Effects of point-source nutrient addition and mussel removal on epibiotic assemblages in Perumytilus purpuratus beds

The objective of this study was to evaluate the effects of point-source nutrient addition and mussel removal on species diversity of the epibenthic assemblage of the purple mussel Perumytilus purpuratus. It was hypothesised that mussels cushion the effects of disturbance on the associated organisms and thereby favour species diversity in patches with added nutrients. In order to test this hypothesis, a two-factorial field experiment was conducted at an exposed rocky shore of northern-central Chile in which nutrient addition and mussel removal were manipulated with two levels. Experimental units consisted of 100-cm² mussel plots that were sampled after two months of experimental manipulations. Local nutrient addition was done with coated slow-release fertilisers. Mussel removal treatments consisted in three destructive events applied throughout the experimental phase, and each event consisted in the removal of 20% of the mussel biomass from each plot. While point-source nutrient addition had only minor effects on diversity, mussel removal had significant and negative effects on faunal species richness and the abundance of suspension-feeders and sessile organisms. The abundance of predators/scavengers significantly decreased with mussel removal in the presence of nutrient addition. Grazers and mobile organisms were very abundant in the mussel assemblage but their abundance remained unaffected by treatments. Finally, species richness and total abundance of algae were also not affected by the treatments. Although the duration of our experiment was relatively short, we suggest that the effects of local nutrient addition are of minor importance at the study site in comparison to the effects of mussel removal. Based on our results and previous studies conducted in soft-bottom systems, we suggest that physical and biological stress acting on exposed hard-bottom communities overshadows the potential effects of local nutrient addition.     

山东荣成成山头“柳夼红层”的层序、划分与成因及其气候意义(Ⅱ)

四、“柳夼红层”的物质组成 本文(Ⅰ)所列“柳夼红层”剖面地层层序进行了物相、粒度、X衍射和ESR年代测定,其结果与宏观观察结果相吻合。 “柳夼红层”,剖面序列,层位和时代有所不同,成因有别,而在物质组成上却大同小异,表现出从晚更新世早期至全新世地层,其物源供应基本相同,都来源于燕山期斑状花岗岩的风化破碎产物,属就地近源搬运。     

Fish Assemblages of Posidonia oceanica Beds at Port-Cros (France, NW Mediterranean): Assessment of Composition and Long-Term Fluctuations by Visual Census

Abstract. Observations of the fish fauna of Posidonia oceanica (L.) DELILE seagrass beds were undertaken in two shallow stations and one deeper station in Port-Cros National Park, between November 1984 and September 1987. Demographic structure, density and biomass of the 19 most abundant species or taxa were assessed by several non-destructive sampling methods. The fish assemblages studied were dominated in number and biomass by a small number of species (Labridae: Symphodus ocellatus and S. tinca ; Sparidae: Diplodus annularis and Sarpa salpa ). Large individuals were infrequent and small size class fish were dominant especially in sheltered shallow areas. Recruitment and migrations (shortor long-term) have been identified as the most important causes of abundance variations over the year. The four trophic categories were sampled only in the sheltered shallow zone, where the herbivore Sarpa salpa represents a strong proportion of the fish fauna (40–70%) during summer. The fish assemblages differ between the three seagrass beds, and the depth appears as the most important factor affecting the fish assemblages in P. oceanica . The functional difference between shallow and deeper seagrass beds is therefore discussed.     

黑色页岩建造中的贵金属矿产评价研究

黑色页岩建造中的贵金属矿床是近年来不断发现的一种新矿床类型，亦是目前非传统矿产资源研究的一个重要内容．根据形态特征将该类矿床分为两类：一类是矿化厚度几十米至几百米，长度可达几公里的矿带；如俄罗斯干谷Au-Pt矿床；二是矿体厚度小(1—2cm)，长度大，金属含量高，如波兰Kupferschiefer含贵金属的Cu-Ag矿床．本文在综合分析大量国内外文献的基础上，通过对典型矿床的剖析．系统阐述了这类矿床的成矿地质背景、时空分布、矿化特征、成矿作用以及成因模型；同时分析了在我国寻找这类矿床的潜力．     

红层M形路堑边坡特征及病害的初步研究

在对红层地区渝綦、綦万高速公路路堑边坡调查的基础上,提出了M形路堑边坡的概念,并总结了其特点;简要分析了红层和坡残积层物质的岩土矿物成分和结构特征,探讨了红层M形路堑边坡病害发生的类型及形成原因,为边坡稳定性评价与采取合理的边坡加固措施提供了依据。     

Biostratinomy and facies analysis of the upper Cretaceous oyster storm shell beds of the Duwi formation, Qusseir District, Red Sea Region, Egypt

The Maastrichtian oyster Lopha villei (Coquand) occurs abundantly in the upper part of the Duwi Formation in the Red Sea region, Egypt. It forms thin undulating sharp-based shell beds that comprise both reclining and encrusting morphotypes of Lopha villei. Bed-by-bed biostratinomic and facies analyses of these shell beds confirm their shallow marine origin and formation by storm events. A tempestite model, explaining the mode of formation and the idealized sequence of events of such storm shell beds, has been inferred.     

反射系数（K）法在确定红层地质构造中的应用

以实例说明采用反射系数（Ｋ）法解释电测深ρＳ曲线,能有效地区分红层中不同类型的地质构造。     

贵金属首饰品精铸原料的研制

贵金属首饰品精铸原料的研制章晓兰廖立兵梁育林（中国地质大学,北京１０００８３）关键词贵金属白金精铸原料铸型国内珠宝行业欣欣向荣,贵金属首饰需求量逐年上升,对贵金属铸粉的需求量很大。国外首饰品精铸原料已有成熟产品,目前国内几乎所有首饰品铸造厂均使用美国...     

辽西含鸟化石层同位素年龄讨论——来自磁性地层的证据

通过对辽西及邻区白垩纪不同剖面的磁性地层资料的综合分析,对比国际中生代地磁极性年表,指出义县组含鸟化石层的地质时代至少应老于M13正极性时(129.6Ma)所对应的地质年代,介于131.71～142.27Ma之间。综合研究表明,Swisher等通过沉凝灰岩中透长石Ar-Ar法测定的义县组含鸟化石层的同位素年龄(124.6±0.2)Ma值得商榷。