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1.
Data collected during 7 years of seasonal surveys are used to investigate the distribution of phytoplankton biomass within the estuarine waters of the Strait of Georgia and Juan de Fuca Strait. Variability of the chlorophyll distribution is examined in relation to the density stratification, light availability and nutrient concentration. In the Strait of Georgia, both the horizontal and vertical distribution of chlorophyll are found to be linked to the presence of a near-surface layer of increased density stratification. Despite important year-to-year variability, the seasonal cycle of chlorophyll in the Strait of Georgia is dominated every year by relatively large near-surface concentrations in the spring that are linked to the seasonal increase in solar radiation onto the stratified near-surface layer. In the vertical, a sub-surface peak is observed around 10 m depth, corresponding to the depth of maximum water column stability. Nutrients within the euphotic zone are in general abundant, with the exception of the Strait of Georgia in summer where phytoplankton growth is potentially limited by low nitrate concentration near the surface. The depth of the euphotic zone is estimated along the thalweg of the estuary from transmissometer profiles. It appears to vary relatively little within the estuary from a minimum of 20 m in spring, near the mouth of the Fraser River, to an autumnal maximum of about 30 m in the northern Strait of Georgia. Finally, the estimated self-shading contribution to light attenuation is shown to be generally significant (5–10%) in the surface waters of the Strait of Georgia, during spring and summer, reaching values as high as 35% during the spring bloom. 相似文献
2.
渤海中部和渤海海峡及邻近海域浮游植物群落结构的初步研究 总被引：29，自引：5，他引：29
对渤海调查区浮游植物的群落及其动力学进行了初步研究。结果表明 ,浮游植物群落主要由硅、甲藻组成 ,也有少数的蓝藻、绿藻和硅鞭藻出现 ,其生态类型主要为温带近岸型。粒级大小以微型浮游植物为主 ,依次为小型浮游植物 (包括网采浮游植物 )、微微型浮游植物。浮游植物群落的平面分布与各环境因子密切相关 ,其中水体中化学和生物相互作用所形成的浮游植物团块是其平面分布的主要特征。调查海域存在三个典型的浮游植物区划 :渤海海峡区、渤海湾区和黄河河口区。追踪实验的结果表明 ,调查区浮游植物群落短周期 (几天 )的变化是由关键种所驱动而非优势种。渤海海峡浮游植物群落的周年变化为双周期型 ,春季水华主峰出现在 4月 ,而秋季次高峰出现在 9月。春季浮游植物以小型细胞硅藻占优群落为主 ,秋季以大型细胞硅藻 甲藻联合占优群落为主。群落季节和周年的变化以种类演替 (speciessuccession)为主而非种类接替 (speciessequence)。与历史调查资料相比 ,1 998— 1 999年的观测表明浮游植物群落由硅藻占绝对优势逐渐转变为硅藻 甲藻共存为主的群落。甲藻的占优以及绿藻在特定时期的普遍出现反映了渤海海区营养盐结构比例变化对海区生态系统结构的影响 ,氮 /磷比率的增加和硅 /氮比率的降低是造成这一结果的 相似文献
3.
Standing stock of phytoplankton and primary productivity in Penaeus orientalis larval multiplication releasing area of the Xiangshan Bay 总被引：1，自引：1，他引：0
INTRODUCTIONTheXiangshanBayisoneoftheimportantmarineaquaculturebasesinZhejiang.Since1982,themultiplicationreleasingexperimentsofPenaeusorzentalisKishinouyelarvalhavebeencarriedoutinthebay.Thestudyonthephytoplankton,chlaconcentrationandproductivityandthelifepatternofreleasedlarvaeprawnintheXiangshanBayisoneoftheimportanttasksoftheNationalKeyProject--AquaticExploitationTechniqueResearchinLakesandHarbors.TherearemanylargebaysandharborsalongChina'scoast,butonlyafewobservationshavebeend… 相似文献
4.
