Effects of chemical ecological adjustment and control experiment on phytoplankton community in the Aoshan Bay     

Chen Bijuan  Zhao Jun  Xin Fuyan  Cui Yi  Guo Feng 《海洋学报(英文版)》2002,21(1):115-123

There is a low nutrient level in the Aoshan Bay. In June 1999, the chemical adjustmentand control experiment was made in the Aoshan Bay. Following tracts investigation was carried out before the experiment and on the 1st, 2nd, 4th, 5th, 6th and 45th day/after the experiment. While the variance of amount of phytoplankton, the replacement of superior species and the species composition of phytoplankton were researched. The results show that the amount of phytoplankton in the Aoshan Bay rises gradually after the experiment. Ceratium macroceros Cleve of pyrophyta was the dominant species before the experiment, its dominant index was 37.7％. Six days after the experiment, its dominant index dropped to 17.6％ . Meanwhile the dominant index of Asterionella japanics Cleve rose from 7.1％ to 39.2％ , it became the first dominant species. Forty-five days after the experiment, the amount of phytoplankton in the Aoshan Bay was 5.15 to 137.32 times more than that in 1997.  相似文献   

东山湾贝类养殖容量的估算   总被引：6，自引：0，他引：6  

卢振彬  杜琦  钱小明  方民杰  蔡清海  许翠娅 《台湾海峡》2001,20(4):462-470

以初级生产力为基础，应用营养动态模式和沿岸海域能流分析模型，估算东山湾贝类年生产量分别为269331t和295767t，平均282549t。扣除潮间带、潮下带和吊养区浮筏、随着基及延绳上附着的非养殖滤食性附着动物自然现存量35760t，贝类可养殖量为246789t。应用统计分析和逻辑斯谛种群增长模型估计贝类可养面积为11839hm^2，其中缢蛏635hm^2，石蛎1160hm^2,吊蛎1525hm^2，翡翠贻贝633hm^2，菲律宾蛤仔1154hm^2，扇贝698hm^2，江瑶248hm^2，泥蚶601hm^2，巴非蛤4151hm^2，凸壳肌蛤1034hm^2。1998年实际养殖面积和养殖产量分别为10581hm^2和220564t。尚有1258hm^2,26225t的扩大开发潜力。文中还讨论了合理布局和优化养殖结构问题。  相似文献   

水下智能潜器的神经网络运动控制   总被引：10，自引：4，他引：10  

彭良  卢迎春  万磊  孙俊岭 《海洋工程》1995,(2)

本文介绍一种基于神经网络的水下智能潜器的运动控制方法，该方法通过在线学习，融控制与滤波为一体。计算机仿真与水池实验验证表明，该方法的控制与滤波性能良好，对环境的学习与适应能力强。该方法事实上可用于一般动力系统的控制。  相似文献   

Processes Causing the Temporal Changes in Si/N Ratios of Nutrient Consumptions and Export Flux during the Spring Diatom Bloom     

Naoki?YoshieEmail author  Yasuhiro?Yamanaka 《Journal of Oceanography》2005,61(6):1059-1073

Two processes are generally explained as causes of temporal changes in the stoichiometric silicon/nitrogen (Si/N) ratios of sinking particles and of nutrient consumption in the surface water during the spring diatom bloom: (1) physiological changes of diatom under the stress of photosynthesis of diatom and (2) differences of regeneration between silicon and nitrogen. We investigated which process plays an important role in these changes using a one-dimensional ecosystem model that explicitly represents diatom and the other non-silicious phytoplankton. The model was applied to station A7 (41°30′ N, 145°30′ E) in the western North Pacific, where diatom regularly blooms in spring. Model simulations show that the Si/N ratios of the flux exported by the sinking particles at 100 m depth and of nutrient consumptions in the upper 100 m surface water have their maxima at the end of the spring diatom bloom, the values and timings of which are significantly different from each other. Analyses of the model results show that the differences of regeneration between silicon and nitrogen mainly cause the temporal changes of the Si/N ratios. On the other hand, the physiological changes of diatoms under stress can hardly cause these temporal changes, because the effect of the change in the diatom's uptake ratio of silicon to nitrogen is cancelled by that in its sinking rate.  相似文献   

