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21.
22.
I\rnooUcrIoxThe drpdric fish species cor-npositlon is an imPOrtant element 1n the study of fish ecologyand plays an important guiding role ln fishery preduction and roouLrces rnanagement. Lin(l988) and Zhang (1994 and l995) have studied the simi1drities of mpulation COtwsition ofame s1ngle species of different yea-rs including hairtail Trichuras haumee and yellDw cndertwinena cmi. But no rePOrt is available on the discridrination of the sidrildrities amongmuLlt1ple sPecies composition of… 相似文献
23.
Atmospherically-promoted photosynthetic activity in a well-mixed ecosystem: Significance of wet deposition events of nitrogen compounds 总被引:1,自引:0,他引:1
C. Boulart P. Flament V. Gentilhomme K. Deboudt C. Migon F. Lizon M. Schapira A. Lefebvre 《Estuarine, Coastal and Shelf Science》2006,69(3-4):449
Wet atmospheric deposition of dissolved N, P and Si species is studied in well-mixed coastal ecosystem to evaluate its potential to stimulate photosynthetic activities in nutrient-depleted conditions. Our results show that, during spring, seawater is greatly depleted in major nutrients: Dissolved Inorganic Nitrogen (DIN), Dissolved Inorganic Phosphorus (DIP) and Silicic acid (Si), in parallel with an increase of phytoplanktonic biomass. In spring (March–May) and summer (June–September), wet atmospheric deposition is the predominant source (>60%, relative to riverine contribution) for nitrates and ammonium inputs to this N-limited coastal ecosystem. During winter (October–February), riverine inputs of DIN predominate (>80%) and are annually the most important source of DIP (>90%). This situation allows us to calculate the possibility for a significant contribution to primary production in May 2003, from atmospheric deposition (total input for DIN ≈300 kg km−2 month−1). Based on usual Redfield ratios and assuming that all of the atmospheric-derived N (AD-N) in rainwater is bioavailable for phytoplankton growth, we can estimate new production due to AD-N of 950 mg C m−2 month−1, during this period of depletion in the water column. During the same episode (May 2003), photosynthetic activity rate, considered as gross primary production, was estimated to approximately 30 300 mg C m−2 month−1. Calculation indicates that new photosynthetic activity due to wet atmospheric inputs of nitrogen could be up to 3%. 相似文献
24.
Effects of cold eddy on phytoplankton production and assemblages in Luzon strait bordering the South China Sea 总被引:6,自引:0,他引:6
Yuh-Ling Lee Chen Houng-Yung Chen I. -I. Lin Ming-An Lee Jeng Chang 《Journal of Oceanography》2007,63(4):671-683
The biochemical effects of a cold-core eddy that was shed from the Kuroshio Current at the Luzon Strait bordering the South
China Sea (SCS) were studied in late spring, a relatively unproductive season in the SCS. The extent of the eddy was determined
by time-series images of SeaWiFS ocean color, AVHRR sea surface temperature, and TOPEX/Jason-1 sea surface height anomaly.
Nutrient budgets, nitrate-based new production, primary production, and phytoplankton assemblages were compared between the
eddy and its surrounding Kuroshio and SCS waters. The enhanced productivity in the eddy was comparable to wintertime productivity
in the SCS basin, which is supported by upwelled subsurface nitrate under the prevailing Northeastern Monsoon. There were
more Synechococcus, pico-eucaryotes, and diatoms, but less Trichodesmium in the surface water inside the eddy than outside. Prochlorococcus and Richelia intracellularis showed no spatial differences. Water column-integrated primary production (IPP) inside the eddy was 2–3 times that outside
the eddy in the SCS (1.09 vs. 0.59 g C m−2d−1), as was nitrate-based new production (INP) (0.67 vs. 0.25 g C m−2d−1). INP in the eddy was 6 times that in the Kuroshio (0.12 g C m−2d−1). IPP and INP in the eddy were higher than the maximum production values ever measured in the SCS basin. Surface chlorophyll
a concentration (0.40 mg m−3) in the eddy equaled the maximum concentration registered for the SCS basin and was higher than the wintertime average (0.29
± 0.04 mg m−3). INP was 3.5 times as great and IPP was doubled in the eddy compared to the wintertime SCS basin. As cold core eddies form
intermittently all year round as the Kuroshio invades the SCS, their effects on phytoplankton productivity and assemblages
are likely to have important influences on the biogeochemical cycle of the region. 相似文献
25.
