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We examine the effect of a northward shift in the position of the southern hemisphere subpolar westerly winds (SWWs) on the vertical and horizontal distribution of temperature and salinity in the world ocean. A northward shift of the SWWs causes a latitudinal contraction of the subpolar gyres in the southern hemisphere (SH). In the Indian and Pacific, this leads to subsurface warming in the subtropical thermocline. As the southern margins of the gyres move into latitudes characterised by warmer surface air temperature (SAT), the layers at mid-depth below 400 m depth become ventilated by warmer water. We characterize the approximation of the ventilated thermocline in our coarse resolution model using a set of passive tracer experiments, and illustrate how the northward shift in the SWWs causes an equatorward shift in the latitude of origin of water ventilating layers deeper than 400 m in the Indian and Pacific, leaving the total surface ventilation of the upper 1200 m unchanged. In contrast, the latitudinal constraint on the Antarctic Circumpolar Current posed by the Drake Passage causes a cooling and freshening throughout the Atlantic thermocline; here, subsurface thermocline water originates from higher latitudes under the wind shift. On longer timescales Atlantic cooling and freshening is reinforced by a reduction in North Atlantic Deep Water (NADW) formation and surface salinification of the Indian and Pacific Oceans. In effect, the latitude of zero wind stress curl in the SWWs regulates the relative importance of the “cold water route” via the Drake Passage and the “warm water route” associated with thermocline water exchange via the Indian Ocean. Thus, a more northward location of the SWWs corresponds with a reduced salinity contrast between the Indian/ Pacific Oceans and the Atlantic. This results in reduced NADW formation. Also, a more northward location of the SWWs facilitates the injection of cool fresh Antarctic Intermediate Water into the South Atlantic subtropical gyre. Beyond these changes, on a millennial timescale, the deep ocean warms throughout the water column in response to the wind shift. Global salinity stratification also becomes less stable, as more saline water remains at the surface and accumulates in the Indian and Pacific thermocline. The freshening of the deep ocean reflects a reduced stirring of the global ocean due to reduced net circulation arising from a misalignment between the westerlies and the topographically constrained ACC. Our results lend support to the idea that a more equatorward location of the SWW maximum during glacial climates contributed to cooler and fresher conditions in the Atlantic, inhibiting NADW. 相似文献
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南黄海浮游动物主要种类数量分布年间比较 总被引：3，自引：0，他引：3
分析对比1959年、1982年、1998-2000年以及2007-2010年4个不同时期南黄海中部（34.25°~37.45°N,122.00°~124.00°E）浮游动物主要优势种中华哲水蚤（Calanus sinicus）、太平洋磷虾（Euphausia pacifica）和强壮箭虫（Sagitta crassa）数量时空变化及其与温度、盐度和太平洋年代际震荡指数（Pacific Decadal Oscillation,PDO）变动的关系。结果显示,温度可能对中华哲水蚤和太平洋磷虾数量分布影响较大;强壮箭虫则受盐度影响较大。PDO暖位相时期中华哲水蚤和太平洋磷虾数量显著低于冷位相时期,强壮箭虫则相反。中华哲水蚤和太平洋磷虾丰度与提前3个月PDO值呈显著正相关,强壮箭虫丰度仅与当月PDO值呈显著正相关。 相似文献
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西太平洋暖池变异及其对西太平洋次表层海温场的影响 总被引：9，自引：0，他引：9
应用热带太平洋上层XBT温度资料,分析研究了西太平洋暖池区(0°～16°N,125°～145°E)上层海洋的变化特征以及与西太平洋次表层海温场之间的关系.研究表明,西太平洋暖池区的垂向温度存在显著的年际变化,尤其在次表层(120～200m)的变化最为明显.西太平洋暖池区的次表层冷暖信号明显早于西太平洋次表层的海温异常.分析发现,西太平洋暖池区的海温异常是导致整个西太平洋次表层海温场变异的关键区,当西太平洋暖池区的次表层冷暖信号加强时,3～4个月后西太平洋海温场出现大范围的冷暖异常. 相似文献