A Zonal Pathway for NADW in the South Atlantic     

Nelson?G.?HoggEmail author  Andreas?M.?Thurnherr 《Journal of Oceanography》2005,61(3):493-507

Several large deployments of neutrally buoyant floats took place within the Antarctic Intermediate (AAIW), North Atlantic Deep Water (NADW), and the Antarctic Bottom Water (AABW) of the South Atlantic in the 1990s and a number of hydrographic sections were occupied as well. Here we use the spatially and temporally averaged velocities measured by these floats, combined with the hydrographic section data and various estimates of regional current transports from moored current meter arrays, to determine the circulation of the three major subthermocline water masses in a zonal strip across the South Atlantic between the latitudes of 19°S and 30°S. We concentrate on this region because the historical literature suggests that it is where the Deep Western Boundary Current containing NADW bifurcates. In support of this notion, we find that a net of about 5 Sv. of the 15–20 Sv that crosses 19°S does continue zonally eastward at least as far as the Mid-Atlantic Ridge. Once across the ridge it takes a circuit to the north along the ridge flanks before returning to the south in the eastern half of the Angola Basin. The data suggest that the NADW then continues on into the Indian Ocean. This scheme is discussed in the context of distributions of dissolved oxygen, silicate and salinity. In spite of the many float-years of data that were collected in the region a surprising result is that their impact on the computed solutions is quite modest. Although the focus is on the NADW we also discuss the circulation for the AAIW and AABW layers.  相似文献   

The fate of dumped sediments monitored by a high-resolution multibeam echosounder system,Weser Estuary,German Bight     

Claudia?WienbergEmail author  Jens?Dannenberg  Dierk?Hebbeln 《Geo-Marine Letters》2004,24(1):22-31

With the development of high-resolution multibeam echosounder systems (MBES) for surveying shallow-water areas a new tool is available to monitor rapid changes in seabed morphology as, e.g., caused by the dumping of dredge spoil in coastal waters. In this study, four data sets of repeated bathymetric surveys with a MBES were processed and analyzed. The data were collected in a 1.94-km² dumping site in the outer Weser Estuary (German Bight). Between June and December 1998, 2.6 million m³ of dredged sediment were deposited there. The bathymetric maps generated in the course of this study reveal features such as subaqueous dunes, scour holes, and mounds of dumped dredge spoil. The mean water depth decreased by about 1 m during the dumping period. Furthermore, difference grids showing changes in sediment volume allowed a calculation of the sediment budget for the monitored area. After a time period of only 5 months, 0.5 million m³ of the originally dumped 2.6 million m³ of dredge spoil had already been removed from the dumping site.  相似文献   

胶州湾沧口潮间带生态学研究   总被引：3，自引：0，他引：3  

庄启谦  崔可铎 《海洋科学集刊》1984,(22):79-96

我国从30年代开始就对潮间带生态学进行过研究，动物学界前辈张玺教授领导考察团，对胶州湾进行多次考察。50年代又对我国沿海有代表性的潮间带进行调查。在这个基础上，我们在1963年8月到1964年12月连续17个月，对胶州湾沧口泥沙滩进行了逐月的潮间带生态调查。主要目的是详细地了解我国北方海区潮间带泥沙底质生态类型的生物种类组成、垂直分布和数量变动，并对某些经济种类的生物学概况进行探讨。 将我们的调查材料与张玺早期的资料作一比较就可发现，虽然经过三十多年的时间，但胶州湾沧口泥沙滩潮间带的生物种类组成和分布基本上没有多大变化，它反映了污染前自然生态的面貌。本文详细阐明沧口泥沙滩潮间带的生态结构，表现沧口滩涂自然生态平衡的本底情况。 近十多年来，随着工业的发展，近岸工厂的污水及其他污染物排放入海，沧口泥沙滩潮间带的生态结构发生了变化，某些种类的分布下移，数量减少，某些种类已绝迹。近几年来，全国开展的海岸带和海涂综合调查需要有过去的本底资料进行对比，以便对现有资源量和将来可能发生的资源变动进行估计。为此，我们把以前的调查结果整理发表，为水产养殖、环境保护和海洋生态学研究提供必要的资料。  相似文献   