《Oceanologica Acta》1998,21(6):907-921
Phytoplankton distribution and primary productivity were investigated in the Bay of Seine (eastern English Channel, France) in spring and early summer of 1992 and 1994. In 1992, the horizontal distribution of phytoplankton species was determined over the whole Bay of Seine. In 1994, species distribution and primary productivity were studied along the salinity gradient of the Seine plume and in the neighbouring marine waters. Phytoplankton distribution was characterised by the permanent diatom dominance from early spring to early summer. The spring bloom did not occur uniformly over the bay, but was initiated in the marine waters, in the middle of the bay and progressed towards the coast where it developed, in June, in the diluted waters of the Seine plume. Phytoplankton distribution was also characterised by the dominance of large diatoms (Rhizosolenia) in marine waters and by the dominance of small species (Skeletonema costatum, Asterionella glacialis) in the plume waters. The greatest abundance of large diatoms was generally encountered below the euphotic zone. This accumulation seemed to be related to cell sedimentation and advection of marine waters below the diluted plume waters. The daily carbon productivity range was 1.4 to 3 g m−2 d−1. The highest values were measured in the plume waters (S > 28), suggesting the primary productivity in the plume was more controlled by light than by nutrients. The photic zone productivity/ chlorophyll a ratios (P/B; producted carbon per unit of Chla) were close to 40 mg mg−1 d−1 in the plume waters. P/B exceptionally reached 90 mg mg−1 d−1 in early summer. This value corresponded to a fast growing population of S. costatum. In marine waters, P/B varied from 22 mg mg−1 d−1, in spring, to 43 mg mg−1 d−1, in early summer. 相似文献
5.
Spring blooms of phytoplankton composed of centric diatoms developed in late February, March, and April in Otsuchi Bay on Sanriku ria coast, Japan. During this period, associated with prolonged seasonal west wind (>1 day), intense exchange of waters occurred between inside and outside the bay: outflow of nearsurface brackish water over inflow of oceanic water at depth. This circulation interrupted formation of the blooms, and transported phytoplankton populations seaward. By such water movements, a significant amount of nutrients in the bay was carried out, otherwise replenished into the bay, depending on water masses located outside the bay. Owing to irregular features of wind events, a bloom lasted from several days to a week. From February to April, supply of nutrients seemed to be replete except for the latter half of the bloom period, and estimates of the critical depth exceeded the depth of the bottom consistently. Thus, net growth of phytoplankton was expected throughout the observation period, and potentially blooms could be formed. However, the blooms were only formed under calm weather. We hypothesize that the exchange of waters dilutes populations in the bay, and that formation of the bloom, that is, accumulation of biomass depends on a balance between the growth of phytoplankton and the dilution of bay water. 相似文献
6.
Seasonal variations in dissolved organic carbon concentrations and characteristics in a shallow coastal bay 总被引：8，自引：0，他引：8
Dissolved organic matter (DOM) composition and dynamics in temperate shallow coastal bays are not well described although these bays may be important as local sources of organic carbon to ocean waters and are often sites of economically-important fisheries and aquaculture. In this study surface water samples were collected on a monthly to bi-monthly basis over two years from a mid-Atlantic coastal bay (Chincoteague Bay, Virginia and Maryland, USA). Dissolved organic carbon (DOC) concentrations and light absorbance characteristics were measured on sterile-filtered water, and high-molecular weight (> 1 kDa) dissolved OM (DOM) was isolated to determine stable isotope composition and molecular-level characteristics. Our time series encompassed both a drought year (2002) and a year of above-average rainfall (2003). During the dry year, one of our sites developed a very intense bloom of the brown tide organism Aureococcus anophagefferens while during the wet year there were brown tide bloom events at both of our sampling sites. During early spring of the wet year, there were higher concentrations of > 1 kDa DOC; this fraction represented a larger proportion of overall DOC and appeared considerably more allochthonous. Based upon colored dissolved organic matter (CDOM) and high-molecular weight DOM analyses, the development of extensive phytoplankton blooms during our sampling period significantly altered the quality of the DOM. Throughout both years Chincoteague Bay had high DOC concentrations relative to values reported for the coastal ocean. This observation, in conjunction with the observed effects of phytoplankton blooms on DOM composition, indicates that Chincoteague Bay may be a significant local source of “recently-fixed” organic carbon to shelf waters. Estimating inputs of DOC from Chincoteague Bay to the Mid-Atlantic Bight suggests that shallow productive bays should be considered in studies of organic carbon on continental shelves. 相似文献
7.
