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1.
According to the principle of photosythesis with sunlight and CO2 by phytoplankton supplying food for marine organisms, while the nitrogenous compounds excreted by marine animals are transferred by bacteria into the nitrate for the use of phytoplankton, an artificial microhabitat is built to investigate comprehensively distributive relationship of 127Cs, 134Cs, 65Zn, 60Co, 50Fe, 54Mn In the parts of the microhabitat. The results show that 78% of the 134Cs and 137Cs in ion state are present in sea water, with 28 % of them nearly homogenous envolved in the exchanging processes of the suspensates and organisms, and that 80% of 59Fe, 54Mn, 65Zn, 60Co were concentrated by solid substance, whose motion was mainly controlled by biological processes. The factors affecting the distribution of nuclides in each composition are discussed. As another type of research on the controlled ecological system which is a subject currently studied in the world, the present paper is of reference value for studying quantitativ  相似文献   

2.
Natural colloids are abundant in seawater and are an intermediary in the fate, transport and bioavailability of many trace elements. Knowledge of the pathways and mechanisms of the biological uptake of colloidal Fe and other Fe species is of paramount importance in understanding Fe limitation on marine phytoplankton and thus carbon sequestration in the ocean. Whether the natural colloids serve as a source for the biological Fe requirements of marine phytoplankton, or just as a sink for particle-reactive metals in the oceans remains largely unknown. This study examined the bioavailability of Fe bound with colloids from different regions to a coastal diatom (Thalassiosira pseudonana). Natural colloids were isolated by cross-flow ultrafiltration and radiolabeled with 59Fe before being exposed to phytoplankton. Control experiments were conducted to ensure that 59Fe radiolabeled onto the colloids remained mostly in the colloidal phase. Both the natural oceanic and coastal colloidal organic matter complexed Fe (1 nm–0.2 μm) can be biologically available to the marine diatom even though its uptake was lower than the low molecular weight counterparts. By comparing the measured Fe internalization fluxes and the calculated maximum diffusive uptake fluxes, it is evident that ligand exchange kinetics on the cell surface may control the internalization of macromolecular Fe. The calculated concentration factors under dark and light conditions were generally comparable. Colloidal Fe, as an important intermediary phase, can be actively involved in the planktonic food web transfer through biological uptake and regeneration processes. The bioavailable fraction of Fe may be substantially underestimated by only considering the truly dissolved Fe or overestimated when using the external fluxes, such as aerosol Fe, as the bioavailable fraction.  相似文献   

3.
研究了南麂列岛海洋自然保护区浮游植物物种组成、数量分布、多样性指数及其与营养盐、浮游动物的关系.经鉴定,共发现浮游植物86种,隶属于33属.网样浮游植物平均密度为194.00×104个/m3,水样浮游植物平均密度为4.98×104个/m3,优势类群有角毛藻(Chaetoceros sp.)、角藻(Ceratuym sp.)、中肋骨条藻(Skeletonema costatum)、红色裸甲藻(Akashiwo sanyuineum)等.网样浮游植物多样性平均指数为2.28,水样浮游植物多样性平均指数为2.17.根据浮游植物组成特点,将其分为两个生态类群:近岸性和广布性类群,外海性类群.  相似文献   

4.
唐松 《海洋科学》2010,34(7):34-40
借助"中国首次环球科学考察航次",在印度洋海区进行了N、Fe、N+Fe以及N+Fe+P的营养盐添加模拟实验。通过对实验过程中水体营养盐浓度、叶绿素a(Chl-a)浓度以及温度等参数进行分析,探讨了添加不同营养盐对该实验海区浮游植物生长的影响。结果表明,N的添加会引起浮游植物的快速爆发,而单独添加Fe并不能刺激浮游植物快速生长,N、P联合作用对浮游植物生长的影响远远大于单独N的作用。另外,在实验海区浮游植物优先利用海水中的硝酸盐,在硝酸根耗尽后,海水中可被利用的P会促进浮游植物的生长。实验过程中水体N/P比值的变化同叶绿素a浓度以及浮游植物生长速度(R)没有可对比性,而且N/P比值与后两者之间的相关性都差,所以认为水体中N/P比值并不能单独决定浮游植物生长。此外,实验水体温度同Chl-a浓度和R值之间相关性分析表明,水体温度虽对浮游植物生长有重要作用,但不能控制浮游植物生长。  相似文献   