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The zooplankton community of the subarctic Pacific is relatively simple, and contains a similar set of major species in all deep water areas of the subarctic Pacific. Their role in the food web varies considerably between coastal and offshore locations. In the oceanic gyres, microzooplankton and other mesozooplankton taxa replace phytoplankton as the primary food source for the dominant mesozooplankton species. Micronekton and larger zooplankton probably replace pelagic fish as major direct predators. Productivity and upper ocean biomass concentrations are intensely seasonal, in part because of seasonality of the physical environment and food supply, but also because of life history patterns involving seasonal vertical migrations (400–2000 m range) and winter dormancy. During the spring–summer season of upper ocean growth, small scale horizontal and vertical patchiness is intense. This can create local zones of high prey availability for predators such as planktivorous fish, birds, and marine mammals. On average, the cores of the subarctic gyres have lower biomass and productivity than the margins of the gyres. There is also some evidence that the Western Gyre is more productive than the Alaska Gyre, but more research is needed to confirm whether this east–west gradient is permanent. There is increasing evidence that the pattern of zooplankton productivity is changing over time, probably in response to interdecadal ocean climate variability. These changes include 2–3 fold shifts in total biomass, 30–60 day shifts in seasonal timing, and 10–25% changes in average body length. 相似文献
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INTRODUCTIONSincetheTOGA-COARElOP(October1992--March1993),usingthelOPdatamanyscientistshaveanalyzedthedifferenttimescaleair-seainteractionduringoccurringanddevelopingperiodof1992/1993EINifio,andespeciallyemphasizedtheintraseasonalvariation(Wuetal.,1993;Liu,1993;WuandSheng,1993).ThishasgottenanewunderstandingoftheEINino*ThisworkissupportedbytheNationalKeyProjectStudiesonShort-rangeClimatePredictionSysteminChinaundercontractNo.96--908-04-02--2.1.FirstinstituteofOceanography,S… 相似文献
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A.F. Hofmann E.T. PeltzerP.M. Walz P.G. Brewer 《Deep Sea Research Part I: Oceanographic Research Papers》2011,58(12):1212-1226
The marked increase in occurrences of low oxygen events on continental shelves coupled with observed expansion of low oxygen regions of the ocean has drawn significant scientific and public attention. With this has come the need for the establishment of better definitions for widely used terms such as “hypoxia” and “dead zones”. Ocean chemists and physicists use concentration units such as ??molO2/kg for reporting since these units are independent of temperature, salinity and pressure and are required for mass balances and for numerical models of ocean transport. Much of the reporting of dead zone occurrences is in volumetric concentration units of mlO2/l or mgO2/l for historical reasons. And direct measurements of the physiological state of marine animals require reporting of the partial pressure of oxygen (pO2) in matm or kPa since this provides the thermodynamic driving force for molecular transfer through tissue. This necessarily incorporates temperature and salinity terms and thus accommodates changes driven by climate warming and the influence of the very large temperature range around the world where oxygen limiting values are reported. Here we examine the various definitions used and boundaries set and place them within a common framework. We examine the large scale ocean pO2 fields required for pairing with pCO2 data for examination of the combined impacts of ocean acidification and global warming. The term “dead zones”, which recently has received considerable attention in both the scientific literature and the press, usually describes shallow, coastal regions of low oxygen caused either by coastal eutrophication and organic matter decomposition or by upwelling of low oxygen waters. While we make clear that bathyal low oxygen waters should not be confused with shallow-water “dead zones”, as deep water species are well adapted, we show that those waters represent a global vast reservoir of low oxygen water which can readily be entrained in upwelling waters and contribute to coastal hypoxia around the world and may be characterized identically. We examine the potential for expansion of those water masses onto continental shelves worldwide, thereby crossing limits set for many not adapted species. 相似文献
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热带西太平洋暖池异常东伸与热带东太平洋增温 总被引：7，自引：1，他引：6
