Dynamics of fatty acids in newly biosynthesized phytoplankton cells and seston during a spring bloom off the west coast of Hokkaido Island, Japan

¹³C uptake experiments were carried out at a station off the west coast of Hokkaido Island, Japan, during the period between late winter and spring bloom in 1997. The composition of newly biosynthesized particulate fatty acids was determined using a ¹³C tracer and gas chromatography/mass spectrometry (¹³C GC/MS), and compared with that of particulate matter (seston). Two fatty acid compositional ratios revealed that diatoms biomass (16:1(n−7)/16:0, ∑C₁₆/∑C₁₈) were strikingly high in new cells compared with seston on 17 April, coinciding with the dominance of fucoxanthin. In this study, the Polyunsaturation Index (a measure of the percentage of C₁₆ fatty acids that are polyunsaturated) in new cells is generally close to that in seston, while there was a notable discrepancy between new cells and seston in surface (10 m) waters on 17 April. This large difference between new cells and seston is ascribed to: (1) an increase of newly synthesized storage lipids (mainly 16:0 and 16:1) induced by nitrogen limitation in the top 10 m of the water column; (2) an addition of earlier synthesized phytoplankton cells (high Polyunsaturation Index at logarithmic growth stage) and non-phytoplankton components (detritus and bacteria and zooplankton) into seston. The highest Polyunsaturation Index of C₁₆ fatty acids in seston (33%) occurred at 100 m water depth. This may be caused by “settling planktonic aggregates” or “diatom resting spores”. In the present study, it is reasonable to suggest that the Polyunsaturation Index of C₁₆ fatty acids can be a useful indicator for the ecophysiological state of marine diatom populations.     

海南岛西岸上升流对波浪混合的敏感性研究

The coupled ocean–atmosphere–wave–sediment transport(COAWST) modeling system is employed to investigate the role of wave-mixing playing in the upwelling off the west coast of Hainan Island(WHU). Waves,tides and sea surface temperature(SST) are reproduced reasonably well by the model when validated by observations. Model results suggest the WHU is tidally driven. Further investigations indicate that inclusion of wave-mixing promotes the intensity of the WHU, making the simulated SST become more consistent with remote-sensed ones. Dynamically, wave-mixing facilitates the "outcrop" of more upwelled cold water, triggering stronger WHU and leading to a three-dimensional dynamical adjustment. From the perspective of time, wavemixing contributes to establishing an earlier tidal mixing front strong enough to generate WHU and that is, WHU may occur earlier when taking wave-mixing into consideration.     

Hydrological conditions and circulation off the west coast of the North Island,New Zealand

Temperature and salinity surveys were carried out in the Tasman Sea in winter (August 1973) and summer (February‐March 1974). In both surveys the presence of the Westland Current was indicated by the distribution of surface water properties; in summer it was associated with a subsurface salinity maximum. The current extended further northwards in summer than in winter. In summer, an east‐going geostrophic flow at about latitude 35°S separated on approaching New Zealand; part of the flow passed north around the North Island and part moved slowly eastwards in the deeper off‐shore water to at least latitude 38°S. The West Auckland Current was apparent in the winter, but not in the summer. To the west of Cape Reinga, relatively low values of surface temperature and salinity are probably associated with upwelling between Cape Reinga and the Three Kings Islands. Upwelling was observed along the coast between Kaipara and Manukau Harbour.     

