Allelopathy at the land/sea interface: microalgae and Brazilian pepper

Microalgae are significant contributors to biodiversity and primary production in shallow coastal habitats. The invasive Brazilian pepper (Schinusterebinthifolius) can occupy former mangrove habitats in disturbed areas, and its allelopathic capability can affect growth rates of microalgae. The four microalgae tested against dilution extracts of Schinus fruits varied in their growth response, suggesting variable but unpredictable impacts on microalgal biodiversity, primary production, and community structure.     

The use of soft X-ray spectromicroscopy to investigate the distribution and composition of organic matter in a diatom frustule and a biomimetic analog

Diatoms play a significant role in the global carbon cycle through their role in biogenic silica production and the transport of organic matter to the seafloor. Recent work has shown that silicified diatom frustules contain a significant amount of organic matter, and that the proportion of diatom-bound organic matter increases with depth in the water column and sediments. Here, we investigate the association between organic matter and the mineral phase. We used a combination of scanning transmission X-ray microscopy (STXM) and carbon X-ray absorption near-edge structure (XANES) spectroscopy to characterize the distribution and composition of organic matter in frustules of the diatom Cylindrotheca closterium and a biomimetic silica gel. To our knowledge, this study represents the first successful attempt to simultaneously image and obtain chemical information about the organic matter within a diatom frustule using X-ray spectromicroscopy near the carbon edge. Organic carbon, most likely protein, was distributed throughout the frustules and was not removed by harsh chemical treatment. The physical structure of the frustules appeared to be related to the chemical composition of this organic matter, with aromatic or unsaturated carbon being concentrated in the most intricately patterned regions of the frustule. A similar physical and chemical structure was observed in a biomimetic silica gel precipitated spontaneously with polylysine. These results are consistent with the theory that organic constituents of diatom frustules direct silica precipitation and become incorporated within the silica matrix as it forms. The relationship between organic matter composition and silica morphology, the failure of harsh chemical treatments to remove this organic matter, and the spontaneous nature of the co-precipitation of silica and organic matter indicate some chemical interaction between the siliceous and organic components of diatom frustules. Frustule-bound organic matter should therefore be protected from decomposition in the water column or diagenetic alteration in sediments unless the frustule dissolves.     

海洋硅藻稳定同位素研究进展

对海洋初级生产力贡献约40%的硅藻,在全球气候与碳循环中扮演着重要的角色。硅藻稳定同位素(δ30Si和δ18O,δ13C和δ15N)测试对象分别为从海洋沉积物中提取的纯硅藻壳体的生物硅和氧及其内嵌有机质的碳和氮。联合运用各种物理分离(去有机质、碳酸盐,筛分,差异沉降,重液浮选以及微池分流重力场流分离技术)和化学纯化技术从沉积物中提纯出硅藻是其稳定同位素古海洋学应用的前提。确定硅藻δ15N两种制样过程(燃烧和湿式消解)中是否分别存在大气N2和非NO3-组分的污染;δ30Si分析中氟化剂使用的避免、制样方法的改进以及MC-ICP-MS对硅同位素分辨能力的提高;δ18O分析中硅藻壳体外层不稳定氧的完全有效去除,是其同位素古海洋学应用范围扩大和精度提高的关键。硅藻δ13C能评估大气PCO2和海洋初级生产力变化;δ15N和δ30Si可定量示踪海洋硝酸盐和硅酸等营养物利用程度;δ18O则记录了海表温度和海水氧同位素组成。硅藻稳定同位素信号单一,受后期改造作用弱,生命效应低,解译针对性强,在两极和赤道少(或缺)有孔虫海区应用广泛。在此基础上,对目前该领域中存在的问题及未来的研究方向进行了阐述。     

从藻类化石的垂直分布探讨杭州西湖的演变历程

于１９９４年春在杭州西湖东北面,西面及湖中心小瀛洲３个钻孔共取了７０号岩芯样,经浮选,筛选,以显微镜检鉴定化石藻种,并分析其垂直分布,从而探讨西湖的形成历史,西湖自晚更新世以来的６个化石藻带由下而上依次为：轮藻带,微藻带,微红金颗藻－近缘针杆藻－条纹小环藻带,圆筛藻带,圆筛藻－近缘针杆藻－微红金颗藻桥穹藻－异极藻－短缝藻带和水花束丝藻带,从而反映了西湖的６个发育时期,淡水古湖沼期,淡咸水过渡期,海     

虾青素对饲料组胺胁迫下美洲鳗鲡(Anguilla rostrata)幼鱼生长性能、血清生化、肠道自由基水平及肠道菌群的影响

氧化应激是饲料组胺胁迫对鱼体产生危害的主要途径之一。研究具有强抗氧化能力的虾青素对美洲鳗鲡幼鱼饲料组胺胁迫的缓解效果, 对降低鱼类饲料源胁迫具有重要意义。将400尾初始体重为(25.01±0.17) g/尾的试验鱼随机分为4个处理组, 即对照组、H组、H+Ast4组和H+Ast8组, 分别饲喂基础饲料、高组胺饲料(662 mg/kg)及在高组胺饲料中添加4 mg/kg、8 mg/kg虾青素的试验饲料。结果显示: 与对照组相比, H组美洲鳗鲡幼鱼生长性能和血清非特异性免疫能力显著降低(P<0.05),肠道自由基水平显著升高(P<0.05),肠道有害菌群丰度升高; H+Ast组美洲鳗鲡幼鱼的生长性能、血清非特异性免疫能力显著高于H组(P<0.05),肠道自由基水平显著低于H组(P<0.05), 上述指标H+Ast组与对照组无显著差异(P>0.05)。H+Ast组肠道有益菌群丰度高于H组和对照组。可见, 添加4 mg/kg虾青素即可缓解饲料组胺胁迫导致的美洲鳗鲡幼鱼生长抑制, 提高血清非特异性免疫能力, 降低肠道自由基水平, 有益调节肠道菌群。添加8 mg/kg虾青素对美洲鳗鲡幼鱼上述指标无进一步的改善效果。研究结果可为虾青素缓解美洲鳗鲡饲料组胺胁迫及其在饲料中的推广应用提供参考。     