本文利用“Climate Diagnostics Bulletin”、“Oceanographic Monthly Summary”、美国夏威夷水位中心提供的资料以及TOGA-COAREIOP资料,分析了1992～1993厄尔尼诺事件中西太平洋暖池、东太平洋SST对异常风场的响应,结果指出:由于西风暴发而引起的西太平洋暖水向东输送,不仅导致西太平详水位降低,而且导致温跃层显着升高,进而引起上层海水热含量显着减少,这种减少在温跃层更为明显.东太平洋与此相反,热含量与温跃层深度出现正距平,正距平中心出现时间比西太平洋的负距平均晚两个月;暖池28℃等温线的异常东伸是海流对低空西风异常直接响应的结果,定量估算表明,纬向流异常所引起的温度平流是暖池28℃等温线异常东伸的主要动力,是热带东太平洋异常增温的主要原因之一. 相似文献
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Fifty years of measurements at Ocean Station Papa (OSP, 50°N, 145°W) show trends in the interior waters of the subarctic Pacific that are both impacted by short term (few years to bi-decadal) atmospheric or ocean circulation oscillations and by persistent climate trends. Between 1956 and 2006, waters below the ocean mixed layer to a depth of at least 1000 m have been warming and losing oxygen. On density surfaces found in the depth range 100-400 m (σθ = 26.3-27.0), the ocean is warming at 0.005-0.012 °C y−1, whereas oxygen is declining at 0.39-0.70 μmol kg−1 y−1 or at an integrated rate of 123 mmol m−2 y−1 (decrease of 22% over 50 years). During this time, the hypoxic boundary (defined as 60 μmol O2 kg−1) has shoaled from ∼400 to 300 m. In the Alaska Gyre, the 26.2 isopycnal occasionally ventilates, whereas at OSP 26.0σθ has not been seen at the ocean surface since 1971 as the upper ocean continues to stratify. To interpret the 50 year record at OSP, the isopycnal transport of oxygenated waters within the interior of the subarctic Pacific is assessed by using a slightly modified “NO” parameter [Broecker, W., 1974. “NO” a conservative water-mass tracer. Earth and Planetary Science Letters 23, 100-107]. The highest nitrate-oxygen signature in interior waters of the North Pacific is found in the Bering Sea Gyre, Western Subarctic Gyre and East Kamchatka Current region as a consequence of winter mixing to the ∼26.6 isopycnal. By mixing with low NO waters found in the subtropics and Okhotsk Sea, this signature is diluted as waters flow eastward across the Pacific. Evidence of low NO waters flowing north from California is seen along the coasts of British Columbia and SE Alaska. Oxygen in the subsurface waters of the Alaskan Gyre was supplied ∼60% by subarctic and 40% by subtropical waters during WOCE surveys, whereas such estimates are shown to periodically vary by 20% at OSP. Other features discernable in the OSP data include periods of increased ventilation of deeper isopycnals on an ∼18 year cycle and strong, short term (few month) variability caused by passing mesoscale eddies. The potential impacts of declining oxygen on coastal ecosystems are discussed. 相似文献
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海南岛近岸海域夏初浮游动物与环境因子的关系 总被引：4，自引：1，他引：3
根据2011年夏初在海南岛近岸海域采集的浮游动物样本,分析了该海域浮游动物的种类组成、优势种类、丰度、生态类群,生物多样性及均匀度,并对浮游动物与环境因子之间的关系进行了探讨。海南岛近岸海域共鉴定出终生性浮游动物164种,阶段性浮游幼体11个类群,其中以桡足类的种类最多,40属82种。优势种主要有棘皮动物幼体Echinodermata larva、鸟喙尖头溞Penilia avirostris、异体住囊虫Oikopleura dioica、长尾类幼体Macrura larva、肥胖软箭虫Ferosagitta enflata、羽长腹剑水蚤Oithona plumifera、小齿海樽Doliolum denticulatum、中型莹虾Lucifer intermedius、泡抱球虫Globigerina bulloides、微驼隆哲水蚤Acrocalanus gracilis等。海南岛近岸海域浮游动物丰度平均值为1 348.68ind/m3,东部海域浮游动物丰度最高,由近岸向远岸呈递减趋势,而北部湾海域和南部海域由近岸向远岸则呈先增后减的趋势。夏初由于受沿岸流和南海暖流的影响,海南岛近岸海域的生态类群以暖水沿岸种和广布暖水外海种为主。浮游动物多样性指数和均匀度平均值为3.03和0.72,东部海域的多样性指数和均匀度较低,主要原因是阶段性浮游幼体的偶然性暴发。相关性分析显示,海南岛近岸海域浮游动物丰度与pH值呈极显著负相关(p0.05,r=-0.360);与浮游植物丰度(PA)呈极显著正相关(p0.01,r=0.395);与盐度、DO、CODMn、NO3-N浓度、NH4-N浓度、PO4-P浓度成正相关,与温度、NO2-N浓度、SiO3-Si浓度呈负相关。 相似文献
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M. Byrne P. SelvakumaraswamyM.A. Ho E. WoolseyH.D. Nguyen 《Deep Sea Research Part II: Topical Studies in Oceanography》2011,58(5):712-719