2015年夏季海南岛东部沿岸物理结构及浮游植物群落

琼东上升流（EHU）是南海北部最强劲的上升流系统之一。它的水动力过程已经被很多研究所揭示,但是它的浮游植物群落依然不清楚。通过利用卫星遥感数据和2015年上升流季节的航次数据,我们首次阐明了琼东上升流区域（EHU）和其临近区域雷州半岛东部上升流区（ELPU）浮游植物生物量和群落的空间结构。在夏季季风的驱动下,我们在琼东沿岸发现了一个显著的低温高盐冷舌。由于雷州半岛东部大陆架宽广平缓,ELPU比EHU相对较弱。在EHU,由于受潮汐和风浪混合的影响,高溶解氧浓度 (>6.0 mg/l)几乎从表层延伸到30米深度。其次,低溶解氧的海水(<6.0 mg/l, 缺氧)被上升流从底层抽吸到上层。ELPU和EHU相比有更差的DO状况,在EHU,底层DO浓度由于大量的消耗,浓度甚至低于3.5 mg/l。在EHU,浮游植物生物量最大值出现在30米水层而不是在表层,约为1.5 mg/m³。这表明了上升流对于浮游植物生长和DO分布的影响范围。由于营养物质输入丰富, ELPU处的浮游植物生物量比EHU高很多。在EHU处,浮游植物生物量最大值可以达到4.0 mg/m³。浮游植物生物量在EHU和ELPU的沿岸区域则降低到了大约0.2~0.3 mg/m³,而这个值与远海接近。在EHU的近岸,浮游植物群落结构被硅藻所主宰,大约占了浮游植物生物量的50%。原核生物（大约40%）、绿藻（大约20%）、原绿球藻（大约20%）组成了EHU的近岸的主要群落。在ELPU,硅藻大约占了浮游植物生物量的80%,其次是绿藻,这表明与EHU相比,这个区域是一个相对不同的生态系统。     

Demersal communities off the west coast of South Africa

To describe demersal communities off the west coast of South Africa, collections of all species of fish, cephalopods and crustaceans made during four cruises in the area during January and July have been analysed. Hierarchical classification methods were employed to determine species and sample associations. The results showed that the species could be split into two main groups, the first containing Merluccius paradoxus (the dominant species both in abundance and frequency of occurrence) and other species normally found in deep (> 380 m) water. The second group is represented by species that live on the continental shelf, M. capensis being the most abundant. The boundary separating the deep-sea community from that of the shelf follows approximately the 385-m isobath. Seasonal variations in the number of main associations as well as in their spatial location are documented.     

Nutrient variability during El Niño 1997–98 in the California current system off central California

Nutrient conditions off central California during the 1997–98 El Niño are described. Data were collected on 11 cruises from March 1997 to January 1999 along a hydrographic section off central California, as well as every two weeks at a coastal station in Monterey Bay. Perturbations associated with El Niño are shown as anomalies of thermohaline and nutrient distributions along this section. The anomalies were obtained by subtracting seasonal averages for the period from April 1988 to April 1991 from the 1997–98 observations. The first indications of El Niño conditions (high sea levels) were observed at Monterey between late May and early June 1997, but the coastal nutricline did not begin to deepen until August 1997. It reached maximum depth of 130 dbar in January 1998 at the time that maximum sea level anomalies were observed. During this period: (1) the highest subsurface temperature anomalies coincided with subsurface nutrient anomaly minima at the depth of the pycnocline; (2) southern saline and nutrient-poor waters occupied the upper 80 dbar of the water column along the entire section; and (3) nitrate levels were close to zero in the euphotic zone, collapsing the potential new primary production in the coastal domain. At the end of February 1998, the nutricline shoaled to 40 dbar at the coast although it remained anomalously deep offshore. Higher temperatures and lower nutrient levels were observed for the entire section through August 1998 although in contrast with the previous winter, there was a strong freshening mainly due to an onshore movement of subarctic waters.     

ENSO发展期琼东上升流的动力过程响应差异

上升流是海洋中最重要的海洋现象之一,通过ROMS数值模型模拟并研究了2000—2013年间琼东上升流对ENSO信号(2002和2009年作为典型El Nio年; 2008和2010年作为典型La Nia年)的响应。结果表明,琼东上升流对ENSO气候事件有明显的响应。在El Nio信号较强时琼东上升流减弱,近岸海域水温升高;而在La Nia信号较强时琼东上升流加强,沿岸海域水温降低。对海面风场以及琼东海域沿岸流的分析表明,ENSO信号通过局地海面风场以及沿岸流对琼东上升流产生影响,并且风和沿岸流对琼东上升流的影响是协同的,在El Nio期间均不利于上升流的发展,而在La Nia期间二者的变化均有助于上升流的强化。     

