Meiofaunal responses to nutrient additions in a Mediterranean stream

1. The effects of a moderate addition of nutrients (twofold N and threefold P) were examined during a 2‐year period to determine the response to nutrient addition in a meiofaunal community inhabiting sandy patches in a Mediterranean stream. 2. The pattern of meiofaunal assemblages exhibits a high degree of intra‐ and interannual variability. This pattern alternates between periods of hydrological stability and disturbances, such as floods and droughts, which is a characteristic of Mediterranean systems. 3. A before–after–control–impact (BACI) design was used to determine the outcome of the addition by comparing an upstream non‐enriched reach with an enriched downstream reach. Analysis of the study data by means of a nonparametric permutational procedure (permanova ) showed that fertilisation had a significant effect. Density and biomass values increased in the most abundant meiofaunal groups, including microcrustaceans, oligochaetes and chironomids. Microcrustaceans were the dominant group in the permanent meiofauna. 4. We also examined differences in microcrustacean secondary production in both reaches. Ostracods and cyclopoid copepods increased their secondary production in the impacted reach as a result of the nutrient addition. 5. Our study demonstrated that moderate nutrient enrichment can affect the biomass and production of stream meiofauna, but it is still unclear whether this effect was because of autotrophic or heterotrophic pathways.     

The Ordovician-Silurian boundary stratotype: consequences of its approval by the IUGS

Lespérance, Pierre J., Barnes, Christopher R., Berry, William B. N., Boucot, Arthur J. & Mu En-zhi 1987 07 15: The Ordovician-Silurian boundary stratotype: consequences of its approval by the IUGS.
The Ordovician-Silurian stratotype at Dob's Linn, Scotland is the second systemic boundary approved by the International Union of Geological Sciences (IUGS). A review of the internationally accepted criteria required of a stratotype shows that few of these are possessed by the Dob's Linn section. The strongest attribute of the section is the presence of zonal graptolites, although the boundary is recognized primarily on a single biological event (base of acuminatus Zone) for which the evolutionary relationships of the taxa are not established. In approving this boundary proposal in 1985, which received only simple majority support within the Ordovician-Silurian Boundary Working Group (OSBWG) and which fails to meet most of the accepted prerequisites for a stratotype, the International Commission on Stratigraphy (ICS) and the IUGS have established an unfortunate precedent. It follows that future systemic boundaries need not meet the accepted standards. It raises serious questions on the assessment and voting procedures of the International Commission on Stratigraphy and on the credence accorded the recommendations developed by the International Subcommission on Stratigraphic Classification of IUGS.     

Description of the Infraciliature and Morphogenesis in the Ciliate Urotricha ondina N. Sp. (Prorodontida, Urotrichidae)

Recent works on prostomatid ciliates show that some genera of this group have a differentiated oral infraciliature and that their stomatogenesis during division involves the proliferation of only a few somatic kineties. These findings have significant implications regarding the iaxonomic status of these genera and also on the terminology used for the oral structures. In Urotricha ondina , the oral infraciliature consists of (1) a paroral kinety formed of paired kinetosomes that encircle the cytostome at the anterior pole of the cell and (2) 3 adoral organelles, each formed of 2 rows of kinetosomes, ventral in position and obliquely disposed, lying above 3 short somatic kineties that do not reach the anterior pole of the cell. This oral ciliature —formerly known as the corona and brosse, respectively—originate during stomatogenesis from the proliferation of 4 somatic kineties that lie posterior to the adoral organelles of the parental cell.     

Entamoeba histolytica: Collagenolytic Activity and Virulence1

Several axenic strains of pathogenic and nonpathogenic Entamoeba histolytica were tested for their capacity to digest native radioactive type I collagen gels and to produce liver abscesses when injected into the liver of newborn hamsters. The results demonstrate that the pathogenic strains of amebas (HM1:IMSS, HM3:IMSS, HM38:IMSS, and HK9) have a collagenolytic activity that closely correlates with their in vivo capacity to produce liver lesions. The nonpathogenic isolate (Laredo) did not show collagenolytic activity and failed to produce lesions in the liver of newborn hamsters. The results also demonstrate that type I collagen obtained from rodents and cats is degraded less by amebic collagenase than is bovine collagen, which is similar to human collagen. These findings suggest that species susceptibility to invasive infection may depend, among other factors, on the characteristics of the extracellular components of host tissues.     

高含量、低用量颗粒剂防治玉米螟的研究

1973—1977年,作者研究了防治玉米螟颗粒剂的“高含量、低用量”问题,即在单位面积上有效成分用量相等下,探讨逐步提高颗粒剂中有效成分含量而又按比例减少单位面积上颗粒剂用量的防治效果的相关性。结果证明,在相当大的范围内,高含量、低用量可以代替低含量、高用量。每亩用辛硫磷4克时,1.6%颗炷剂每亩用0.5斤与0.1%颗粒剂每亩用8斤均可获80%左右相似的防治效果;每亩用对硫磷40克时,8%颗粒剂每亩用1斤与1%颗粒剂每亩用8斤均可获90%以上防治效果。对地亚农和二氯苯醚菊酯试验亦获类似结果。 颗粒剂应用这一改革,有利于成品化和机械施药,并可显著降低防治成本。 同时,还做了室内毒力测定及在玉米上残效作用测定,以验证田间防治效果。 近二十年来,国内、外一直把颗粒剂做为防治玉米心叶期玉米螟(`Ostrinia nubilalis`` Hübner)的有效手段。我国自五十年代末已开始研究和应用滴滴涕、六六六等颗粒剂防治玉米螟,获得了高于六六六药液灌心的防治效果(邱式邦等,1961;邱式邦等,1963;慕立义,1963)。但由于颗粒剂用量大、费用高而未能成批生产。土法生产、群制群用的颗粒剂亦存在着缺点:(1)加工时不但造粒、选粒用工多,而且粒度、有效成分的含量及在载体上的分布均难以规格化,药效不够稳定;(2)加工所用的毒剂均为农药制剂。如用乳油、除乳化剂及有机溶剂被浪费外,往往还引起玉米的药害;如用粉剂,则不能渗入载体内部,不耐雨水冲洗而降低残效;(3)由于颗粒剂不规格化和单位面积用量大而不利于机械施药。因此,多年来生产上迫切需要高效、低毒、低残毒、价廉和利于机械施药的成品颗粒剂以代替土法生产的颗粒剂。     