The distribution of the sea urchin Heliocidaris erythrogramma coincides with the southeast Australia global change hot spot where marine ecosystems are warming significantly due to changes in ocean circulation. To address questions on future vulnerabilities, the thermotolerance of the planktonic life phase of H. erythrogramma was investigated in the climate and regionally relevant setting of projected near-future (2100) ocean warming. Experimental treatments ranged from 18 to 26 °C, with 26 °C representing +3-4 °C above recent ambient sea-surface temperatures. Developmental success across all stages (gastrula, 24 h; larva, 72 h; juvenile, 120 h) decreased with increasing temperature. Development was tolerant to a +1-2 °C increase above ambient, but significant deleterious effects were evident at +3-4 °C. However, larvae that developed through the early bottleneck of normal development at 26 °C metamorphosed successfully. The inverse relationship between temperature and planktonic larval duration (PLD) was seen in a 25% decrease in the PLD of H. erythrogramma at 24 and 26oC. Ocean warming may be advantageous to a subset of larvae through early settlement and reduction of the vulnerable planktonic period. This positive effect of temperature may help buffer the negative effects of ocean warming. In parallel studies with progeny derived from northern (Coffs Harbour) and southern (Sydney) H. erythrogramma, northern embryos had significantly higher thermotolerance. This provides the possibility that H. erythrogramma populations might keep up with a warming world through poleward migration of thermotolerant propagules, facilitated by the strong southward flow of the East Australian Current. It is uncertain whether H. erythrogramma populations at the northern range of this species, with no source of immigrants, will have the capacity to persist in a warm ocean. Due to its extensive latitudinal distribution, its potential developmental thermotolerance and independence of its lecithotrophic larvae from exogenous food and the need to make a functional skeleton, H. erythrogramma may be particularly robust to ocean change. 相似文献
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We assessed spatial and temporal variability in the physical environment of a subarctic estuary, and examined concurrent patterns of chlorophyll α abundance (fluorescence), and zooplankton and forage fish community structure. Surveys were conducted in lower Cook Inlet, Alaska, during late July and early August from 1997 through 1999. Principle components analysis (PCA) revealed that spatial heterogeneity in the physical oceanographic environment of lower Cook Inlet could be modeled as three marine-estuarine gradients characterized by temperature, salinity, bottom depth, and turbidity. The gradients persisted from 1997 through 1999, and PCA explained 68% to 92% of the variance in physical oceanography for each gradient-year combination. Correlations between chlorophyll α abundance and distribution and the PCA axes were weak. Chlorophyll was reduced by turbidity, and low levels occurred in areas with high levels of suspended sediments. Detrended correspondence analysis (DCA) was used to order the sample sites based on species composition and to order the zooplankton and forage fish taxa based on similarities among sample sites for each gradient-year. Correlations between the structure of the physical environment (PCA axis 1) and zooplankton community structure (DCA axis 1) were strong (r = 0.43-0.86) in all years for the three marine-estuarine gradients, suggesting that zooplankton community composition was structured by the physical environment. The physical environment (PCA) and forage fish community structure (DCA) were weakly correlated in all years along Gradient 2, defined by halocline intensity and surface temperature and salinity, even though these physical variables were more important for defining zooplankton habitats. However, the physical environment (PCA) and forage fish community structure (DCA) were strongly correlated along the primary marine-estuarine gradient (#1) in 1997 (r = 0.87) and 1998 (r = 0.82). The correlation was poor (r = 0.32) in 1999, when fish community structure changed markedly in lower Cook Inlet. Capelin (Mallotus villosus), walleye pollock (Theragra chalcogramma), and arrowtooth flounder (Atheresthes stomias) were caught farther north than in previous years. Waters were significantly colder and more saline in 1999, a La Niña year, than in other years of the