Temporal change of clustered distribution of planktonic ciliates in Toyama Bay in summers of 1989 and 1990     

Toshikazu Suzuki  Akira Taniguchi 《Journal of Oceanography》1997,53(1):35-40

Temporal change of clustered distribution in vertical profiles of three nutritional groups of planktonic ciliates, e.g. heterotrophic naked ciliates, mixotrophic naked ciliates and heterotrophic loricated ciliates, was investigated by following a drifting buoy in Toyama Bay on the Japan Sea coast of central Japan in summers of 1989 and 1990. Clustered distribution, represented as the mode of population density in the vertical plane, occurred mainly in the oligotrophic upper layer (0–50 m depth) above the subsurface chlorophyll-a maximum layer. Its clustered degree was stronger when the mode of population density in the vertical plane was formed at shallower depth, while its longevity was shorter as mentioned above. Vertical distribution of ciliates during summer in Toyama Bay is characterized by ephemeral clustered distribution, or in other wards, by rapid alternations of appearance and disappearance of the clustered distribution.  相似文献   

Estimating mortality rates from tag recoveries: incorporating over-dispersion, correlation, and change points     

Kitada  Shuichi; Hiramatsu  Kazuhiko; Kishino  Hirohisa 《ICES Journal of Marine Science》1994,51(3):241-251

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Mid-Holocene emergence of southern Tunisian coasts     

Christophe Morhange  Paolo Antonio Pirazzoli   《Marine Geology》2005,220(1-4):205-213

We present new sea-level data from the coasts of southern Tunisia, between the Gulf of Gabès and the Libyan border. The work tests, previously, published evidence on Holocene shorelines, and confirmed that a distinct emergence has occurred in this area during this time. The emergence peak lies at least 186 ± 11 cm above present and is inferred from: (1) AMS radiocarbon dates of subtidal vermetids and boring shells collected in growth position, and (2) careful assessment of tidal heights. Maximum emergence took place between about 6000 and 5000 ¹⁴C years BP; it cannot be ascribed to tectonics and is probably related to post-glacial hydro-isostatic effects. It challenges the inference of a 3-m global sea-level rise since 6000 years BP due to residual Antarctic melting.  相似文献   

Evidence of temporal genetic change in wild Atlantic salmon, Salmo salar L., populations affected by farm escapees     

Skaala  Oystein; Wennevik  Vidar; Glover  Kevin A. 《ICES Journal of Marine Science》2006,63(7):1224-1233

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海洋岛海域水温异常波动与养殖栉孔扇贝死亡的关系   总被引：2，自引：0，他引：2  

周玮  薛真福  王有君  贺先钦  林祥辉  王庆成  刘兴盛  孙景伟 《海洋湖沼通报》1992,(4)

本文对海洋岛海域水温异常波动,与该海域养殖栉孔扇贝大批死亡的关系,进行了研究。首先,总结了几年来海洋岛海域养殖栉孔扇贝死亡的特征。其次,结合水温观测数据分析了水温异常波动与栉孔扇贝大批死亡的关系。得出的结论是:大幅度、跳跃型水温异常波动是导致扇贝死亡主要原因。最后,通过生物试验证实了上述观点。  相似文献   

Physical and anthropogenic effects on observed long-term nutrient changes in the Irish Sea     

G. L. Evans  P. J. le B. Williams  E. G. Mitchelson-Jacob 《Estuarine, Coastal and Shelf Science》2003,57(5-6):1159-1168

The trend in Irish Sea nutrient concentrations over the last four decades has been considered to reflect changes in anthropogenic loading. Comparison of a long-term database for the Menai Strait, North Wales, with an established historic data set for the Cypris station, Isle of Man, indicates that climate also has a significant influence on observations of nutrient concentrations. Data are presented detailing long-term shifts in nitrate, phosphate and silicate measurements since the 1960s at these two fixed sampling sites in the Irish Sea. Broad systematic changes observed in all three nutrients over the decades show a rise from the 1960s through to the 1980s, followed generally by an overall decline in the 1990s. Decadal-scale salinity changes occur in the opposite sense to nutrient changes. Anthropogenic inputs from freshwater cannot fully account for observed nutrient trends, neither is there evidence for shifts in nutrient concentrations in oceanic waters over the past four decades. Climatically forced movement in the geographical position of the freshwater/seawater mixing zone over a decadal time scale could, however, give rise to the observed shifts in nutrient concentration and salinity. This cannot alter nutrient concentration and salinity per se, but causes the measurements taken at fixed sampling sites to fluctuate inversely over this time scale. It is concluded that there is complex interplay between anthropogenic loading and climate affecting the distribution of nutrients in the Irish Sea.  相似文献   

Spatial variability in the partial pressures of CO₂ in the northern Bering and Chukchi seas   总被引：2，自引：0，他引：2  