大亚湾生态监控区的浮游植物年际变化 总被引：2，自引：0，他引：2
依据国家海洋局、国家海洋局第三海洋研究所等权威机构2004~2007年所获的数据和资料,对大亚湾生态监控区近4a长时间尺度的浮游植物群落年际变化进行分析,通过物种组成、丰度变化、优势类群演替、群落结构及赤潮灾害事件来反映生境的退化,探讨其变化的主要原因及趋势。结果表明,浮游植物群落由暖水种占绝对优势转变为广温广布种占主导地位。种类与丰度呈逐年下降的态势,浮游植物丰度的分布保持西高东低,近岸高于远岸的特征,浮游植物的高丰度与营养盐丰富及温排水有关。终年以硅藻为优势种群,优势种演替具有明显的季节与年际变化,细长翼根管藻(Rhizosolenia alataf.gracillima)是春季稳定的优势种,柔弱拟菱形藻(Pseudo-nitzschia delicatissma)是夏季稳定的优势种,春末甲藻的优势度增加明显。浮游植物群落多样性指数呈逐年下降趋势,均匀度呈逐年上升态势。浮游植物的异常增殖及过度集中导致多样性较低,种间比例不均匀,群落结构单一。赤潮季节性发生频繁,发生频率及引发种类呈上升趋势,海洋环境脆弱。 相似文献
8.
分析了2009 年春季(5 月)渤海辽东湾网采浮游植物物种组成, 丰度分布, 生物多样性指数及群落相似性。春季共鉴定出浮游植物3 门23 属32 种, 主要隶属硅藻门和甲藻门, 生态类型多为温带近岸型和广布型种类, 少部分为暖海性物种或大洋性物种。优势种有夜光藻(Noctiluca scientillans)、翼鼻状藻(Proboscia alata)、旋链角毛藻(Chaetoceros curvisetus)、巨圆筛藻(Coscinodiscus gigas)和尖刺伪菱形藻(Pseudo-nitzschia pungens)等。浮游植物在各站位的细胞丰度分布不均匀, 其平面分布呈现由沿岸海域向海湾中部海域递减的趋势。Shannon-Wiener 指数、Pielou 指数较低, 群落结构简单, 稳定性较差。聚类分析结果表明群落之间的相似性较高。 相似文献
9.
In April 1996, a massive algal bloom of the coccolithophorid Gephyrocapsa oceanica developed in both Chita Bay and Atsumi Bay which comprise the bay known as Mikawa Bay of Japan. It was the first record of such a bloom in this area. In Chita Bay, the bloom persisted until the middle of May, however in Atsumi Bay, it remained until early June. From the analysis of salinity, water temperature, and current velocity and direction data, it is considered that the following mechanism accounts for the occurrence and maintenance of the bloom: Before the bloom, the standing crop of phytoplankton was poor, resulting in relatively rich nutrients throughout the bay. Thereafter, with the influx of oceanic water into Mikawa Bay, high salinity occurred firstly in Chita Bay. Under these hydrographic conditions, the bloom occurred first in Chita Bay, and extended throughout the bay with the clockwise circulation of water into Atsumi Bay. In Chita Bay, the bloom was influenced by rainfall and G. oceanica flowed out from this area. Whereas, in Atsumi Bay, the bloom persisted for longer due to the clockwise circulation and another influx of oceanic water. 相似文献
10.