study. Interannual fluctuations in environmental conditions in lower Cook Inlet did not have substantial effects on zooplankton community structure, although abundance of individual taxa varied significantly. The abundance and distribution of chlorophyll α, zooplankton and forage fish were affected much more by spatial variability in physical oceanography than by interannual variability. Our examination of physical-biological linkages in lower Cook Inlet supports the concept of “bottom-up control,” i.e., that variability in the physical environment structures higher trophic-level communities by influencing their distribution and abundance across space. 相似文献
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The results of multiyear observations of the seasonal and inter-annual variability of the population structure, abundance,
and biomass of the arctic calanoids copepod Calanus glacialis in the White Sea are presented. The spring season represents the most crucial period for the population’s seasonal dynamics.
During the spring, the maximal abundance, biomass, and contribution of C. glacialis to the total zooplankton biomass is observed. The interannual variability of the abundance is closely related to the timing
of the spring warming of the upper water column and the respective shifts of the onset of reproduction and the offspring development.
The development of a new generation to the overwintering copepodite stage IV is usually completed three to four weeks later
in the cold years compared to the warm ones. Our multiyear observations suggest that C. glacialis could be more tolerant of Arctic warming than it is usually believed. The high abundance of the C. glacialis population in the White Sea indicates that this arctic species is able to cope with the seasonal surface warming and should
continue to do so, being provided with the cold water “refuge” in the deep sea. 相似文献
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George L. Hunt Jr. Phyllis Stabeno Gary Walters Elizabeth Sinclair Richard D. Brodeur Jeffery M. Napp Nicholas A. Bond 《Deep Sea Research Part II: Topical Studies in Oceanography》2002,49(26)
We propose a new hypothesis, the Oscillating Control Hypothesis (OCH), which predicts that pelagic ecosystem function in the southeastern Bering Sea will alternate between primarily bottom-up control in cold regimes and primarily top-down control in warm regimes. The timing of spring primary production is determined predominately by the timing of ice retreat. Late ice retreat (late March or later) leads to an early, ice-associated bloom in cold water (e.g., 1995, 1997, 1999), whereas no ice, or early ice retreat before mid-March, leads to an open-water bloom in May or June in warm water (e.g., 1996, 1998, 2000). Zooplankton populations are not closely coupled to the spring bloom, but are sensitive to water temperature. In years when the spring bloom occurs in cold water, low temperatures limit the production of zooplankton, the survival of larval/juvenile fish, and their recruitment into the populations of species of large piscivorous fish, such as walleye pollock (Theragra chalcogramma), Pacific cod (Gadus macrocephalus) and arrowtooth flounder (Atheresthes stomias). When continued over decadal scales, this will lead to bottom-up limitation and a decreased biomass of piscivorous fish. Alternatively, in periods when the bloom occurs in warm water, zooplankton populations should grow rapidly, providing plentiful prey for larval and juvenile fish. Abundant zooplankton will support strong recruitment of fish and will lead to abundant predatory fish that control forage fish, including, in the case of pollock, their own juveniles. Piscivorous marine birds and pinnipeds may achieve higher production of young and survival in cold regimes, when there is less competition from large piscivorous fish for cold-water forage fish such as capelin (Mallotus villosus). Piscivorous seabirds and pinnipeds also may be expected to have high productivity in periods of transition from cold regimes to warm regimes, when young of large predatory species