Competition within the marine microalgae over the polar dark period in the Greenland Sea of high Arctic   总被引：2，自引：0，他引：2  

Zhang Qing  Rolf Gradinger  Zhou Qingsong 《海洋学报(英文版)》2003,22(2):233-242

Abstract-With the onset of winter, polar marine microalgae would have faced total darkness for aperiod of up to 6 months. A natural autumn community of Arctic sea ice microalgae was collected fordark survival experiments from the Greenland Sea during the ARKTIS-XI/2 Expedition of RV Po-larstern in October 1995. After a dark period of 161 days, species dominance in the algal assemblagehave changed from initially pennate diatoms to small phytoflagellates (<20μm). Over the entire darkperiod, the mean algal growth rate was-0.01 d~(-1). Nearly all diatom species had negative growthrates, while phytoflagellate abundance increased. Resting spore formation during the dark period was ob-served in less than 4.5% of all cells and only for dinoflagellates and the diatom Chaetoceros spp. We as-sume that facultative heterotrophy and energy storage are the main processes enabling survival during thedark Arctic winter. After an increase in light intensity, microalgal cells reacted with fast growth withindays. Phytoffa  相似文献   

A method to estimate the forces exerted by internal solitons on cylindrical piles   总被引：1，自引：0，他引：1  

Shuqun Cai  Xiaomin Long  Zijun Gan 《Ocean Engineering》2003,30(5):673-689

Internal soliton is the large amplitude wave existing in the pycnocline, induced by internal tide in the condition of special bottom topography. During its propagation process, the induced disturbance can bring about strong convergence of sea water and sudden strong current (wave-induced-current), which can cause severe threat to the ocean engineering structures, such as oil drilling platform and pipeline. In this paper, Morison’s empirical method, modal separation and regression analyses are introduced to estimate the forces and torques exerted by internal soliton on cylindrical piles. As an example, a limited set of observational data recording a passage of the internal soliton near Dongsha Islands is used to estimate the horizontal velocity and its acceleration in a vertical section for computing the force and torque on a supposed pile, and the estimation results are reasonable. It is shown that, the higher number of the modes retained in the calculation, the better the estimation of velocity profile fits the observational one. A better overall approximation to the real solution can be reached if there are more observational current data acquired in a whole vertical profile.  相似文献   

基于EOF分析对南海西北海域水体光谱特性的研究   总被引：1，自引：0，他引：1  

付东洋  黄宇业  刘大召  廖珊  余果  张小龙 《海洋学报(英文版)》2020,39(7):107-114

This study presents an analysis of the spectral characteristics of remote sensing reflectance(R_(rs)) in northwestern South China Sea based on the in situ optical and water quality data for August 2018.R_(rs)was initially divided into four classes,classes A to D,using the max-classification algorithm,and the spectral properties of whole R_(rs) were characterized using the empirical orthogonal function(EOF) analysis.Subsequently,the dominant factors in each EOF mode were determined.The results indicated that more than 95% of the variances of R_(rs) are partly driven by the back-scattering characteristics of the suspended matter.The initial two EOF modes were well correlated with the total suspended matter and back-scattering coefficient.Furthermore,the first EOF modes of the four classes of R_(rs)(A-D R_(rs)-EOF_1) significantly contributed to the total variances of each R_(rs) class.In addition,the correlation coefficients between the amplitude factors of class A-D R_(rs)-EOF_1 and the variances of the relevant water quality and optical parameters were better than those of the unclassified ones.The spectral shape of class AR_(rs)-EOF_1 was governed by the absorption characteristic of chlorophyll a and colored dissolved organic matter(CDOM).The spectral shape of class B R_(rs)-EOF_1 was governed by the absorption characteristic of CDOM since it exhibited a high correlation with the absorption coefficient of CDOM(a_g(λ)),whereas the spectral shape of class C R_(rs)-EOF_1 was governed by the back-scattering characteristics but not affected by the suspended matter.The spectral shape of class D R_(rs)-EOF_1 exhibited a relatively good correlation with all the water quality parameters,which played a significant role in deciding its spectral shape.  相似文献   

The Bering Sea—A dynamic food web perspective     

Kerim Aydin  Franz Mueter   《Deep Sea Research Part II: Topical Studies in Oceanography》2007,54(23-26):2501

The Bering Sea is a high-latitude, semi-enclosed sea that supports extensive fish, seabird, marine mammal, and invertebrate populations and some of the world's most productive fisheries. The region consists of several distinct biomes that have undergone wide-scale population variation, in part due to fisheries, but also in part due to the effects of interannual and decadal-scale climatic variation. While recent decades of ocean observation have highlighted possible links between climate and species fluctuations, mechanisms linking climate and population fluctuations are only beginning to be understood. Here, we examine the food webs of Bering Sea ecosystems with particular reference to some key shifts in widely distributed, abundant fish populations and their links with climate variation. Both climate variability and fisheries have substantially altered the Bering Sea ecosystem in the past, but their relative importance in shaping the current ecosystem state remains uncertain.  相似文献   

Trichodesmium erythraeum (Ehrenberg) bloom along the southwest coast of India (Arabian Sea) and its impact on trace metal concentrations in seawater     

Anoop A. Krishnan  P.K. Krishnakumar  M. Rajagopalan 《Estuarine, Coastal and Shelf Science》2007,71(3-4):641-646

