Tidal and annual variability of the population structure of Eurytemora affinis in the middle part of the Seine Estuary during 2005     

David Devreker  Sami Souissi  Juan Carlos Molinero  Delphine Beyrend-Dur  Fernando Gomez  Joelle Forget-Leray 《Estuarine, Coastal and Shelf Science》2010

Annual variability in abundance and population structure of the copepod Eurytemora affinis was studied in the maximum turbidity zone of the Seine Estuary in 2005. An Eulerian sampling strategy was applied monthly from March to July and from September to December. Chlorophyll a and suspended particulate matter (SPM) concentration, copepod abundance and stage distribution, and phytoplankton abundance were measured in sub-surface and near-bottom water during the ebb phase. Total E. affinis abundance was at a maximum in March and April (>200 × 10³ ind. m⁻³), and decreased from May to September (<25 × 10³ ind. m⁻³). This decrease corresponds to annual increases in temperature, salinity, chlorophyll a concentration and phytoplankton abundance, which was dominated by large diatoms, and decreases in SPM and river discharge. The phenology observed in 2005 was almost two months earlier compared to previous studies in the 1990s, when E. affinis reached maximum abundance in May and June. The low proportion of nauplii (<50%) in the population and high abundance of ovigerous females suggests that low recruitment is probably related to anomalously low temperatures in late winter (<5 °C). Whatever the horizontal position of the population in the estuary, adult and late copepodid stages are distributed in higher salinity than naupliar stages. Overall E. affinis population abundance was driven by parameters that characterize water masses at the tidal scale and by river discharge and chlorophyll a at the annual scale. By integrating the tidal effect, the high-frequency sampling protocol used appears to be optimal for investigating annual variability of planktonic communities in megatidal estuaries.  相似文献   

Transport of nutrients and organic matter in a mangrove swamp     

Y. Akamatsu  S. Ikeda  Y. Toda 《Estuarine, Coastal and Shelf Science》2009

Field observations of the tidal transport of nutrients and organic matter in a mangrove swamp on Ishigaki Island, Okinawa, Japan revealed that groundwater flow from the swamp plays a significant role in increasing concentration of dissolved inorganic phosphorous and organic matter in a major channel. In contrast, dissolved inorganic nitrogen is transported from the mangrove swamps via surface water flow in the small channels of the swamp.  相似文献   

Tidal exchange between a freshwater tidal marsh and an impacted estuary: the Scheldt estuary, Belgium   总被引：1，自引：0，他引：1  

Stefan Van Damme  Dehairs Frank  Tackx Micky  Beauchard Olivier  Struyf Eric  Gribsholt Britta  Van Cleemput Oswald  Meire Patrick 《Estuarine, Coastal and Shelf Science》2009,85(2):197-207

Tidal marsh exchange studies are relatively simple tools to investigate the interaction between tidal marshes and estuaries. They have mostly been confined to only a few elements and to saltwater or brackish systems. This study presents mass-balance results of an integrated one year campaign in a freshwater tidal marsh along the Scheldt estuary (Belgium), covering oxygen, nutrients (N, P and Si), carbon, chlorophyll, suspended matter, chloride and sulfate. The role of seepage from the marsh was also investigated. A ranking between the parameters revealed that oxygenation was the strongest effect of the marsh on the estuarine water. Particulate parameters showed overall import. Export of dissolved silica (DSi) was more important than exchange of any other nutrient form. Export of DSi and import of total dissolved nitrogen (DIN) nevertheless contributed about equally to the increase of the Si:N ratio in the seepage water. The marsh had a counteracting effect on the long term trend of nutrient ratios in the estuary.  相似文献   

安微巢县下三叠统层序地层研究   总被引：10，自引：0，他引：10  

童金南 《地球学报》1997,18(2):215-219

安徽巢县马家山三叠系剖面其特殊的古构造和古理位置，在下扬子区域层序地层研究中处于重要位置。本文在沉积学、旋回分析和生态地层学等综合分析的基础上，结合下扬子区区域层序地层的发展特点，总结了该剖面下三叠统层序发育型式、发育特点及其演变过程，并以此为例论述了单剖面露头层序地层研究的基本方法。  相似文献   

基于荧光素和图像追踪技术的冻融循环作用下土体水汽迁移量测装置系统研究     

程博远  张玉芝  王天亮  温安  尹赵爱 《冰川冻土》2021,43(1):322-330

寒区高铁路基中粗颗粒填料水汽迁移可能是路基冻胀变形的来源,直观追踪冻融循环作用下土体水汽迁移过程,有助于研究水分迁移规律,为冻胀机理提供理论依据.基于此,提出采用荧光素示踪和图像处理技术方法,直观观测土体中水汽迁移的规律.首先开展荧光素示踪、蒸发试验及图像处理技术的研究,证明示踪剂可实现冻结锋面及外界液态水迁移的追踪;...  相似文献   

