enables estimation for the community, employs data augmentation to estimate the number of undetected species, and incorporates covariates. The RRSS generated a more comprehensive and less biased list of observed taxonomic richness than the loosely structured bioblitz (e.g., 73 vs. 45 bird species and 104 vs. 63 insect families from the RRSS vs. loosely structured bioblitz, respectively). Models fit to the RRSS data identified seasonal patterns in avian community composition and allowed for estimation of habitat–occupancy relationships for insect taxa. The RRSS protocol has potential for broad transferability as a standardized, quick, and inexpensive way to inventory biodiversity and estimate ecological parameters while providing an outreach opportunity.     

Compliance with and ecosystem function of biodiversity offsets in North American and European freshwaters

Land-use change via human development is a major driver of biodiversity loss. To reduce these impacts, billions of dollars are spent on biodiversity offsets. However, studies evaluating offset project effectiveness that examine components such as the overall compliance and function of projects remain rare. We reviewed 577 offsetting projects in freshwater ecosystems that included the metrics project size, type of aquatic system (e.g., wetland and creek), offsetting measure (e.g., enhancement, restoration, and creation), and an assessment of the projects’ compliance and functional success. Project information was obtained from scientific and government databases and gray literature. Despite considerable investment in offsetting projects, crucial problems persisted. Although compliance and function were related to each other, a high level of compliance did not guarantee a high degree of function. However, large projects relative to area had better function than small projects. Function improved when projects targeted productivity or specific ecosystem features and when multiple complementary management targets were in place. Restorative measures were more likely to achieve targets than creating entirely new ecosystems. Altogether the relationships we found highlight specific ecological processes that may help improve offsetting outcomes.     

A palaeo-hydrogeological model for arsenic contamination in southern and south-east Asia

An argument is presented in which areas of natural arsenic contamination of modern groundwaters throughout Asia have a common origin. Arsenic originally accumulated in oceanic ferro-manganoan sediments of the eastern Palaeo-Tethys. This was further concentrated through oceanic crustal extinction in what later became the south-east Chinese accreted mineralised terrain. Proto-Himalayan uplift of this area created the palaeo-drainage systems of the Ganges – Brahmaputra, Irrawaddy, Mekong, and Red Rivers, with consequent headwater erosion of arsenic-rich sediments. Their downstream deposition as immature and easily redistributed Neogene sandstones, silts, and iron-rich clays has created secondary and tertiary reservoirs of adsorbed and authigenic arsenic, from which the current arsenic-rich groundwaters have evolved. Considering river basins within the above palaeo-hydrogeological framework provides a basis for assessing the risk of arsenic in groundwater basins of south and south-eastern Asia.     

Cost‐effective conservation of an endangered frog under uncertainty

How should managers choose among conservation options when resources are scarce and there is uncertainty regarding the effectiveness of actions? Well‐developed tools exist for prioritizing areas for one‐time and binary actions (e.g., protect vs. not protect), but methods for prioritizing incremental or ongoing actions (such as habitat creation and maintenance) remain uncommon. We devised an approach that combines metapopulation viability and cost‐effectiveness analyses to select among alternative conservation actions while accounting for uncertainty. In our study, cost‐effectiveness is the ratio between the benefit of an action and its economic cost, where benefit is the change in metapopulation viability. We applied the approach to the case of the endangered growling grass frog (Litoria raniformis), which is threatened by urban development. We extended a Bayesian model to predict metapopulation viability under 9 urbanization and management scenarios and incorporated the full probability distribution of possible outcomes for each scenario into the cost‐effectiveness analysis. This allowed us to discern between cost‐effective alternatives that were robust to uncertainty and those with a relatively high risk of failure. We found a relatively high risk of extinction following urbanization if the only action was reservation of core habitat; habitat creation actions performed better than enhancement actions; and cost‐effectiveness ranking changed depending on the consideration of uncertainty. Our results suggest that creation and maintenance of wetlands dedicated to L. raniformis is the only cost‐effective action likely to result in a sufficiently low risk of extinction. To our knowledge we are the first study to use Bayesian metapopulation viability analysis to explicitly incorporate parametric and demographic uncertainty into a cost‐effective evaluation of conservation actions. The approach offers guidance to decision makers aiming to achieve cost‐effective conservation under uncertainty.     

Threats to intact tropical peatlands and opportunities for their conservation

Large, intact areas of tropical peatland are highly threatened at a global scale by the expansion of commercial agriculture and other forms of economic development. Conserving peatlands on a landscape scale, with their hydrology intact, is of international conservation importance to preserve their distinctive biodiversity and ecosystem services and maintain their resilience to future environmental change. We explored threats to and opportunities for conserving remaining intact tropical peatlands; thus, we excluded peatlands of Indonesia and Malaysia, where extensive deforestation, drainage, and conversion to plantations means conservation in this region can protect only small fragments of the original ecosystem. We focused on a case study, the Pastaza‐Marañón Foreland Basin (PMFB) in Peru, which is among the largest known intact tropical peatland landscapes in the world and is representative of peatland vulnerability. Maintenance of the hydrological conditions critical for carbon storage and ecosystem function of peatlands is, in the PMFB, primarily threatened by expansion of commercial agriculture linked to new transport infrastructure that is facilitating access to remote areas. There remain opportunities in the PMFB and elsewhere to develop alternative, more sustainable land‐use practices. Although some of the peatlands in the PMFB fall within existing legally protected areas, this protection does not include the most carbon‐dense (domed pole forest) areas. New carbon‐based conservation instruments (e.g., REDD+, Green Climate Fund), developing markets for sustainable peatland products, transferring land title to local communities, and expanding protected areas offer pathways to increased protection for intact tropical peatlands in Amazonia and elsewhere, such as those in New Guinea and Central Africa which remain, for the moment, broadly beyond the frontier of commercial development.     

