The impact of a macroalgal mat on benthic biodiversity in Poole Harbour

Blooms of macroalgal matting are increasingly common within temperate zones and are often comprised of opportunistic species such as Ulva lactuca. Where this algae forms a dense mat, a stressful environment is created in the sediment below, influencing the invertebrate infaunal assemblage. This study was conducted over a six month period during which a dense mat of U. lactuca developed and subsequently dispersed. The algal mat was found to have a significant negative impact on species richness, abundance and biomass of the macroinfauna. However, a faunal community developed within the algal mat which contained several species not previously observed. This community increased the abundance and diversity of the overall invertebrate assemblage. The results are discussed in relation to impacts on the ecosystem as a whole.     

Ecological consequences of dredged material disposal in the marine environment: a holistic assessment of activities around the England and Wales coastline

This study provides a holistic perspective on the ecological effects of dredged material disposal, both intertidally and subtidally. A number of numerical techniques (univariate, distributional, multivariate and meta-analysis) were used to assess impacts at 18 different disposal sites. The analyses revealed that ecological effects associated with dredged material disposal were dependent on the numerical techniques used, and that impacts were disposal-site specific. Disposal-site communities were generally faunistically impoverished to varying degrees, and impacts following intertidal placement were comparable to those of subtidal placement. We conclude that any assessment of the consequences of dredged material disposal to the coastal environment must take account of site-specific variation in prevailing hydrographic regimes and in ecological status, along with information on the disposal activity itself (mode, timing, quantity, frequency and type of material). As would be expected, variability in the latter presents a significant challenge in attempts to generalise about environmental and ecological impacts.     

Identification, definition and quantification of goods and services provided by marine biodiversity: implications for the ecosystem approach

This paper identifies and defines ecosystem goods and services provided by marine biodiversity. Case studies have been used to provide an insight into the practical issues associated with the assessment of marine ecosystem goods and services at specific locations. The aim of this research was to validate the definitions of goods and services, and to identify knowledge gaps and likely difficulties of quantifying the goods and services. A validated theoretical framework for the assessment of goods and services is detailed, and examples of the goods and services at a variety of case study areas are documented. These results will enable future assessments of marine ecosystem goods and services. It is concluded that the utilisation of this goods and services approach has the capacity to play a fundamental role in the Ecosystem Approach, by enabling the pressures and demands of society, the economy and the environment to be integrated into environmental management.     

Single crystal U-Pb zircon age and Sr-Nd isotopic composition of impactites from the Bosumtwi impact structure, Ghana: Comparison with country rocks and Ivory Coast tektites

The 1.07?Myr old Bosumtwi impact structure (Ghana), excavated in 2.1-2.2?Gyr old supracrustal rocks of the Birimian Supergroup, was drilled in 2004. Here, we present single crystal U-Pb zircon ages from a suevite and two meta-graywacke samples recovered from the central uplift (drill core LB-08A), which yield an upper Concordia intercept age of ca. 2145?±?82?Ma, in very good agreement with previous geochronological data for the West African Craton rocks in Ghana. Whole rock Rb-Sr and Sm-Nd isotope data of six suevites (five from inside the crater and one from outside the northern crater rim), three meta-graywacke, and two phyllite samples from core LB-08A are also presented, providing further insights into the timing of the metamorphism and a possibly related isotopic redistribution of the Bosumtwi crater rocks. Our Rb-Sr and Sm-Nd data show also that the suevites are mixtures of meta-greywacke and phyllite (and possibly a very low amount of granite). A comparison of our new isotopic data with literature data for the Ivory Coast tektites allows to better constrain the parent material of the Ivory Coast tektites (i.e., distal impactites), which is thought to consist of a mixture of metasedimentary rocks (and possibly granite), but with a higher proportion of phyllite (and shale) than the suevites (i.e., proximal impactites). When plotted in a Rb/Sr isochron diagram, the sample data points (n?=?29, including literature data) scatter along a regression line, whose slope corresponds to an age of 1846?±?160?Ma, with an initial Sr isotope ratio of 0.703?±?0.002. However, due to the extensive alteration of some of the investigated samples and the lithological diversity of the source material, this age, which is in close agreement with a possible "metamorphic age" of ～?1.8-1.9?Ga tentatively derived from our U-Pb dating of zircons, is difficult to consider as a reliable metamorphic age. It may perhaps reflect a common ancient source whose Rb-Sr isotope systematics has not basically been reset on the whole rock scale during the Bosumtwi impact event, or even reflect another unknown geologic event.     