Cetaceans sighted off the west coast of the south Island,New Zealand,Summer 1970 (note)

Records are presented of sightings of 6 cetacean species (15 common dolphins, Delphinus delphis Linnaeus, over 5000 dusky dolphins, Lagenorhynchus obscurus (Gray), approximately 74 bottlenose dolphins, Tursiops truncatus (Montagu), 8 sperm whales, Physeter catodon Linnaeus, 6 southern humpback whales, Megaptera novaeangliae lalandi (Fischer), and 36 southern pilot whales. Globi‐cephala melaena edwardii (Smith)) from m.v. Lloret Lopez II between 8 January and 2 April 1970. A large school of dusky dolphins was observed south of Solander Island. Monthly water temperatures in the summer of 1970 were high and in January ranged from 15.4°c (9.2 km west of Fiordland) and 21.6°c (55 km west of Cape Farewell), in February from 16.2°c (Fiordland) and 20.4°c (Cape Farewell), and in March from 16.0°c (Fiordland) and 20.5°c (Cape Farewell).     

Regimes and the history of the major fisheries off Canada's west coast

The major fisheries on the Pacific coast of Canada can be grouped into 12 species that have consistently represented about 80–90% of the total catch from the past to the present. A review of population dynamics of these species indicates that climate and the ocean environment have a major impact on their productivity. We review the history of Canada's Pacific coast fishery to show that trends in catch were similar to trends in the climate and ocean environment. Decadal scale patterns in climate and the ocean are termed regimes and we show that it is the regime scale of climate variability that most influences the long-term trends in the catches in these major fisheries. Ignoring the impacts of regime shifts on the abundance trends in the future could result in collapses of major fisheries. The difficulty of knowing when a regime shift will occur may be overcome as we discover more about the mechanisms that affect the decadal-scale trends in the rotational velocity of the solid earth which is measured as the length of day (LOD).     

Macrobenthic polychaete assemblages of the continental shelf and upper slope off the west coast of the South Island,New Zealand

Polychaete assemblages are described from replicate box‐core samples collected in summer 1983 at 18 stations on the continental shelf and upper slope (28–943 m) off the west coast of the South Island, New Zealand, south‐eastern Tasman Sea (c. 41–43°S, 169–172°E). Three main station groupings were identified by multivariate analysis: (1) inner shelf sandy stations characterised by Prionospio australiensis, Aricidea (Acesta) sp., Magelona cf. dakini, Paraprionospio aff. pinnata, Aglaophamus sp., Heteromastus filiformis, and Magelona sp.; (2) middle to outer shelf muddy stations characterised by Levinsenia cf. gracilis, Prionospio australiensis, Paraprionospio coora, Aglaophamus verrilli, and Auchenoplax mesos; and (3) upper slope sandy mud or mud stations characterised by Prionospio ehlersi. A combination of water depth and sediment clay content provided the best correlation with the biotic pattern. Spionidae was the most abundant family (49% of polychaete individuals), which may reflect the scope for opportunistic species in a shelf environment characterised by a high input of terrigenous sediment and episodic upwelling.     

琼东沿岸泥质沉积常量元素地球化学特征

对南海北部陆架琼东沿岸泥质区$20孔进行了岩性、粒度和常量元素分析,初步探讨了该泥质区常量元素地球化学特征.S20孔岩性较均一,主要为黏土质粉砂,研究区受相对单一而稳定的水动力条件控制.常量元素含量变化符合“元素的粒度控制律”,R型因子分析结果表明,第一因子P2O5,MnO,TiO2,A12O3,Fe2O3和K2O等的...     