Size-Fractionated Primary Production Estimated by a Two-Phytoplankton Community Model Applicable to Ocean Color Remote Sensing   总被引：3，自引：0，他引：3  

Takahiko?KamedaEmail author  Joji?Ishizaka 《Journal of Oceanography》2005,61(4):663-672

In order to estimate primary production from ocean color satellite data using the Vertical Generalized Production Model (VGPM; Behrenfeld and Falkowski, 1997), we propose a two-phytoplankton community model. This model is based on the two assumptions that changes in chlorophyll concentration result from changes of large-sized phytoplankton abundance, and chlorophyll specific productivity of phytoplankton tends to be inversely proportional to phytoplankton size. Based on the analysis of primary production data, P _opt ^B , which was one parameter in the VGPM, was modeled as a function of sea surface temperature and sea surface chlorophyll concentration. The two-phytoplankton community model incorporated into the VGPM gave good estimates in a relatively high productive area. Size-fractionated primary production was estimated by the two-phytoplankton community model, and P _opt ^B of small-sized phytoplankton was 4.5 times that of large-sized phytoplankton. This result fell into the ranges observed during field studies.  相似文献   

Long-term Sensor Drift Found in Recovered Argo Profiling Floats   总被引：5，自引：0，他引：5  

Eitarou?OkaEmail author 《Journal of Oceanography》2005,61(4):775-781

We recovered three Argo profiling floats after 2 to 2.5 years of operation, and recalibrated their temperature, conductivity, and pressure sensors. The results demonstrate that these floats exhibited a significant drift in salinity of −0.0074 to −0.0125, primarily due to the conductivity sensor drift. Combined with the recalibration result for another previously recovered float, the indication is that the negative salinity drift increases nearly in proportion to the operating period of floats. The increasing rate is −0.0041 (±0.0015) year⁻¹, which yields a salinity drift of −0.016 (±0.006) for the expected float lifetime of four years. The present result suggests that reducing the float surfacing time would improve the accuracy of the salinity measurements.  相似文献   

长江口区枯、丰水期后底栖动物分布特点   总被引：2，自引：0，他引：2  

孙道元  徐凤山  崔玉珩  孙宾  王洪发 《海洋科学集刊》1992,(33):217-236

近几年来,对长江口底栖生物曾进行多次调查研究:1980-1981年进行了“中美海洋沉积作用联合研究”( Boesch等,1986;孙道元、董永庭,1986; Rhoads et al.，1985;Sun and Dong,1985);1982-1983年中国水产科学研究院东海水产研究所进行了“长江河口南岸污染对底栖生物的影响”的研究(戴国樑,1989):1985-1986年中国科学院海研究所进行了“长江口底栖生物及三峡工程对其影响的预测”的研究(刘瑞玉等,本集)。通过这些调查研究,基本掌握了长江口及其邻近水域底栖生物的概貌。 1988年4月和10月,作者又对长江口枯、丰水期后底栖动物的分布特点进行了调查研究。研究所用主要材料是在123°E以西,30°30′-32°00′N之间水域的35个取样站(图1)枯、丰水期后所获。海上取样每站以0.1㎡的表层采样器取样两次,通过0.5mm孔目的筛子冲洗后,样品在实验室内挑选、鉴定、称重和计数。  相似文献