of fish are numerous enough to provide forage. The OCH predicts that the ability of large predatory fish populations to sustain fishing pressure will vary between warm and cold regimes.The OCH points to the importance of the timing of ice retreat and water temperatures during the spring bloom for the productivity of zooplankton, and the degree and direction of coupling between zooplankton and forage fish. Forage fish (e.g., juvenile pollock, capelin, Pacific herring [Clupea pallasii]) are key prey for adult pollock and other apex predators. In the southeastern Bering Sea, important changes in the biota since the mid-1970s include a marked increase in the biomass of large piscivorous fish and a concurrent decline in the biomass of forage fish, including age-1 walleye pollock, particularly over the southern portion of the shelf. Populations of northern fur seals (Callorhinus ursinus) and seabirds such as kittiwakes (Rissa spp.) at the Pribilof Islands have declined, most probably in response to a diminished prey base. The available evidence suggests that these changes are unlikely the result of a decrease in total annual new primary production, though the possibility of reduced post-bloom production during summer remains. An ecosystem approach to management of the Bering Sea and its fisheries is of great importance if all of the ecosystem components valued by society are to thrive. Cognizance of how climate regimes may alter relationships within this ecosystem will facilitate reaching that goal. 相似文献
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Nikolay P. Nezlin Paul M. DiGiacomo Dario W. Diehl Burton H. Jones Scott C. Johnson Michael J. Mengel Kristen M. Reifel Jonathan A. Warrick Menghua Wang 《Estuarine, Coastal and Shelf Science》2008
Stormwater plumes in the southern California coastal ocean were detected by MODIS-Aqua satellite imagery and compared to ship-based data on surface salinity and fecal indicator bacterial (FIB) counts collected during the Bight'03 Regional Water Quality Program surveys in February–March of 2004 and 2005. MODIS imagery was processed using a combined near-infrared/shortwave-infrared (NIR-SWIR) atmospheric correction method, which substantially improved normalized water-leaving radiation (nLw) optical spectra in coastal waters with high turbidity. Plumes were detected using a minimum-distance supervised classification method based on nLw spectra averaged within the training areas, defined as circular zones of 1.5–5.0-km radii around field stations with a surface salinity of S < 32.0 (“plume”) and S > 33.0 (“ocean”). The plume optical signatures (i.e., the nLw differences between “plume” and “ocean”) were most evident during the first 2 days after the rainstorms. To assess the accuracy of plume detection, stations were classified into “plume” and “ocean” using two criteria: (1) “plume” included the stations with salinity below a certain threshold estimated from the maximum accuracy of plume detection; and (2) FIB counts in “plume” exceeded the California State Water Board standards. The salinity threshold between “plume” and “ocean” was estimated as 32.2. The total accuracy of plume detection in terms of surface salinity was not high (68% on average), seemingly because of imperfect correlation between plume salinity and ocean color. The accuracy of plume detection in terms of FIB exceedances was even lower (64% on average), resulting from low correlation between ocean color and bacterial contamination. Nevertheless, satellite imagery was shown to be a useful tool for the estimation of the extent of potentially polluted plumes, which was hardly achievable by direct sampling methods (in particular, because the grids of ship-based stations covered only small parts of the plumes detected via synoptic MODIS imagery). In most southern California coastal areas, the zones of bacterial contamination were much smaller than the areas of turbid plumes; an exception was the plume of the Tijuana River, where the zone of bacterial contamination was comparable with the zone of plume detected by ocean color. 相似文献
18.