西太平洋暖池海域热含量场的变异及其影响   总被引：7，自引：2，他引：7       下载免费PDF全文

张启龙  翁学传  程明华 《海洋与湖沼》2003,34(4):389-396

基于 1 95 5— 1 999年间太平洋月平均海温资料 ,利用经验正交函数 (EOF)分解法 ,研究了西太平洋暖池海域 ( 1 2 0°E— 1 60°W ,1 8°N— 1 6°S)热含量场的时空变化 ,并分析了该海域东、西区热含量变化与南方涛动、副热带高压及ENSO的关系。结果表明 ,暖池海域热含量场主要包括年变化型、年际变化型和年代际变化型三个模态 ,其主要变化周期依次为 1 .0、3.6和 1 3.7年。相关和合成分析表明 ,暖池东、西区热含量的变化均与南方涛动、副热带高压和ENSO循环有十分密切的关系。  相似文献   

一个非线性连续培养模型极限环的位置     

朱乐敏  王元明  黄迅成  成安生 《广东海洋大学学报》2005,25(6):69-72

微生物培养是生化工程中的一个重要课题。研究了一个非线性连续微生物培养动力系统的极限环的相对位置。对带非常数产物系数的连续培养模型进行推广。模型中的极限环对应于发酵和生化培养中的非线性振荡,其相对位置对研究连续培养中振荡产生的时间和范围是有意义的。  相似文献   

A 640 kyr geomagnetic and palaeoclimatic record from Lake Baikal sediments     

Vadim A. Kravchinsky  Michael E. Evans  John A. Peck  Hideo Sakai  Mikhail A. Krainov  John W. King  Mikhail I. Kuzmin 《Geophysical Journal International》2007,170(1):101-116

Magnetic remanence vectors for 1737 samples from two ∼100 m cores of Lake Baikal sediments are reported along with complete magnetic susceptibility profiles obtained from a pass-through system. Chronological control is established by means of two independent correlations; first, by matching susceptibility variations to the oceanic oxygen isotope record and second, by matching the relative palaeointensity variations to the SINT-800 global reference curve. These both imply an average deposition rate of 15 cm kyr^–1 and a basal age of ∼640 ka. Spectral analysis reveals the presence of Milankovitch signals at ∼100 kyr (eccentricity), ∼41 kyr (obliquity) and ∼23 and ∼19 kyr (precession). Stable remanence vectors are almost all of normal polarity. The few exceptions comprise brief intervals of low and/or negative inclinations which probably represent geomagnetic excursions. However, these are far less numerous than the high sedimentation rate would lead one to expect. Furthermore, only four of them can be readily matched to the—still poorly understood—global pattern. These are the Laschamp, the Albuquerque, the Iceland Basin and perhaps the West Eifel excursions which occurred at ∼38 000, ∼146 000, at 180 000–190 000 and at 480 000–495 000 yr ago, respectively.  相似文献   

Carbon and oxygen isotopic variations in peritidal stromatolite cycles, Paleoproterozoic Kajrahat Limestone, Vindhyan basin of central India     

Santanu Banerjee  S.K. Bhattacharya  Subir Sarkar 《Journal of Asian Earth Sciences》2007,29(5-6):823-831

Variations of carbon and oxygen isotopic ratios in response to cyclical sea level fluctuations have been documented from a Paleoproterozoic peritidal stromatolite succession. The upper division of the Kajrahat Limestone, Vindhyan Supergroup of central India consists of several shallowing upward stromatolite cycles identified by regular and systematic changes in stromatolite size. Normally, larger stromatolites are followed upward in the succession by smaller stromatolites and microbial laminites that occupy the top of the cycle. Desiccation cracks are found in all the facies indicating subaerial exposure. We investigated the stable isotope compositional variations across nine complete stromatolite cycles showing frequent subaerial emergence. Carbon and oxygen isotopic values of the limestones, in general, are comparable to contemporary marine values available from earlier studies but show regular depletion in response to shallowing of the water level. The δ¹³C and δ¹⁸O values of the limestones vary within an individual stromatolite cycle; depleted values characterize the topmost part of the cycles. The isotope pattern is explained by micritic carbonate deposition in different sub environments of the shallow marine domain having different salinity and variable duration of exposure. These variations also probably caused the observed scatter in δ¹³C and δ¹⁸O values of supratidal microbial laminites.  相似文献   

Dolomite formation and biogeochemical cycles in the Phanerozoic   总被引：7，自引：0，他引：7  

Stephen J. Burns  Judith A. Mckenzie†  Crisogono Vasconcelos† 《Sedimentology》2000,47(S1):49-61

  相似文献