Marine nekton off Oregon and the 1997–98 El Nino

Several species of migratory, warm-water, oceanic fishes invaded Oregon waters during the summer of 1997. Also, the jumbo squid (Dosidicus gigas), common in the eastern tropical Pacific, was reported for the first time in 1997 and was caught in large numbers. The occurrence of these oceanic nekton was associated with inshore advection of anomalously warm water. During 1998, after arrival of the main El Niño signal, some warm-water coastal fishes appeared off Oregon. However, unlike observations off California, fewer species of warm-water coastal fishes were noted during the 1997–98 El Niño than during the 1982–83 El Niño.     

Surficial sediments on the continental margin off the west coast of South Africa

A combination of climatic and oceanic factors has resulted in slow sedimentation rates on the continental shelf off the west coast of South Africa since Tertiary times. This has enabled a study to be made of the residual Late Tertiary, relict Pleistocene and Holocene sediments.Sediments on the continental shelf form rough belts parallel to the coast. Most of the coarse sediment is confined to the littoral zone and Holocene mud is concentrated at the base of a rocky nearshore platform. A veneer of Quaternary quartzitic sand seawards of the Recent mud belt wedges out onto a Tertiary erosion surface on the mid shelf. Residual glauconite and phosphorite sands derived by erosion during Tertiary sea-level fluctuations cover large parts of the mid shelf in the south. Most of the slope and parts of the outer shelf in the north are draped by Recent foraminiferal and coccolithophorid debris.     

热带太平洋海面对EL97／98事件的响应及ENSO预测

本文分析了1996－1998年逐月太平洋海面距平资料及热带太平洋海面赤道槽、脊及上层海水体积变化资料，清楚地看到20世纪最强的一次EL97／98事件，不仅基本特征明显，而且太平洋海面变化与其有密切的响应关系，受此启发，作者依据1975－2000年间赤道槽、脊、逆流槽及热带太平洋上层海水体积变化的历史资料，经年周期滑动平均数据处理和采用基于均生函数的正交化筛选建模方法，建立了各单预测因子周期外延的ENSO预测模式。结果表明，本预测模式除把单预测因子序列的历史变化趋势反映和预测出来，还揭示了历史上的El Nino事件发生了经滑动平均后的赤道脊或热带太平洋上层海水体积的峰值附近，结束于谷底附近，La Nina则出现在滑动平均后的赤道脊谷底上升至均值期间的一般规律性。根据各单预测因子周期外延曲线的峰、谷变化，预测下一次El Nino事件将于2001年下半年至2002年上半年期间形成。     

Sea level response to ENSO along the central California coast: how the 1997–1998 event compares with the historic record

Long-term monthly sea level and sea surface temperature (SST) anomalies from central California show that during winter months, positive anomalies are associated with El Niño events and the negative ones with La Niña events. There is no significant impact on monthly mean anomalies associated with Pacific decadal oscillations, although there is a tendency for more extreme events and greater variance during positive decadal oscillations. The very strong 1997–1998 El Niño was analyzed with respect to the long-term historic record to assess the forcing mechanisms for sea level and SST. Beginning in the spring of 1997, we observed several long-period (>30 days) fluctuations in daily sea level with amplitudes of over 10 cm at San Francisco, California. Fluctuations of poleward long-period alongshore wind stress anomalies (AWSA) are coherent with the sea level anomalies. However, the wind stress cannot entirely account for the observed sea level signals. The sea level fluctuations are also correlated with sea level fluctuations observed further south at Los Angeles and Tumaco, Columbia, which showed a poleward phase propagation of the sea level signal. We suggest that the sea level fluctuations were, to a greater degree, forced by the passage of remotely generated and coastally trapped waves that were generated along the equator and propagated to the north along the west coast of North America. However, both local and remote AWSA can significantly modulate the sea level signals. The arrival of coastally trapped waves began in the spring of 1997, which is earlier than previous strong El Niño events such as the 1982–1983 event.     