Exceptional preservation of Upper Carboniferous (lower Westphalian) fossils from Edlington,Doncaster, South Yorkshire,UK

A new fossil‐bearing, Upper Carboniferous (lower Westphalian) locality in Doncaster, South Yorkshire, UK, is reported and an account of the fossils is presented. The diverse flora and fauna consists of plants, bivalves, arthropods (primarily xiphosurans), tentaculitids (microconchids), fish scales, shark egg capsules and coprolites. Fossils are preserved in siderite nodules and shales, and display excellent preservation and detail. Previous collecting of Carboniferous fossils in the Doncaster area has been minimal. The discovery of this locality addresses this deficit and is of further importance as such localities in the UK are diminishing in number with the cessation of coal‐mining and the reclamation of mine dumps, further demonstrating the importance and recognition of the Edlington site. Copyright © 2014 John Wiley & Sons, Ltd.     

塔吉克斯坦种子植物区系分析

塔吉克斯坦区系位置特殊、物种独特丰富,研究其植物区系特点对于进一步全面了解中亚植物资源现状、起源及演化具有重要意义。通过文献搜集、野外调查和标本查阅,对塔吉克斯坦种子植物区系特点进行了分析。结果表明：塔吉克斯坦境内共有种子植物4 115种,隶属于110科864属,种子植物丰富、种类分布表现出多数种集中于少数科属中,同时单种及寡种科属多的两端分布的特点;植物区系主要表现为温带性质,但也受到热带植物区系的深远影响,区系成分复杂、过渡特征明显,特有属少。特有成分在种级水平上分化明显,种子植物区系性质表现出与所处自然地理条件的一致性。     

贺兰山北段晚石炭世晚期和早二叠世早期植物群古生态学的研究

在综合研究了贺兰山北段晚石炭世晚期和早二叠世早期植物群的特征和性质的基础上 ,对此植物群进行了古生态学方面的分析研究。采用了传统的埋藏学研究模式 ,对不同地区植物化石分别进行了埋藏学的研究 ,得出本区植物群的主要埋藏类型为原地埋藏 ,其次为亚原地埋藏 ,有极少量为异地埋藏。其化石群落基本能反映当时植物群的生活面貌 ,再结合分异度的数据恢复了古群落。此外 ,根据植物群的特征分析 ,得出当时的古气候应为赤道低纬度地区的热带雨林气候     

西藏措勤—申扎地层分区二叠系敌布错组的建立及其特征

敌布错组为1∶25万措勤区幅区域地质调查首次发现并建立的岩石地层单位。该组角度不整合于下二叠统下拉组之上,盛产冈瓦纳—华夏混合植物群化石,岩性组合呈现灰色复陆屑建造的特点,厚度大于830m。层型剖面位于西藏措勤县江让乡敌布错北缘(E84°46',N30°51')。2001年夏经专家实地考查确认,该剖面已完全具备建组条件。此套岩石组合的发现为进一步完善冈底斯构造带古生代地层系统提供了新的资料。     

Zinc in Fish, Crabs, Oysters, and Mangrove Flora and Fauna from Cleveland Bay

Zinc in muscle tissue from 28 species of fish, three species of sharks and rays, two species of squid and cuttlefish, and three species of crustacea collected from Cleveland Bay, together with some measurements made on oysters and mangrove flora and fauna are reported. In the fish species the mean Zn concentration in muscle tissue was 4.83 ± 2.82 μg/g wet weight, slightly lower than zinc measurements (7 μg/g wet weight) made in 14 fish species collected from the bay in 1975. Zinc in sharks and rays ranged from 3.5 to 7.2 μg/g wet wt, in squid and cuttlefish 13–16 μg/g wet wt, and in crustacea levels ranged from 14 to 18 μg/g wet wt. Zinc levels in fish varied between species with concentrations well below the ANZECC Maximum Residue Limit of zinc in seafood (150 μg/g wet wt). Although lower zinc concentrations were found in oysters collected from the Townsville Harbour area (2080 μg/g wet wt), compared with previous measurements made 25 years ago at this site, these levels are still above the Maximum Residue Limit for zinc in oysters (1000 μg/g wet wt). Concentrations of zinc in oysters from Orpheus Island (2547 μg/g wet wt), about 74 km away from industrial and urban activity, are also above the safe guideline values. Horseshoe Bay oysters transplanted to Ross Creek accumulated zinc at a rate of about 100 μg/g of oyster tissue per week, suggesting that dissolved zinc levels at this site are elevated, and that oysters rapidly accumulate zinc. Highest concentrations of zinc in mangrove leaves (30–65 μg/g dry wt) occurred in Osbornia octodonta, Exocaria agalocha, and Aegialitus annulata, compared with Ceriops tagal, and Avicennia marina (5–10 μg/g dry wt). No significant difference in zinc concentration occurred between leaves and litter fall for most of these species, with the sole exception of Exocaria, which showed almost a twofold increase in concentration. In seven species of mangrove fauna levels of zinc were very uniform and close to 50 μg/g (dry wt) Telescopium telescopium from the mouth of the Ross Estuary was the exception with levels at 400 μg/g (dry wt).