地震破裂的确定性性质

了解地震破裂过程对于了解断层系统和地震危险是很重要的。关于断层破裂性质的若干假定已经提出,但还没有形成统一的理论(Brune,1979;Fukao and Furu-moto,1985;Ellsworth and Beroza,1995;Beroza and Ellsworth,1996;Dodgeet al,1996;Mori,1996;Mori and Kanamori,1996;Singhet al,1998;Steacy and McClos-key,1998;Kilb and Gomberg,1999;Sato and Kanamori,1999;Ohnaka,2000)。大多数被引用的概念上的假设是断层破裂的级联模型(Burne,1979;Ellsworth and Beroza,1995,1998;Kilb and Gomberg,1999)。在级联模型中,滑动在断层的一小段上开始,只要条件有利,并持续破裂,直至延伸到断层面。这个如同多米诺骨牌的理论有2个基本含义:小地震以大地震相同的方式开始,破裂过程是不确定性的;换句话说,直到破裂停止之前,地震大小是不能确定的。在本文中我们说明,事件最终大小与破裂最初几秒的地震能量辐射频谱成正比。我们推断,地震震级能在破裂完成之前被估算出来。这一发现意味着破裂过程在某种程度上是确定性的,并且具有破裂过程物理学的含义。     

剪断翼龙的翅膀：对于翼展估计和多样性的评论

Giant azhdarchids are perhaps the most spectacular pterosaurs known and, although they lack the elaborate headcrests or striking dentition that adorn other charismatic pterosaurs, the sheer enormity of their proportions has drawn a wealth of popular and scientific interest. Their remains, however, are so fragmentary that only limited interpretations of their anatomy and taxonomy can be made with certainty. Here, we report on recent investigations into giant azhdarchid taxonomy and size estimates that suggest both may be over-inflated.     

巴塔哥尼亚(阿根廷)中侏罗世翼龙的骨骼学特征

The Ca?adon Asfalto Formation is mainly composed of lacustrine deposits and has provided the most diverse vertebrate fauna known for the Middle Jurassic in the Southern Hemisphere. Pterosaur remains have been discovered from several localities in this unit and briefly reported by Rauhut et al. (2001) and Unwin et al. (2004).     

辽宁阜新排山楼金矿区岩浆岩锆石 SHRIMP定年及其意义

采用先进的 SHRIMP定年技术对辽宁阜新排山楼金矿区成矿前变形的闪长玢岩脉、变形花岗斑岩脉、成矿后的闪长玢岩脉和大石头沟黑云母花岗岩的锆石进行了 U Pb年龄测定 , 获成矿前变形闪长玢岩脉的 206Pb/238Pb年龄为 (126± 2)Ma; 变形花岗斑岩脉为 (124± 1)Ma; 成矿后的闪长玢岩脉为 (125± 1)Ma; 大石头沟黑云母花岗岩为 (124± 1)Ma. 这 4类岩浆岩的年龄在误差允许范围内可基本视为同时代的 . 这一结果揭示 , 排山楼韧性剪切带型金矿床是中生代燕山晚期形成的 , 这与前人采用 Ar Ar法测得矿石蚀变黑云母的年龄 [(124.4± 0.391)Ma]是一致的 . 这表明 , 在中国东部 , 许多产在前寒武系岩层中、受韧性剪切带控制的金矿床形成时代是中生代燕山晚期 . 广泛产在胶东、辽西北票 - 蒙东赤峰、河北张家口和内蒙古乌拉山等地区的金矿床都主要是中生代燕山晚期形成的 , 表明燕山晚期是中国东部最重要的金矿化期 .