The nature and maximum extent of glacial sediments off the west coast of Wales

Offshore drilling and coring together with high-resolution seismic surveys have established that the southern Irish Sea was extensively glaciated during the Devensian stage. Ice flowed southwards from Scotland and overran the western tip of the Lleyn peninsula, before competing with local Welsh ice in Cardigan Bay. It eventually terminated its advance at the southern entrance to St. Georges Channel. To date no glacial sediments have been found on the sea floor to the south of this limit.During deglaciation, the shallower regions of the Irish Sea area underwent a short but intensive period of erosion which produced numerous meltwater channels. These subsequently acted as traps for the deposition of estuarine sediments associated with the early stages of the Flandrian Sea Transgression. The reworking of glacial drifts by marine action occurred primarily during the passage of the Flandrian surf zone and in most areas has now ceased.     

The inorganic carbon system in the coastal upwelling region west of Vancouver Island,Canada

We present inorganic carbon data from the coastal upwelling region west of Vancouver Island, Canada $\text{(∼48.5°}\text{N}\text{,}\text{126°}\text{W}\text{)}$ directly after an upwelling event and during summer downwelling in July 1998. The inner-shelf buoyancy current, the outer-shelf and the slope regions are contrasted for both wind regimes (up- and downwelling). Results show strong biological drawdown of the partial pressure of carbon dioxide (pCO₂) in response to upwelling over the outer-shelf. In contrast, measured pCO₂ is exceptionally high $\text{(p}\text{CO}{}_2\text{>1000}\text{ppm}\text{)}$ in the inner-shelf current, where biological uptake of carbon is consistently large. The biological C:N uptake ratio appears to increase when nitrogen becomes limiting (during downwelling), while the POC:PON ratio is relatively constant (slightly lower than the Redfield ratio) suggesting that excess carbon uptake does not go into the POC pool. As expected, large cells dominate where measured primary productivity is greatest. Sub-surface inorganic carbon (and pCO₂) is high over the shelf. We suggest that carbon concentrations may be higher in coastal waters because of remineralization associated with high productivity that is confined to a smaller volume of water by bathymetry. At the coast these sub-surface concentrations are more efficiently mixed into the surface (especially during winter) relative to deeper offshore regions. Thus, despite high primary production, coastal waters may not aid in sequestration of atmospheric carbon.     

A preliminary rotary spectral analysis of inertial currents off the west coast of Nevj/ Zealand (Note)

Results from a preliminary spectral analysis of inertial currents at a site with co‐ordinates 42° 1.73’ S, 168°41.1 l'E and a depth of 1505 m are described. Rotary spectral analysis indicates that inertial currents form a significant constituent of the observed oscillatory currents recorded.     

Iron fertilization of Trichodesmium off the west coast of Barbados: A one-dimensional numerical model

A one-dimensional quasi-Eulerian model, describing the biological and chemical interactions of autotrophic and heterotrophic plankton populations within the upper 100 m of the water column, was used to explain the relative impact of iron fertilization from Saharan dust on phosphorus cycling by the cyanobacterium, Trichodesmium spp. We examined the Caribbean surface waters off the west coast of Barbados using seasonal cases of dust delivery (summer peak) in relation to periods of elevated phosphorus stocks found in episodic pulses of Amazon River water advected past Barbados by the Guiana Current. The additional iron and phosphorus supplied by fluvial sources, available after biological depletion of nitrogen, could alleviate the growth limitation of Trichodesmium far downstream of the river plumes. The model results were compared with measurements made of Trichodesmium stocks 8 km off the west coast of Barbados. Modeled concentrations within the low-salinity Amazon plumes reached ∼7.4 mg chl m⁻², as seen at Barbados. In the absence of the low-salinity signal, the Trichodesmium biomass shifted to phosphorus limitation with little response to iron fertilization. This indicates that Trichodesmium stocks may indeed be mainly a function of phosphorus availability within the upper water column. Therefore, the supply of phosphorus from subtropical/tropical rivers, such as the Amazon and Orinoco, limits the potential cyanophyte response, despite adequate atmospheric iron delivery. This alters our view not only of the western North Atlantic nitrogen budget, but potentially several regions downstream of low N:P river systems.