Liqi Chen  Zhongyong Gao   《Deep Sea Research Part II: Topical Studies in Oceanography》2007,54(23-26):2619

In the summers of 1999 and 2003, the 1st and 2nd Chinese National Arctic Research Expeditions measured the partial pressure of CO₂ in the air and surface waters (pCO₂) of the Bering Sea and the western Arctic Ocean. The lowest pCO₂ values were found in continental shelf waters, increased values over the Bering Sea shelf slope, and the highest values in the waters of the Bering Abyssal Plain (BAP) and the Canadian Basin. These differences arise from a combination of various source waters, biological uptake, and seasonal warming. The Chukchi Sea was found to be a carbon dioxide sink, a result of the increased open water due to rapid sea-ice melting, high primary production over the shelf and in marginal ice zones (MIZ), and transport of low pCO₂ waters from the Bering Sea. As a consequence of differences in inflow water masses, relatively low pCO₂ concentrations occurred in the Anadyr waters that dominate the western Bering Strait, and relatively high values in the waters of the Alaskan Coastal Current (ACC) in the eastern strait. The generally lower pCO₂ values found in mid-August compared to at the end of July in the Bering Strait region (66–69°N) are attributed to the presence of phytoplankton blooms. In August, higher pCO₂ than in July between 68.5 and 69°N along 169°W was associated with higher sea-surface temperatures (SST), possibly as an influence of the ACC. In August in the MIZ, pCO₂ was observed to increase along with the temperature, indicating that SST plays an important role when the pack ice melts and recedes.  相似文献   

厦门东海域定置网渔获鱼类种类组成及其季节变化   总被引：7，自引：1，他引：7  

黄良敏  张雅芝  姚舒栓 《台湾海峡》2006,25(4):509-520

2003年7月～2004年6月对厦门东部海域的定置网渔获鱼类进行采样分析．结果表明厦门东海域至少有鱼类242种，隶属于19个目81科145属，主要是沿岸近底层和底栖的小型鱼类．以鲈形目种类最多，共计127种，占总数的52．5％、经济种类有116种．主要优势种有：青鳞小沙丁鱼、孔鳞小沙丁鱼、斑鲦、马拉邦虫鳗、裸鳍虫鳗、中华须鳗、前鳞鲻、眶棘双边鱼、多鳞鳝、皮氏叫姑鱼、短棘银鲈、列牙垒幸4、黄斑蓝子鱼、褐蓝子鱼、锯塘鳢、锻虎鱼类、褐菖鲇、绿鳍鱼、鳄鲡、卵鳎、中华单角鲍等．渔获种类在秋季及冬初最多，夏季较多，而冬末和春初最少．渔获种类的季节变化比较明显，与海洋表层水温变化有关，种类的月更替率比较高．  相似文献   

湄洲湾泥沙活动及海底冲淤变化   总被引：1，自引：0，他引：1  

郭允谋  杨顺良 《台湾海峡》1993,12(1):8-15

湄洲湾沙源少,海水含沙量低,平均值10～20g/m~3。冬季受东北季风及浙闽沿岸流影响,湾口含沙量高,达到34g/m~3;夏季受径流影响,湾内含沙量相对偏高,达到16g/m~3。泥沙的运移趋势:主航道基本朝外,两侧朝里。受强潮流作用,深槽及水下潮流冲沟受到冲刷,斜坡及潮坪略有淤积。  相似文献   

Use of Continuous Plankton Recorder information in support of marine management: applications in fisheries, environmental protection, and in the study of ecosystem response to environmental change   总被引：2，自引：0，他引：2  

K. M. Brander  R. R. Dickson  M. Edwards 《Progress in Oceanography》2003,58(2-4):175

The Continuous Plankton Recorder (CPR) survey was conceived from the outset as a programme of applied research designed to assist the fishing industry. Its survival and continuing vigour after 70 years is a testament to its utility, which has been achieved in spite of great changes in our understanding of the marine environment and in our concerns over how to manage it. The CPR has been superseded in several respects by other technologies, such as acoustics and remote sensing, but it continues to provide unrivalled seasonal and geographic information about a wide range of zooplankton and phytoplankton taxa. The value of this coverage increases with time and provides the basis for placing recent observations into the context of long-term, large-scale variability and thus suggesting what the causes are likely to be. Information from the CPR is used extensively in judging environmental impacts and producing quality status reports (QSR); it has shown the distributions of fish stocks, which had not previously been exploited; it has pointed to the extent of ungrazed phytoplankton production in the North Atlantic, which was a vital element in establishing the importance of carbon sequestration by phytoplankton.The CPR continues to be the principal source of large-scale, long-term information about the plankton ecosystem of the North Atlantic. It has recently provided extensive information about the biodiversity of the plankton and about the distribution of introduced species. It serves as a valuable example for the design of future monitoring of the marine environment and it has been essential to the design and implementation of most North Atlantic plankton research.  相似文献