Oceanographic influences on the distribution and relative abundance of market squid paralarvae (Doryteuthis opalescens) off the Southern and Central California coast 
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下载免费PDF全文 Market squid (Doryteuthis opalescens) are ecologically and economically important to the California Current Ecosystem, but populations undergo dramatic fluctuations that greatly affect food web dynamics and fishing communities. These population fluctuations are broadly attributed to 5–7‐years trends that can affect the oceanography across 1,000 km areas; however, monthly patterns over kilometer scales remain elusive. To investigate the population dynamics of market squid, we analysed the density and distribution of paralarvae in coastal waters from San Diego to Half Moon Bay, California, from 2011 to 2016. Warming local ocean conditions and a strong El Niño event drove a dramatic decline in relative paralarval abundance during the study period. Paralarval abundance was high during cool and productive La Niña conditions from 2011 to 2013, and extraordinarily low during warm and eutrophic El Niño conditions from 2015 to 2016 over the traditional spawning grounds in Southern and Central California. Market squid spawned earlier in the season and shifted northward during the transition from cool to warm ocean conditions. We used a general additive model to assess the variability in paralarval density and found that sea surface temperature (SST), zooplankton displacement volume, the log of surface chlorophyll‐a, and spatial and temporal predictor variables explained >40% of the deviance (adjusted r2 of .29). Greatest paralarval densities were associated with cool SST, moderate zooplankton concentrations and low chlorophyll‐a concentrations. In this paper we explore yearly and monthly trends in nearshore spawning for an economically important squid species and identify the major environmental influences that control their population variability. 相似文献
19.
福清湾及附近海域浮游动物的数量和分布 总被引：3，自引：0，他引：3
本文分析了2005年10月和2006年5月在福清湾及其附近海域采集的浮游动物样品,结果表明,福清湾已鉴定的浮游动物有64种,10类浮游幼体.分为4个生态类群,包括河口低盐类群,近岸暖温类群,近岸暖水类群和广布外海类群.浮游动物物种多样性指数春季高于秋季.春季浮游动物总个体数均值为(161ind/m3)高于秋季的(83ind/m3),春季生物量均值为(67.7mg/m3)低于秋季的(87.7mg/m3);浮游动物总个体数的平面分布,春季湾内西部水域最高,海坛海峡最少;秋季福清湾东部水域最高,湾内西部水域最少.浮游动物生物量和总个体数的平面分布趋势基本一致.另外还对浮游动物的分布与环境因子的关系进行了分析. 相似文献
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F. P. Chavez J. T. Pennington C. G. Castro J. P. Ryan R. P. Michisaki B. Schlining P. Walz K. R. Buck A. McFadyen C. A. Collins 《Progress in Oceanography》2002,54(1-4)
The physical, chemical and biological perturbations in central California waters associated with the strong 1997–1998 El Niño are described and explained on the basis of time series collected from ships, moorings, tide gauges and satellites. The evolution of El Niño off California closely followed the pattern observed in the tropical Pacific. In June 1997 an anomalous influx of warm southerly waters, with weak signatures on coastal sea level and thermocline depth, marked the onset of El Niño in central California. The timing was consistent with propagation from the tropics via the equatorial and coastal wave-guide. By late 1997, the classical stratified ocean condition with a deep thermocline, high sea level, and warm sea surface temperature (SST) commonly associated with El Niño dominated the coastal zone. During the first half of 1998 the core of the California Current, which is normally detected several hundred kilometers from shore as a river of low salinity, low nutrient water, was hugging the coast. High nutrient, productive waters that occur in a north–south band from the coast to approximately 200 km offshore during cool years disappeared during El Niño. The nitrate in surface waters was less than 20% of normal and new production was reduced by close to 70%. The La Niña recovery phase began in the fall of 1998 when SSTs dropped below normal, and ocean productivity rebounded to higher than normal levels. The reduction in coastal California primary productivity associated with El Niño was estimated to be 50 million metric tons of carbon (5×1013 g C). This reduction certainly had deleterious effects on zooplankton, fish, and marine mammals. The 1992–1993 El Niño was more moderate than the 1997–1998 event, but because its duration was longer, its overall chemical and biological impact may have been comparable. How strongly the ecosystem responds to El Niño appears related to the longer-term background climatic state of the Pacific Ocean. The 1982–1983 and 1992–1993 El Niños occurred during the warm phase of the Pacific Decadal Oscillation (PDO). The PDO may have changed sign during the 1997–1998 El Niño, resulting in weaker ecological effects than would otherwise have been predicted based on the strength of the temperature anomaly. 相似文献