大亚湾澳头海域硅藻、甲藻的数量变动及其与环境因子的关系 总被引：12，自引：1，他引：11
于1997年7月-1998年6月采集大亚湾澳头海域水样,根据《海洋监测规范》分析调查方法,研究了硅藻和甲藻的数量变动及其与环境因子之间的关系,共鉴定出浮游植物198种,其中硅藻98种,甲藻83种。结果表明,大亚湾浮游植物细胞密度较高,年平均细胞密度为424．7cells／ml,最高细胞密度为6689．8cells／ml,硅藻为浮游植物的主要类群。调查期间共发生藻类水华7次,硅藻可在全年各季节发生水华,而甲藻水华仅在春季发生。硅藻水华的消退与N的大量消耗有关,而甲藻水华对P消耗较大。结果表明,大亚湾合适的温度、盐度、气象条件、丰富的硅酸盐含量及N、P等营养盐的及时补充是大亚湾浮游植物数量高和水华频繁发生的主要原因,同时风、流等物理因素对藻类的聚积作用对水华的发生也有一定的促进作用。 相似文献
11.
This report presents a new analysis of the results of two hydrochemical surveys over the Ob Bay in 2010 performed by the Institute of Fisheries and Oceanography (VNIRO) and the Institute of Oceanology (IO RAS). The unique world feature of the Ob River-Ob Bay system is shown. The water volume in the bay exceeds the average annual runoff of the Ob River, being somewhat under the total runoff of all the inflowing rivers. Because of this, the complete renovation of the waters in the bay requires a long time. The within-year distribution of the runoff is characterized by both the flood waters and those of the Ob River winter runoff characterized by much different hydrochemical parameters registered even in the course of summer surveys in the bay. This fact, but not the biological transformation of the waters, as assumed previously, is the primary cause of the variability of the water composition in the bay. The summer waters of the Ob River reach the sea-ward boundary of the bay only in the next spring, enter the Kara Sea with the spring flood, and form lenses of desalinated waters in the sea. The autumn expeditions by the IO RAS found that the waters in the lenses were quite similar to the autumn waters in the bay, although these were the Ob River waters of different years, which was disregarded formerly. 相似文献
12.
2013年4月，2014年5月，2012年6月和2015年10月在印度尼西亚北部苏拉维斯蓝碧海峡（Lembeh Strait）进行了4个航次的海洋生态调查，研究了蓝碧海峡的浮游植物种类组成，以及浮游植物群落结构的季节变化及其驱动因子。四个航次的调查中记录了5类浮游植物和416个种（类）。调查区浮游植物密度平均为2348cells/L，硅藻和甲藻种类最多。蓝藻种类最少，但丰度很高。季风转换期的4月份和10月份浮游植物丰度总量较低，东南季风期间5月份和6月份的浮游植物丰度较高。除了束毛藻（Trichodesmium）之外，常见种是浮游硅藻。浮游植物的丰度和多样性的季节性变化明显。海链藻（Thalassionema）、拟菱形藻（Pseudo-nitzschia）和蓝藻类的束毛藻对群落的不相似性贡献最大。由于蓝碧海峡南部营养盐浓度较高，南部水域的硅藻和甲藻密度稍高于海峡北部。虽然，南北两个水体中蓝藻的分布趋于均匀，但蓝碧海峡南部也有较高密度。与雅加达湾以及中国的一些海湾相比，蓝碧海峡的浮游植物丰度相当低。分析表明，SE季风期间上升流营养盐是左右浮游植物丰度月变化的重要因素。蓝碧海峡浮游生态系原始，且接近天然本底，人类活动背景噪声低，能够清晰地响应大环境的变化，是研究浮游生态系统的理想区域。 相似文献
13.
Estimating direct and episodic atmospheric nitrogen deposition to a coastal waterbody 总被引：4，自引：0，他引：4
Direct deposition of atmospheric nitrogen to shallow coastal embayments is usually estimated, since insufficient field measurements are available. Using Waquoit Bay (Cape Cod, MA. USA) as a case study, and a recent review of literature, we determined reasonable bounds on wet and dry inputs of inorganic and organic N. Since precipitation and wind vary daily, we explored the potential of episodic events to stimulate phytoplankton blooms. Many coastal waterbodies like Waquoit Bay are small relative to their watersheds. Nevertheless, direct deposition of NH(3), NO(3)(-), and HNO(3) is significant in the loading budget. For Waquoit Bay, direct deposition was calculated to be 7-15.5 kg total N ha(-1)yr(-1), representing 70-150% of the atmospheric N reported to reach the bay via the watershed, and 20-45% of the total N reaching the bay from all land-based sources. Episodic events were estimated to deliver up to 65 mg N m(-2)day(-1), representing a phytoplankton stock of 12.3 mg Chl m(-2), an amount unlikely to stimulate dense blooms in shallow coastal waters in the northeastern United States. 相似文献
14.
