The Estimation of Secondary Production of the Marine Bivalve Spisula subtruncata (DA COSTA) in the Area of the Po River Delta     

Romano  Ambrogi Anna Occhipinti  Ambrogi 《Marine Ecology》1985,6(3):239-250

Abstract. The secondary production of Spisula subtruncata (somatic production) is calculated in the framework of a benthic monitoring study in a coastal area. The temporal trends of density, biomass and growth increments are examined in the three year-classes present. These are compared to certain physical and chemical parameters.  相似文献   

Egg production of Calanus finmarchicus—A basin-scale study     

Erling K. Stenevik  Webjrn Melle  Eilif Gaard  Astthor Gislason  Cecilie T.. Broms  Irina Prokopchuk  Bjrnar Ellertsen 《Deep Sea Research Part II: Topical Studies in Oceanography》2007,54(23-26):2672

Egg production of Calanus finmarchicus was studied during joint basin-scale surveys in April–June 2003 in the Norwegian Sea. Surveys covered the whole Norwegian Sea and were conducted from Norwegian, Icelandic and Faroese research vessels. Stations were classified as being in pre-bloom, bloom or post-bloom phase according to levels of chlorophyll a and nitrate. Individual egg production rates and population egg production rates were calculated and compared between areas. Both individual egg production rates (eggs female⁻¹ day⁻¹) and population egg production rates (eggs m⁻² day⁻¹) were significantly higher in bloom areas compared with pre-bloom and post-bloom areas. However, when integrated over an estimated duration of the three phases, the time-integrated egg production (eggs m⁻²) in most years was highest in the pre-bloom phase, and this was explained by the longer duration of this phase compared with the two other phases.  相似文献   

The role of marine spatial planning in sea use management: The Belgian case   总被引：1，自引：0，他引：1  

F. Douvere  F. Maes  A. Vanhulle  J. Schrijvers 《Marine Policy》2007

The expansion of offshore activities and the increasing need to meet international and national commitments to biodiversity conservation have led to an enhanced interest in marine spatial planning (MSP) as a tool for sea use management. Several European countries, on their own initiative or driven by European legislation and policy, have taken global leadership in implementing MSP. This article will discuss the Belgian experiences with MSP. It will give a short historical overview based on legal developments and review the implementation process of a ‘Master Plan’ as a spatial management policy for the Belgian Part of the North Sea. Additionally, this article will reflect on the research that has been done in Belgium to apply a land-use planning approach to the marine environment. The MSP process in Belgium shows that a spatial approach to sea use management is possible despite the lack of a legal zoning framework. However, it concludes that a legal basis for MSP, in addition to the current permit system, would provide a more strategic and integrated framework for ecosystem-based, sea use management.  相似文献   

Circulation in the Gulf of Aqaba (Red Sea) during winter—spring     

Riyad Manasrah  H. Uli Lass  Wolfgang Fennel 《Journal of Oceanography》2006,62(2):219-225

This study is devoted to oceanographic features of the semi-enclosed Gulf of Aqaba, Red Sea. The data were recorded in winter—spring 1999 on the R/V Meteor cruise leg 44/2. Temperature and salinity profiles were measured at six positions (I—VI). The shipboard NarrowBand Acoustic Doppler Current Profiler (NB ADCP) 150 kHz continuously recorded current profiles down to 350 m en route. The research revealed that the current near the Strait of Tiran front (position VI) represents a semidiurnal signal of an internal tide wave (∼12 h period; 0.2 ms⁻¹ amplitude) that might be generated by the barotropic tide at the sill of the Strait. A sequence of cyclonic and anticyclonic eddy pairs is found along the axis of the Gulf of Aqaba during winter-spring seasons. These sub-mesoscale signals are dominant above the main thermocline and might be caused by wind forcing and the narrowness of the Gulf; it might remain in other seasons with different dimensions in relation to the depth of thermocline. The total diameter of each pair was twice the baroclinic Rossby radius (R ≈ 10 km). A single anti-cyclonic eddy was observed in the upper 300 m in the northern tip of the Gulf with a diameter of about 5–8 km.  相似文献   

