Temporal variation in an immune response gene (MHC I) in anadromous Salmo trutta in an Irish river before and during aquaculture activities     

Coughlan  James; McGinnity  Philip; O'Farrell  Brian; Dillane  Eileen; Diserud  Ola; de Eyto  Elvira; Farrell  Killian; Whelan  Ken; Stet  Rene J.M.; Cross  Thomas F. 《ICES Journal of Marine Science》2006,63(7):1248-1255

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Spatial and temporal distribution patterns of deep‐sea mesozooplankton in the eastern Mediterranean – indications of a climatically induced shift?     

Rolf Koppelmann  & Horst Weikert 《Marine Ecology》2007,28(2):259-275

Zooplankton samples from the eastern Mediterranean were collected in April/May 1999 with a multiple opening and closing net (mesh size 333 μm) to examine the distribution and taxonomic composition of mesozooplankton, mainly Calanoida (Copepoda), some years after the onset of the Eastern Mediterranean Transient (EMT), a climatically induced shift in hydrography. The samples from seven stations on a transect from the Ionian Sea to the eastern part of the Levantine Basin were collected at closely spaced vertical intervals from the surface to water depths of 4250 m. Data from January 1987, June 1993, January 1998 and October 2001 from the main site of investigation, south of Crete, were used to describe the temporal evolution before (1987), during (1993) and after (1998–2001) the EMT. The eastern Mediterranean mesozooplankton fauna is dominated by three Calanoida species along the west–east transect, with varying abundances in different depth‐zones: Haloptilus longicornis in the epipelagic zone, Eucalanus monachus in the mesopelagic zone, and Lucicutia longiserrata in the bathypelagic zone. A drastic change in mesozooplankton composition and abundance occurred at the main site during the EMT, whereupon increased abundances of Candacia elongata and L. longiserrata were observed in the bathypelagic zone in the following years; L. longiserrata accounted for 43% of the total mesozooplankton in this zone. The hypothesis is posed that the Mediterranean deep‐sea ecosystem is able to respond quickly to changes in the environment and memorizes these changes over time. We claim that the biological effects of climatically induced changes can be easily monitored in the deep eastern Mediterranean Sea using calanoid copepod key species due to the hydrographically extreme, but ‘simply structured’ ecosystem.  相似文献   

Nereis diversicolor: an Unreliable Biomonitor of Metal Contamination in the 'Ría de Bilbao' (Spain)     

J. I. Saiz-Salinas  G. Francés-Zubillaga   《Marine Ecology》1997,18(2):113-125

Abstract. Samples of the polychaete Nereis diversicolor O.F. M üller and surficial sediments from a clean and a polluted estuary were taken during a year at monthly intervals to determine, by comparison, the range of temporal fluctuations in trace metal concentrations. Whereas metal variations in surficial sediments were more pronounced in the polluted estuary, concentrations in N. diversicolor in both estuaries showed a wide range of temporal variation that surpassed that of surficial sediments. A clear decline in all metals studied (except Mn) from polluted sediments was noted after episodes of strong rainfall. In the reference estuary the fluctuations were less pronounced. Metal body burdens in N. diversicolor from the two estuaries were usually quite similar even though total levels in sediments differed considerably, indicating a lack of worm-sediment relationship. The low level of Cu, Cr and Pb in the tissues of N. diversicolor suggest a mechanism which prevents the polychaete from being exposed to these metals in highly polluted sediments. Therefore, it is concluded that N. diversicolor cannot be considered to be an ideal biomonitor of metal contamination in the polluted Bilbao Estuary.  相似文献   

Factors affecting spatial and temporal variability in material exchange between the Southern Everglades wetlands and Florida Bay (USA)     

Martha A. Sutula  Brian C. Perez  Enrique Reyes  Daniel L. Childers  Steve Davis  John W. Day  Jr.  David Rudnick  Fred Sklar 《Estuarine, Coastal and Shelf Science》2003,57(5-6):757-781