Parasitic wasps orient to green leaf volatiles

Summary Undamaged plants emit low levels of green leaf volatiles (GLVs), while caterpillar-damaged and artificially damaged plants emit relatively higher levels of certain GLVs. Female braconid parasitoids,Microplitis croceipes, oriented to both damaged plants and to individual GLVs in no-choice tests in a wind tunnel, but seldom oriented to undamaged plants. Female ichneumonid parasitoids,Netelia heroica, also oriented to individual GLVs in a wind tunnel. Males of both wasp species failed to orient to the GLVs. These data show that leaf-feeding caterpillars can cause the release of GLVs, and that parasitic wasps can respond to these odors by flying upwind (chemoanemotactic response), which brings the wasps to their caterpillar hosts. This supports the hypothesis that plants communicate with members of the third trophic level,i.e., plants under herbivore attack emit chemical signals that guide natural enemies of herbivores to sites of plant damage. In this interaction, the GLVs serve as tritrophic plant-to-parasitoid synomones. That parasitoids from two different wasp families oriented to GLVs suggests that the response may be widespread among the Hymenoptera.Mention of a commercial or proprietary product does not constitute an endorsement by the U.S. Department of Agriculture     

Human Influence and Classical Biogeographic Predictors of Rare Species Occurrence

Biogeographic theory predicts that rare species occur more often in larger, less‐isolated habitat patches and suggests that patch size and connectivity are positive predictors of patch quality for conservation. However, in areas substantially modified by humans, rare species may be relegated to the most isolated patches. We used data from plant surveys of 81 meadow patches in the Georgia Basin of Canada and the United States to show that presence of threatened and endangered plants was positively predicted for patches that were isolated on small islands surrounded by ocean and for patches that were isolated by surrounding forest. Neither patch size nor connectivity were positive predictors of rare species occurrence. Thus, in our study area, human influence, presumably due to disturbance or introduction of competitive non‐native species, appears to have overwhelmed classical predictors of rare species distribution, such that greater patch isolation appeared to favor presence of rare species. We suggest conservation planners consider the potential advantages of protecting geographically isolated patches in human‐modified landscapes because such patches may represent the only habitats in which rare species are likely to persist. Influencia Humana y Predictores Biogeográficos Clásicos de la Ocurrencia de Especies Raras     

Seasonal dynamics of macro-algae in the South Lake of Tunis

The macro-algae communities observed in the south lake of Tunis are characterized by the predominance of nitrophilous algae which are in the order of biomass importance:Ulva, Cladophora andEnteromorpha. We have noted seasonal changes of alga distribution. The wind appears to be one of the most important factors influencing this distribution. The total biomass reaches a maximum in the spring. Rapid decomposition of the biomass leads to a severe ecological imbalance, resulting in crises of anoxia and fish death. A restoration project has already started. It aims at removal of contaminated muds and the introduction of a new circulation system. The main objectives of this work were to collect information on the distribution and biomass of the phytobenthic communities as a first step in the constitution of a database for further comparison.     

Patterns and biases of climate change threats in the IUCN Red List

International Union for Conservation of Nature (IUCN) Red List assessments rely on published data and expert inputs, and biases can be introduced where underlying definitions and concepts are ambiguous. Consideration of climate change threat is no exception, and recently numerous approaches to assessing the threat of climate change to species have been developed. We explored IUCN Red List assessments of amphibians and birds to determine whether species listed as threatened by climate change display distinct patterns in terms of habitat occupied and additional nonclimatic threats faced. We compared IUCN Red List data with a published data set of species’ biological and ecological traits believed to infer high vulnerability to climate change and determined whether distributions of climate change‐threatened species on the IUCN Red List concur with those of climate change‐threatened species identified with the trait‐based approach and whether species possessing these traits are more likely to have climate change listed as a threat on the IUCN Red List. Species in some ecosystems (e.g., grassland, shrubland) and subject to particular threats (e.g., invasive species) were more likely to have climate change as a listed threat. Geographical patterns of climate change‐threatened amphibians and birds on the IUCN Red List were incongruent with patterns of global species richness and patterns identified using trait‐based approaches. Certain traits were linked to increases or decreases in the likelihood of a species being threatened by climate change. Broad temperature tolerance of a species was consistently related to an increased likelihood of climate change threat, indicating counterintuitive relationships in IUCN assessments. To improve the robustness of species assessments of the vulnerability or extinction risk associated with climate change, we suggest IUCN adopt a more cohesive approach whereby specific traits highlighted by our results are considered in Red List assessments. To achieve this and to strengthen the climate change‐vulnerability assessments approach, it is necessary to identify and implement logical avenues for further research into traits that make species vulnerable to climate change (including population‐level threats).