Jörn Thiede Stephanie Pfirman Hans-Werner Schenke Wolfgang Reil 《Marine Geophysical Researches》1990,12(3):197-214
The sea floor of Fram Strait, the over 2500 m deep passage between the Arctic Ocean and the Norwegian-Greenland Sea, is part of a complex transform zone between the Knipovich mid-oceanic ridge of the Norwegian-Greenland Sea and the Nansen-Gakkel Ridge of the Arctic Ocean. Because linear magnetic anomalies formed by sea-floor spreading have not been found, the precise location of the boundary between the Eurasian and the North American plate is unknown in this region. Systematic surveying of Fram Strait with SEABEAM and high resolution seismic profiling began in 1984 and continued in 1985 and 1987, providing detailed morphology of the Fram Strait sea floor and permitting better definition of its morphotectonics. The 1984 survey presented in this paper provided a complete set of bathymetric data from the southernmost section of the Svalbard Transform, including the Molloy Fracture Zone, connecting the Knipovich Ridge to the Molloy Ridge; and the Molloy Deep, a nodal basin formed at the intersection of the Molloy Transform Fault and the Molloy Ridge. This nodal basin has a revised maximum depth of 5607 m water depth at 79°8.5N and 2°47E. 相似文献
26.
Modest observations and numerical experiments were conducted to investigate circulation and brackish water dispersal in a
coastal lagoon southwest of Taiwan. The Chi-Ku Lagoon, partially shielded from the sea by a string of sandbar barriers with
two entrances among them, receives modest and episodic runoff from Chi-Ku Stream. Flood and ebb tidal streams entering and
leaving the two entrances are found to converge and diverge in a flow stagnation area inside the lagoon. Under weak wind conditions,
brackish water is preferentially retained in the flow stagnation area. Besides the observations, scenario runs using a three-dimensional
numerical model also indicate strong modulation by monsoon winds. Both summer southwest monsoon and winter northeast monsoon
reduce brackish water retention; the latter is found to be more effective.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
27.
28.
As a fundamental study to evaluate the contribution of the Kuroshio to primary production in the East China Sea (ECS), we
investigated the seasonal pattern of the intrusion from the Kuroshio onto the continental shelf of the ECS and the behavior
of the intruded Kuroshio water, using the RIAM Ocean Model (RIAMOM). The total intruded volume transport across the 200m isobath
line was evaluated as 2.74 Sv in winter and 2.47 Sv in summer, while the intruded transport below 80m was estimated to be
1.32 Sv in winter and 1.64 Sv in summer. Passive tracer experiments revealed that the main intrusion from the Kuroshio to
the shelf area of the ECS, shallower than 80m, takes place through the lower layer northeast of Taiwan in summer, with a volume
transport of 0.19 Sv. Comparative studies show several components affecting the intrusion of the Kuroshio across the 200 m
isobath line. The Kuroshio water intruded less onto the shelf compared with a case without consideration of tide-induced bottom
friction, especially northeast of Taiwan. The variations of the transport from the Taiwan Strait and the east of Taiwan have
considerable effects on the intrusion of the Kuroshio onto the shelf. 相似文献
29.
南极布兰斯菲尔德海峡表层沉积物的酸解烃 总被引:1,自引:0,他引:1
本文研究了南极布兰斯菲尔德海峡表层沉积物的酸解烃分布特征,并佐以热释汞和蚀变碳酸盐的分析。从酸解烃中甲烷含量的低值和C1/(C2+C3)比值,以及乙烯的存在等判断,布兰斯菲尔德海峡沉积物的烃类气体来自于生物成因。 相似文献
30.
中国台湾地区地处欧亚板块与菲律宾海板块之间,地震活动频繁.本文报道了 我国台湾地区及其邻近海域1985~2002年间5.5级以上地震的条带内外频度比分 布,并着重研究了1999—2002年中发生的3次7.5级以上地震前的条带现象.其结 果表明:台湾地区近期发生的3次7.5级以上大地震前,5.5级以上地震呈条带分 布.这些条带符合条带内地震个数Nin≥6的条件,符合条带内、外频度比Nin/(Nin Nout)≥75%的条件,也符合条带长宽比大于5的要求,只是与板内地震条带相比,条 带的长度较短. 相似文献