南黄海灾害地质因素及分区     

陆凯  宋召军 《海洋地质前沿》2005,21(7):9-12

尝试性地将南黄海灾害地质因素分为4大类。同时参考地貌沉积界线和其他因素将南黄海分成4个灾害地质区：即海岸带、苏北浅滩、海州湾和南黄海东部灾害地质区，并时各灾害地质区进行了定性评价，苏北浅滩灾害地质区是研究区内灾害地质环境最不稳定的区域。  相似文献   

南海天然气水合物的形成和分布   总被引：17，自引：0，他引：17  

姚伯初 《海洋地质与第四纪地质》2005,25(2):81-90

从物理海洋、古气候、沉积环境和构造环境分析入手，研究了南海天然气水合物的形成条件。研究结果表明，在整个南海海域，天然气水合物生成的条件是存在差别的。南海，东北部，在氧同位素2、4、6期，由于菲律宾海的高盐度海水的注入，使这里的生物生产率特别高，陆坡上沉积了丰富的有机物质，加上此期间该处的沉积速率高，为天然气水合物的生成提供了物质条件；另外，自中新世末以来，由于菲律宾海板块与欧亚板块在台湾地区发生碰撞，对南海北部产生北西向挤压，加快了流体在沉积物中的活动，为天然气水合物的生成提供了良好的构造环境。因此认为南海东北部陆坡应是南海天然气水合物最丰富的地区。  相似文献   

渤海三维海洋温度和海流数值预报   总被引：3，自引：2，他引：3  

刘钦政  张建华  刘煜  王旭  李燕  白珊  吴辉碇 《海洋预报》2005,22(Z1):27-34

"十·五"期间,我国开展了三维海洋温度和海流数值预报的业务化研究工作.经过3年的努力,渤海三维海洋温度和海流数值预报系统研制完成,并于2003年10月,开始试预报.本文对该预报系统以及运行情况进行了介绍,并分析了所存在的问题和发展方向.  相似文献   

Rock magnetic records of the sediments of the eastern Arabian Sea: Evidence for late Quaternary climatic change     

A. Anil Kumar  V. Purnachandra Rao  S.K. Patil  Pratima M. Kessarkar  M. Thamban   《Marine Geology》2005,220(1-4):59-82

Rock-magnetic measurements along with grain size, acid-insoluble residue (AIR), organic carbon (OC), CaCO₃ and δ¹⁸O of the planktonic foraminifers of the sediments were determined for 15 gravity cores recovered from the western continental margin of India. Magnetic susceptibility (MS) values in the surficial sediments reflect the land-derived input and, in general, are the highest in terrigenous sediment-dominated sections of the cores off Saurashtra–Ratnagiri, followed by the sediments off Indus–Gulf of Kachchh and then Mangalore–Cape Comorin.

The down-core variations in mineral magnetic parameters reveal that the glacial sediments off the Indus are characterized by low MS values/S-ratios associated with high AIR-content, low OC/CaCO₃ contents and relatively high δ¹⁸O values, while those off SW India are characterized by low MS values/high S-ratio% associated with low AIR content, and relatively high OC, CaCO₃ and δ¹⁸O values. Conversely, the Early Holocene sediments of all cores are characterized by high MS values/S-ratio% associated with high AIR content, low OC, CaCO₃ contents and gradually decreased δ¹⁸O values. These results imply that during the Last Glacial Maximum (LGM), the cores off northwestern India received abundant continental supply leading to the predominance of eolian/fluvial sedimentation. In the SW region the influence of hinterland flux is less evident during this period, but convective mixing associated with the NE monsoon resulted in increased productivity. During the early Holocene intense SW monsoon conditions resulted in high precipitation on land, which in turn contributed increased AIR content/MS values in the continental margin sediments. A shallow water core off Kochi further suggests that the intense SW monsoon conditions prevailed until about 5 ka. The late Holocene organic-rich sediments of the SW margin of India were, however, subjected to early diagenesis at different intervals in the cores. Therefore, caution is needed when interpreting regional climatic change from down-core changes in sediment magnetic properties.  相似文献   