The incidence of a large scale Trichodesmium erythraeum bloom along the southwest coast of India (Arabian Sea) observed in May 2005 is reported. Around 4802 filaments of T. erythraeum ml⁻¹ seawater was observed and a colony consisted of 3.6 × 10⁵ cells. The bloom was predominant off Suratkal (12° 59′N and 74° 31′E) with a depth of about 47 m, covering an area of 7 km in length and 2 km width. The concentrations of Zinc, Cadmium, Lead, Copper, Nickel and Cobalt were determined in samples collected from the bloom and non-bloom sites using stripping voltammetry. The observed hydrographical and meteorological parameters were found to be favorable for the bloom. The concentrations of Zinc, Cadmium and Nickel were found to be higher at bloom stations, while the concentrations of Lead, Copper and Cobalt were found to be very low at bloom stations. Elevated concentrations of Cadmium and Cobalt were observed at Valappad mainly due to the decomposition of detrital material produced in the bloom. Statistically significant differences (P > 0.01) in metal concentrations between the bloom and non-bloom stations were not observed except for Copper. Metals such as Lead, Copper and Cobalt were removed from the seawater at all places where bloom was observed. Cadmium was found to be slowly released during the decaying process of the bloom.  相似文献   

Organic matter origin and distribution in suspended particulate materials and surficial sediments from the western Adriatic Sea (Italy)   总被引：5，自引：2，他引：5  

T. Tesi  S. Miserocchi  M.A. Goi  L. Langone  A. Boldrin  M. Turchetto 《Estuarine, Coastal and Shelf Science》2007,73(3-4):431-446

In this study, organic carbon (OC), total nitrogen (TN), stable carbon isotopic (δ¹³C_OC) and CuO reaction product compositions were used to identify the sources of organic matter (OM) and to quantify the relative importance of allochthonous and autochthonous contributions to the western Adriatic Sea, Italy. Suspended particulate material (195 samples) and surficial sediments (0–1 cm, 70 samples) from shallow cross-shelf transects were collected in February and May 2003, respectively. Vertical water column profiles were acquired along the same transects. Data include depth, potential temperature, salinity, density and chlorophyll fluorimetry.Along the western Adriatic shelf in the near-shore region, the phytoplankton growth was influenced by dynamics of the buoyant plumes from the Po and Appennine rivers. A small amount of very fine terrigenous material remained suspended within the coastal current and was exported southward along the shelf to the slope. High variability in the bulk composition was detected in the Po prodelta surficial sediments, whereas the western Adriatic shelf, although a larger area, exhibited a narrower range of values.A significant decoupling was observed between suspended particles in the water column and surficial deposits. The organic material collected in the water column was compositionally heterogeneous, with contributions from marine phytoplankton, riverine–estuarine phytoplankton and soil-derived OM. Frequent physical reworking of surficial sediments likely leads to the efficient oxidation of marine OC, resulting in the observed accumulation and preservation of refractory soil-derived OC delivered by the Po and Appennine rivers.  相似文献   

Application of LICOM to the numerical study of the water exchangebetween the South China Sea and its adjacent oceans   总被引：8，自引：1，他引：8  

CAI Shuqun  LIU Hailong  LI Wei  LONG Xiaomin 《海洋学报(英文版)》2005,24(4):10-19

1 IntroductionThe South China Sea (SCS) is the largestmarginal sea in the western Pacific (see Fig. 1). It con-nects with the SCS through the Taiwan Strait, with thePacific through the Luzon Strait, with the Sulu Seathrough the Mindoro and Balabac Straits and with theJava Sea and Andaman Sea through the Sunda Shelf(For convenience, here we refer to the section at 1.5°N,Fig. 2). It is shown that the seasonal SCS circulation ismostly affected by the summer/winter monsoon, andthe no…  相似文献   

Growth and gonad production of the sea urchin Hemicentrotus pulcherrimus in the fucoid bed and algal turf in northern Japan     

Yukio Agatsuma  Nobuyasu Nakabayashi  Nobuaki Miura  & Kazuya Taniguchi 《Marine Ecology》2005,26(2):100-109

To clarify the differences in the growth and gonad size of the sea urchin Hemicentrotus pulcherrimus among algal sere, the study was conducted in June and July, and September 1998 at three fucoid beds in Oga and at three algal turfs in Hachimori, Akita Prefecture in northern Japan. The most rapid growth was observed in a large perennial fucoid bed at the climax stage. Growth in a small perennial Chondrus ocellatus‐dominated bed in algal turfs in the seral stage was then high. The slowest growth was observed in the small perennial Dictyopteris divaricata‐ and Laurencia spp.‐dominated beds which are known to possess chemicals which act as feeding deterrents against the sea urchins. The gonad index (gonad wet weight × 100/body wet weight) at a fucoid bed was high where standing crops exceeded 3 kg·m^?2. The gonad index in the Laurencia bed was lower than those at fucoid beds. These results suggest that growth and gonad production are affected by algal sere and differ among species of small perennial algae in the seral stage with or without chemical defense.  相似文献   

台湾海峡纽形动物初报   总被引：1，自引：1，他引：1  

孙世春 《海洋科学》1995,19(5):45-48

首次报道台湾海峡产的纽形动物，包括沙栖原细首纽虫、浮游拟脑纽虫、椒状岩田纽虫、中华平裂纽虫和马顿氏潘丁纽虫，共５种。除椒状岩田纽虫在琉球群岛有报道外，均为东海新记录。  相似文献   

Trends in age-composition, growth and reproductive parameters of Barents Sea harp seals, Phoca groenlandica     

Kjellqwist  Sten Anders; Haug  Tore; Oritsland  Torger 《ICES Journal of Marine Science》1995,52(2):197-208

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