To clarify the time change in water exchanges between Ise Bay and the adjacent ocean, repeated hydrographic observations were
conducted along the longitudinal section in Ise Bay. The results show that the mixing condition at the bay mouth (Irago Strait)
changed fortnightly in summer. During the spring tides, the strait water below the pycnocline was well-mixed and nearly homogeneous.
By contrast, it was weakly stratified during the neap tide. There is a strong negative correlation between the tidal range
and the density difference between the upper and lower layers at the strait. In summer, the intrusion depth of oceanic water
into the bay and consequent hydrographic conditions inside the bay changed frequently according to the tidal strength. During
the spring tides a prominent bottom front was created at the bay mouth, indicating that the strait water, which is a mixture
of oceanic and bay waters, intruded through the middle layer. On the other hand, during the neaps, cold and saline oceanic
water intruded through the bottom layer into the bay. The intrusion depth is significantly correlated with the tidal range.
It is considered that the wellmixed strait water, which has a density equivalent to the middle layer inside the bay, is lighter
than the bottom bay water and thus intrudes through the middle layer during the spring tides, while insufficient mixing makes
the bottom water at the strait heavier than the bay water, leading to the bottom intrusion during the neap tides. 相似文献
15.
《Estuarine, Coastal and Shelf Science》2005,62(1-2):25-40
The often-rapid deposition of phytoplankton to sediments at the end of the spring phytoplankton bloom is an important component of benthic–pelagic coupling in temperate and high latitude estuaries and other aquatic systems. However, quantifying the flux is difficult, particularly in spatially heterogeneous environments. Surficial sediment chlorophyll-a, which can be measured quickly at many locations, has been used effectively by previous studies as an indicator of phytoplankton deposition to estuarine sediments. In this study, surficial sediment chlorophyll-a was quantified in late spring at 20–50 locations throughout Chesapeake Bay for 8 years (1993–2000). A model was developed to estimate chlorophyll-a deposition to sediments using these measurements, while accounting for chlorophyll-a degradation during the time between deposition and sampling. Carbon flux was derived from these estimates via C:chl-a = 75.Bay-wide, the accumulation of chlorophyll-a on sediments by late spring averaged 171 mg m−2, from which the chlorophyll-a and carbon sinking fluxes, respectively, were estimated to be 353 mg m−2 and 26.5 gC m−2. These deposition estimates were ∼50% of estimates based on a sediment trap study in the mid-Bay. During 1993–2000, the highest average chlorophyll-a flux was in the mid-Bay (248 mg m−2), while the lowest was in the lower Bay (191 mg m−2). Winter–spring average river flow was positively correlated with phytoplankton biomass in the lower Bay water column, while phytoplankton biomass in that same region of the Bay was correlated with increased chlorophyll-a deposition to sediments. Responses in other regions of the Bay were less clear and suggested that the concept that nutrient enrichment in high flow years leads to greater phytoplankton deposition to sediments may be an oversimplification. A comparison of the carbon flux associated with the deposition of the spring bloom with annual benthic carbon budgets indicated that the spring bloom did not contribute a disproportionately large fraction of annual carbon inputs to Chesapeake Bay sediments. Regional patterns in chlorophyll-a deposition did not correspond with the strong regional patterns that have been found for plankton net community metabolism during spring. 相似文献
16.