Late Quaternary Seasonal Sea-Ice History of the Northeastern Japan Sea     

Ken Ikehara 《Journal of Oceanography》2003,59(5):585-593

The Late Quaternary sea-ice history of the northeastern Japan Sea is discussed on the basis of the occurrence of dropstones and ice-rafted debris (IRD) in fine sediment cores. IRD was found in all strata except those from the Holocene and oxygen isotope stage 5.5. The largest expansion of sea ice was recognized at the last glacial maximum (LGM; oxygen isotope stage 2), when the southern margin of seasonal sea ice was probably located in the vicinity of the Matsumae Plateau. The margin might occasionally have expanded further southward to off the Oga Peninsula. Sea ice expanded southward from mid-stage 5 to the LGM in response to global cooling, but with much fluctuation. Sea ice remained during deglaciation until around 10 ka, but after 10 ka it retreated northward rapidly in response to global warming and changes in surface water conditions. Greater fluctuations in IRD were found in core GH95-1208 collected from off Rumoi, Hokkaido, Japan. More IRD was found in sediments from late stage 3, late stage 5, and early stage 6. The fluctuations were not concordant with global climate changes (based on the standard oxygen isotope curve), and may have been controlled by regional climate factors such as the strength of the winter monsoon, which is related in turn to high-latitude atmospheric circulation. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Multi-decadal synthesis of benthic–pelagic coupling in the western arctic: Role of cross-shelf advective processes     

Kenneth H. Dunton  Jonathan L. Goodall  Susan V. Schonberg  Jacqueline M. Grebmeier  David R. Maidment 《Deep Sea Research Part II: Topical Studies in Oceanography》2005,52(24-26):3462

Using geographic information systems (GIS) software and geostatistical techniques, we utilized three decades of water-column chlorophyll a data to examine the relative importance of autochthonous versus allochthonous sources of reduced carbon to benthic communities that occur from the northern Bering to the eastern Beaufort Sea shelf. Spatial trend analyses revealed areas of high benthic biomass (>300 g m⁻²) and chlorophyll (>150 mg m⁻²) on both the southern and northern Chukchi shelf; both areas are known as depositional centers for reduced organic matter that originates on the Bering Sea shelf and is advected northward in Anadyr and Bering shelf water masses. We found a significant correlation between biomass and chlorophyll a in the Chukchi Sea, reflective of the strong benthic–pelagic coupling in a system that is utilized heavily by benthic-feeding marine mammals. In contrast, there was no significant correlation between biomass and chlorophyll in the Beaufort Sea, which by comparison, is considerably less productive (biomass and chlorophyll, <75 g m⁻² and <50 mg m⁻², respectively). One notable exception is an area of relatively high biomass (50–100 g m⁻²) and chlorophyll (80 mg m⁻²) near Barter Island in the eastern Beaufort Sea. Compared to other adjacent areas in the Beaufort Sea, the chlorophyll values in the vicinity of Barter Island were considerably higher and likely reflect a long-hypothesized upwelling in that area and close coupling between the benthos and autochthonous production. In the Bering Sea, a drop in benthic biomass in 1994 compared with previous measurements (1974–1993) may support earlier observations that document a decline in biomass that began between the 1980s and 1990s in the Chirikov Basin and south of St. Lawrence Island. The results of this study indicate that the benthos is an excellent long-term indicator of both local and physical advective processes. In addition, this work provides further evidence that secondary production on arctic shelves can be significantly augmented by reduced carbon advected from highly productive adjacent shelves.  相似文献