Physical and biological processes controlling spatial and temporal variations in material concentration and exchange between the Southern Everglades wetlands and Florida Bay were studied for 2.5 years in three of the five major creek systems draining the watershed. Daily total nitrogen (TN), and total phosphorus (TP) fluxes were measured for 2 years in Taylor River, and ten 10-day intensive studies were conducted in this creek to estimate the seasonal flux of dissolved inorganic nitrogen (N), phosphorus (P), total organic carbon (TOC), and suspended matter. Four 10-day studies were conducted simultaneously in Taylor, McCormick, and Trout Creeks to study the spatial variation in concentration and flux. The annual fluxes of TOC, TN, and TP from the Southern Everglades were estimated from regression equations. The Southern Everglades watershed, a 460-km² area that includes Taylor Slough and the area south of the C-111 canal, exported 7.1 g C m⁻², 0.46 g N m⁻², and 0.007 g P m⁻², annually. Everglades P flux is three to four orders of magnitude lower than published flux estimates from wetlands influenced by terrigenous sedimentary inputs. These low P flux values reflect both the inherently low P content of Everglades surface water and the efficiency of Everglades carbonate sediments and biota in conserving and recycling this limiting nutrient. The seasonal variation of freshwater input to the watershed was responsible for major temporal variations in N, P, and C export to Florida Bay; approximately 99% of the export occurred during the rainy season. Wind-driven forcing was most important during the later stages of the dry season when low freshwater head coincided with southerly winds, resulting in a net import of water and materials into the wetlands. We also observed an east to west decrease in TN:TP ratio from 212:1 to 127:1. Major spatial gradients in N:P ratios and nutrient concentration and flux among the creek were consistent with the westward decrease in surface water runoff from the P-limited Everglades and increased advection of relatively P-rich Gulf of Mexico (GOM) waters into Florida Bay. Comparison of measured nutrient flux from Everglades surface water inputs from this study with published estimates of other sources of nutrients to Florida Bay (i.e. atmospheric deposition, anthropogenic inputs from the Florida Keys, advection from the GOM) show that Everglades runoff represents only 2% of N inputs and 0.5% of P input to Florida Bay.  相似文献   

基于时刻独立脉冲耦合神经网络的高空间分辨率摇感影像分割     

李利伟  马建文  欧阳赟  温奇 《遥感学报》2008,12(1):64-69

高空间分辨率遥感影像中地物目标内部光谱信息复杂性的增强,使得传统基于光谱特征值的数据处理方法效果不再显著,影像分割为解决这一问题提供了一种思路,成为当前高空间分辨率遥感影像处理的研究焦点.时刻独立脉冲耦合神经网络具有状态相近、空间相邻神经元相互耦合同步脉冲激发和区域之间神经元脉冲激发时刻独立两大特点,已被应用于非遥感影像分割中,并取得较好效果.本文结合高空间分辨率遥感影像特点,通过对网络参数进行实验和分析,提出一个基于时刻独立脉冲耦合神经网络的高空间分辨率遥感影像分割方法,并利用空间分辨率0.3m的航空影像进行了数据试验,将分割结果进行讨论并与现有时刻独立脉冲耦合神经网络方法和ISODATA方法分割结果进行对比分析.结果表明:时刻独立脉冲耦合神经网络在高空间分辨率遥感影像分割处理中具有很好的应用前景.  相似文献   

辽宁铁岭市土壤侵蚀时空演变研究   总被引：2，自引：0，他引：2  

王燕  姚玉增  巩恩普  姚志宏 《中国地质灾害与防治学报》2008,19(3):144-147

近年来,人为活动的加剧造成铁岭地区水土流失日益严重。本文采用遥感和GIS技术,以部颁标准SL190-96对铁岭地区1991年和2001年的土壤侵蚀情况进行研究,并结合1986年和1996年的土壤侵蚀调查数据,分析了铁岭地区近15年来土壤侵蚀强度的时空变化,结果表明铁岭地区在此期间土壤侵蚀面积缓慢增长,其中强度侵蚀面积在1986~1996年间持续增长,2001年明显下降;中度侵蚀面积在1986~1996年间持续下降,2001年则明显增强;空间分析显示明显恶化的区域有西丰、开原和清河区,具明显改善的为铁岭县,而昌图和调兵山地区基本保持稳定。今后该区水保的重点应放在强度侵蚀的治理,以及土壤侵蚀等级增强的区域。  相似文献   