表面活性剂对嗜盐嗜碱硫碱弧菌D301生成及利用硫颗粒的影响

【背景】微生物脱硫是脱除气体中硫化氢的一种有效方法,其中,硫颗粒的生成与代谢是控制生物脱硫效率的关键,但目前相应的控制方法很少。【目的】研究不同种类表面活性剂对硫碱弧菌D301生成及利用硫颗粒的影响。【方法】通过摇床培养,利用X射线衍射、冷场发射扫描电镜、能谱分析及傅里叶红外光谱对硫颗粒进行表征。【结果】单质硫主要以S8形式存在,吐温-80和十二烷基磺酸钠(Sodium Dodecyl Sulfate,SDS)的添加对硫颗粒的形态及生成量影响明显。对照组中生成的硫颗粒呈规则球形,光滑完整,其表面附着蛋白质等生物大分子;加入0.01 g/L吐温-80后,硫颗粒呈长杆状、颗粒增大、利用速率减慢;加入0.3g/L的SDS后,硫颗粒呈短棒状、生成量减少、利用速率加快,同时延缓了硫碱弧菌D301的衰亡。【结论】添加表面活性剂可以改变硫颗粒形态并且影响其利用,是一种调控硫颗粒生成和代谢的有效手段。     

长白山亚高山针叶林沼泽湿地碳源/汇沿水分环境梯度变化规律

高纬度和高海拔区为气候变化敏感区,该区域湿地碳循环与气候反馈关系倍受关注。为探究在全球变暖背景下高海拔区沼泽湿地碳源/汇功能是否发生了转化,以长白山高海拔区沿水分环境梯度分布的5种沼泽类型(草丛沼泽-C、灌丛沼泽-G、落叶松泥炭藓沼泽-LN、落叶松藓类沼泽-LX、落叶松苔草沼泽-LT)为对象,采用静态箱-气相色谱法和相对生长方程法,同步测定各沼泽类型全年尺度上的土壤异养呼吸碳排放量(CO₂和CH₄)、植被年净固碳量及相关环境因子(温度、水位和土壤有机碳等),并依据生态系统净碳收支平衡,量化各沼泽类型的碳源/汇作用,揭示其沿水分环境梯度变化规律及形成机制。结果表明：(1)5种沼泽类型土壤CO₂年均通量((97.68±8.64)—(291.01±18.31)mg m^-2 h^-1)沿水分环境梯度呈阶梯式递增规律性(环境梯度上部生境地段的落叶松苔草沼泽和落叶松藓类沼泽最高,中部生境地段的落叶松泥炭藓沼泽和灌丛沼泽居中,草丛沼泽最低);(2)CH₄年均通量((-0....     

海洋保护地社区多元化生计与生态系统服务的依赖关系

海洋保护地在主要承担典型海洋生态系统、珍稀濒危物种、重要自然资源自然遗迹和人文资源有效保护的同时,兼具生态功能维持、资源可持续利用与社区经济持续发展等多重任务,普遍面临着生态保护与社区生计发展间的依赖-冲突关系,探究社区生计与生态系统服务间的依赖关系,对实现海洋保护地与社区协调发展具有重要意义。基于山东长岛海洋保护地的415户社区居民的调研数据,运用可持续生计分析框架和生态系统服务依赖度模型,分析社区居民的生计资本和生态系统服务依赖度(IDES) 的特征,进一步结合多元回归模型探究生计资本对 IDES 的影响。结果表明:(1)社区居民生计资本得分呈现出由渔业主导型向务工主导型、旅游主导型、渔业兼业型递增的总趋势,且不同类型社区居民的生计资本结构具有较大差异;(2)渔业兼业型和旅游主导型社区居民从生态系统获取的收益显著高于其它居民,IDES总指数由大到小排序依次为渔业主导型、旅游主导型、渔业兼业型、务工主导型,且渔业主导型生计的供给服务依赖度显著高于其他类型,文化服务依赖度最低;(3)生计资本对不同类型居民的供给、文化服务依赖度的影响存在差异,海上养殖规模、渔业作业范围、接受政府技能培训次数、生态补偿政策、社会组织参与程度、旅游扶持政策惠及程度等指标是平衡居民生态系统服务依赖结构的关键。基于此,从不同类型居民以及当地政府多个角度提出提高长岛海洋保护地社区居民生计资本水平,优化生态系统服务依赖结构的建议,以期为实现海洋保护地与社区的协调发展提供参考借鉴。