象山港水体的磷酸盐及其对赤潮的潜在影响 总被引：1，自引：0，他引：1
根据2012年5月和2017年10月在象山港海域的调查结果，研究了象山港磷酸盐的来源、分布和消耗。磷酸盐浓度在两次的调查中均呈现由港顶向湾口逐渐降低的趋势，说明港顶区有较高浓度磷酸盐的输入，可能主要来自生活污水和海水养殖。磷酸盐、硝酸盐和盐度在象山港外湾的分布特征说明长江和钱塘江是外湾水体磷酸盐的一个重要来源；此外，磷酸盐、硝酸盐和盐度在牛鼻山水道和佛渡水道的差异分布说明，陆地径流可能经由佛渡水道向象山港贡献了一部分的磷酸盐。内湾水体的磷酸盐分布受控于内外湾水体混合和浮游植物的同化作用，磷酸盐在水体停留时间较长的内湾发生了明显的消耗，相比于保守混合模型的估算值，磷酸盐在象山港内湾中的净消耗比例在2012年5月和2017年10月分别约为20%和9%。2017年秋季观测到的磷酸盐浓度[（1.88±0.31）μmol/L]与2002-2005年在同季节观测到的结果相比增加超过了50%，N/P值下降明显，这一变化可能会导致象山港内引发藻华的藻类种群发生变化，同时也可能会引发更为严重的赤潮。 相似文献
17.
浮游植物是水生生态系统的基础生产者, 其群落结构直接影响到生态系统的健康和安全。河流输入是人类活动影响大亚湾水体环境最重要的途径之一, 淡水输入改变了水体温度、盐度、浊度和营养盐等环境因子, 对浮游植物群落结构产生影响。文章调查研究了2015年河流输入最强的夏季丰水期大亚湾的水体环境因子和浮游植物群落结构, 分析了在较强河流输入影响下浮游植物群落结构的动态变化及其对环境因子的响应。结果发现, 夏季大亚湾淡澳河的输入使湾顶淡澳河口区域形成层化的低盐、高温、低透明度、高营养盐的水体, 湾中部表层水体则受一定强度河流羽流影响, 而湾口和湾中部底层水体主要受外海水影响。淡澳河淡水输入是夏季大亚湾外源性氮、磷营养盐的主要来源, 而硅酸盐除河流输入外, 外海水也输入较多的营养盐使得底层水体硅酸盐浓度较高。夏季大亚湾水体营养比例失衡较严重, 溶解无机磷是限制浮游植物生长的重要因子。硅藻是大亚湾夏季浮游植物的优势类群, 调查发现3种优势种[极小海链藻(Thalassiosira minima)、中肋骨条藻(Skeletonema costatum)和圆海链藻(Thalassiosira rotula)]均为硅藻。通过聚类分析, 可将大亚湾夏季浮游植物群落主要分为3种类型, 分别为: 浮游植物丰度较大的极小海链藻藻华暴发的群落, 位于淡澳河口, 受河流输入影响明显; 中肋骨条藻占据优势的群落, 分布在受一定强度的河流及其羽流影响的湾顶和湾中部区域; 浮游植物丰度较低的群落, 无明显优势种, 主要分布在湾口海水影响区域。淡澳河口的水体环境有利于小型链状硅藻极小海链藻的快速繁殖并暴发了藻华, 藻华发生时的海水环境条件为: 温度30~31°C, 盐度17‰~31‰, 水体透明度0.45~1.2m。硅藻对不同营养盐利用的差异以及随后的生物碎屑和颗粒沉降过程导致藻华发生区域Si∶N值略降低, N∶P值显著升高。河流输入影响下, 单一物种大量生长使得浮游植物群落种类组成丰度分布极不均匀, 从而导致淡澳河口浮游植物群落的种类多样性和均匀度指数降低, 种类多样性和均匀度指数均从淡澳河口向湾口逐渐增大。 相似文献
18.