基于ArcObjects的土地利用时空分析系统研究     

白明哲  岳秋丽  张健雄 《测绘与空间地理信息》2008,31(3)

随着愈加快速的土地资源开发,土地利用时空变化研究已全面启动,本文结合ArcObjects组件、Access数据库和VC 工具开发了一个土地利用时空分析系统,实现了土地利用空间数据建库、地图查询分析、土地利用时空模型解算等功能。为土地利用时空研究提供功能集成的数据运算与图形处理平台,也为土地利用规划的制定及其修编等工作提供了技术支持。  相似文献   

Research on temporal and spatial distribution, evolutionary character and mechanism of crustal deformation field before and after the Tangshan earthquake   总被引：2，自引：0，他引：2  

周硕愚  施顺英  帅平 《地震学报(英文版)》1997,10(6):693-701

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Water chemistry and water quality variation in the Danjiangkou Reservoir, as a function of water management for the Middle Route of South to North Water Divert Project, China     

Siyue LI Quanfa ZHANG 《中国地球化学学报》2006,25(B08):274-274

As the diversion dike of the Middle Route of the South to North Water Transfer Project （MRSNWTP）, the water quality and water quantity of Danjiangkou Reservoir is critical to the project. At present, the rates of industrial wastewater treatment and sewage discharge, which belongs to Chinese State Standard in the districts near the reservoir except Shiyan city, are less than 60% and 40% respectively. The point source pollutants will be controlled because of the project after some time, but the non-point source pollutants caused by vegetation degradation and water-soil erosion will not be controlled effectively in a long time. Water samples were collected from the Danjiangkou Reservoir during 2004 and 2005 and analyzed for trace metals, i.e., silver （Ag）, aluminum （Al）, arsenic （As）, barium （Ba）, bismuth （Bi）, calcium （Ca）, cadmium （Cd）, cobalt （Co）, chromium （Cr）, copper （Cu）, iron （Fe）, mercury （Hg）, potassium （K）, lithium （Li）, magnesium （Mg）, manganese （Mn）, molybdenum （Mo）, sodium （Na）, nickel （Ni）, lead （Pb）, antimony （Sb）, selenium （Se）, silicon （Si）, strontium （Sr）, vanadium （V）, zinc （Zn）, chemicophysical parameters and nutrients, i.e., temperature （T）, pH, dissolved oxygen （DO）, turbidity, total suspended solid （TSS）, nitrate/ammonia/ammonium-nitrogen （NO3^-/NH3/NH4^＋-N）, total nitrogen （TN）, dissolved inorganic nitrogen （DIN）, total phosphorus （TP）, potassium permanganate index （IMn）, biochemical oxygen demand （BOD）, dissolved inorganic carbon （HCO3^-）. Our results are water quality belongs to Chinese standard level II, trace metals are low, but they are accumulating, and many of which, i.e., As, Pb, will endanger reservoir water security.  相似文献   

东北夏季(6-8月)气温异常的时空特征分析   总被引：5，自引：0，他引：5  

李兰  王盘兴  陈长胜  李丽平 《南京气象学院学报》2005,28(6):801-807

利用夏季（6—8月）中国东北地区91站44a气温资料，采用谐波分析方法将该区夏季气温异常变化的年代际、年际尺度分量分离，研究时空特征，然后应用REOF进行气温异常的区划，研究局域异常变化的年代际、年际分量的变化特征。结果发现：1）东北各站夏季异常方差中，东北大部分地区的气温异常的年代际变化分量均明显大于年际变化分量。2）区域气温异常的年代际变化主要特征为线性上升趋势。大范围夏季异常高温（低温）常出现在年代际、年际异常同时为正（负）的年份。3）气温异常可划分为南部型、北部型、东部型、西部型4个型，其中南部型和西部型的年代际变化相对重要，而东部型和北部型的年际变化相对重要。  相似文献