渤海湾天津近岸海域初级生产力及网采浮游植物种类组成 总被引：2，自引：0，他引：2
于2012至2013年调查了渤海湾天津近岸海域的初级生产力和网采浮游植物种类组成。2012—2013年春季调查海域初级生产力为2.20～23.18 mgC/(m2·d),平均值为9.54 mgC/(m2·d),高值区主要分布在塘沽附近海域;夏季初级生产力为6.37～138.37 mgC/(m2·d),平均值为44.13 mgC/(m2·d),高值区主要分布在北塘和汉沽附近海域。与1982—1983年和1992—1993年同期调查结果相比,近30 a来渤海湾初级生产力呈下降趋势。网采浮游植物经初步分析发现2门59种(包括未定名种),其中硅藻49种,占种类组成的83.1%;甲藻10种,占种类组成的16.9%;优势种主要为柔弱根管藻Rhizosolenia delicatula、布氏双尾藻Ditylum brightwellii、中华盒形藻Bidduiphia sinensis、中肋骨条藻Skeletonema costatum、旋链角毛藻Chaetoceros curvisetus、尖刺菱形藻Nitzschia pungens、丹麦细柱藻Leptocylindrus danicus和浮动弯角藻Eucampia zoodiacus。调查海域春季浮游植物细胞丰度为3.32×103～3.85×107 cell/m3,夏季为2.48×106～4.65×109 cell/m3,夏季明显高于春季;从分布上看,北部和南部的浮游植物细胞丰度高于中部,主要是由天津近岸海域河流分布造成。浮游植物多样性指数在春季和夏季的均值分别为1.865和1.560。2012—2013年浮游植物细胞丰度及其分布主要与水深、化学需氧量、pH值、溶解氧和无机磷相关性较大。 相似文献
19.
《Deep Sea Research Part I: Oceanographic Research Papers》2002,49(8):1431-1444
Observations during a spring phytoplankton bloom in the northeast Atlantic between March and May 1992 in the Biotrans region at 47°N, 20°W, are presented. During most of the observation period there was a positive heat flux into the ocean, winds were weak, and the mixed layer depth was shallow (<40 m). Phytoplankton growth conditions were favourable during this time. Phytoplankton biomass roughly doubled within the euphotic zone over the course of about 7 days during mid-April, and rapidly increased towards the end of the study until silicate was depleted. However, the stratification of the water column was transient, and the spring bloom development was repeatedly interrupted by gales. During two storms, in late March and late April, the mixed-layer depth increased to 250 and 175 m, respectively. After the storm events significant amounts of chlorophyll-a, particulate organic carbon and biogenic silica were found well below the euphotic zone. It is estimated that between 56% and 65% of the seasonal new production between winter and early May was exported from the euphotic zone by convective mixing, in particular, during the two storm events. Data from the NABE 47°N study during spring 1989 are re-evaluated. It is found that convective particle export was of importance during the early part of that bloom too, but negligible during the height of the bloom in May 1989. The overall impact of convective particle export during spring 1989 was equivalent to about 36% of new production. In view of these and previously published findings it is concluded that convective transport during spring is a significant process for the export of particulate matter from the euphotic zone in the temperate North Atlantic. 相似文献
20.
The effects of spring-neap tide on the phytoplankton community development in the Jiaozhou Bay, China 总被引：7，自引：4，他引：3
The development of the phytoplankton community was studied in the Jiaozhou Bay during the spring to neap tide in August 2001, through three cruises and a 15 d continuous observation. This investigation indicates that diatom cell abundance increased sharply following the end of a spring tide, from 9 cells/cm^3 to a peak of 94 cells/cm^3. The dominant species composition and abundance show a quick species sequence from spring to neap tide, and the dominant species at the start phase is Skeletomena costatum, then changes to Chaetoceros curvisetus, finally it changes to Eucampia zodiacus. Silicate concentration increases during spring tide, as a result of nutrient replenishment from the water-sediment interface, its initial average concentration in neap tide is 1.39μmol/dm^3 and reached the peak average concentration of 8.40μmol/dm^3 in spring tide. But the nitrogen concentration dropped due to dilution by the low nitrogen seawater from the Huanghai Sea, its initial average concentration in neap tide is 67μmol/dm^3 and decreased to the average concentration of 54μmol/dm^3 in spring tide. The degree of silicon limitation was decreased and phytoplankton, especially diatoms, responds immediately after nutrient replenishment in th ewater column. Skeletonmea costatum, as one of the dominant species in the Jiaozhou Bay, shows a quicker response to nutrient availability than Eucampia zodiacus and Chaetoceros curvisetus. It is proposed that dominant species composition and water column stability synchronously determine the development of phytoplankton summer blooms in the Jiaozhou bay. 相似文献