5.
The solubility of iron in oxic waters is so low that iron can be a limiting nutrient for phytoplankton growth in the open ocean. In order to mimic low iron concentrations in algal cultures, Ethylenediaminetetraacetate (EDTA) is commonly used. The presence of EDTA enables culture experiments to be performed at a low free metal concentration, while the total metal concentrations are high. Using EDTA provides for a more reproducible medium. In this study Fe speciation, as defined by EDTA in culture media, is compared with complexation by natural organic complexes in ocean water where Fe is thought to be limited. To grow oceanic species into iron limitation, a concentration of at least 10−4 M EDTA is necessary. Only then does the calculated [Fe3+] concentrations resemble those found in natural sea water, where the speciation is governed by natural dissolved organic ligands at nanomolar concentrations. Moreover, EDTA influences the redox speciation of iron, and thus frustrates research on the preferred source of Fe-uptake, Fe(III) or Fe(II), by algae. Nowadays, one can measure the extent of natural organic complexation in sea water, as well as the dissolved Fe(II) state, and can use ultra clean techniques in order to prevent contamination. Therefore, it is advisable to work with more natural conditions and not use EDTA to create iron limitation. This is especially important when the biological availability of the different chemical fractions of iron are the subject of research. Typically, many oceanic algae in the smallest size classes can still grow at very low ambient Fe and are not easily cultivated into limitation under ambient sea water conditions. However, the important class of large oceanic algae responsible for the major blooms and the large scale cycling of carbon, silicon and other elements, commonly has a high Fe requirement and can be grown into Fe limitation in ambient seawater.  相似文献   

6.
Origin of sedimentary organic matter in the north-western Adriatic Sea   总被引：1，自引：0，他引：1  
In order to evaluate the origin and the transformation of organic matter on the shallow shelf of the NW Adriatic Sea, organic carbon, total nitrogen and stable isotope ratios of organic carbon were analysed in riverine suspended matter and sediments as well as in marine suspended and sedimentary organic matter, in marine phytoplankton and zooplankton.The deposition of organic matter is influenced by fine sediment concentration. Surface sediments were characterised by highly variable biogeochemical conditions on the sea floor, whereas sub-surface sediments showed a more homogeneous hypoxic/anoxic environment.Low Corg/N ratio and high organic carbon and nitrogen concentrations in riverine suspended organic matter indicate an important contribution of freshwater phytoplankton within rivers, particularly during low flow regimes, which adds to the marine phyto- and zooplankton at shelf locations.In order to evaluate the importance of terrestrial, riverine and marine sources of OM in shelf sediments, a three end-member mixing model was applied to shelf surface sediments using 13C/12C values for organic matter and N/C ratios. The model showed an elevated contribution of terrestrial organic substances at intermediate depths (10–15 m), mostly corresponding to an area of coarser grain-size, whereas the riverine and marine organic fractions were mainly accumulating near the coast and offshore, respectively.  相似文献   

7.
Further studies on the transport in sea water and accumulation in marine sediment of the radionuclides, released from a nuclear power plant, on Urazoko Bay, Fukui Prefecture were reported.The partition of radionuclides among the particle size fractions of a sediment sample indicated that the accumulation of60Co,137Cs and54Mn in the sediment were dominated substantially by the sorption on the particle surface in sea water, and the patterns of their sorption were considerably similar to each other.In regard to the60Co contamination of marine sediments in an area of about 13 km2 around the nuclear power plant, 60% of the60Co contamination were retained in Urazoko Bay, which occupies only 7% of the bottom surface of the region.It is clear that a part of60Co accumulated in the sediment of Urazoko Bay gradually moved to the outerward.  相似文献   

8.
This article summarizes the author's work on210Pb and210Po distributions in the marine environment for which the Okada Prize of the Oceanographical Society of Japan was awarded. In this review, the work of other investigators and the studies now going on are also included. The210Pb concentration in the surface water of the ocean is controlled by the atmospheric flux of210Pb and productivity. The disequilibrium between226Ra and210Pb in the deep sea reveals that the oceanic residence time of lead is less than a hundred years rather than of the order of thousands of years as thought before based on stable lead measurement in ocean water. Particulate removal of210Pb from the water column is likely to be the major cause of the deficiency of210Pb in the water, however more investigations would be needed to clarify the detailed removal mechanism of210Pb. The experiments on particulate flux by using sediment traps will provide an unique opportunity to examine this. 210Pb in excess of226Ra in sediment is useful for geochronology of shallow water sediments and the study on bioturbation rates on the deep sea sediments.  相似文献   

9.
Chlorophyll-a (chl-a) concentration has an important economic effect in coastal and marine environments on fisheries resources and marine aquaculture development. Monthly climatologies the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) derived chl-a from February 1998 to August 2004 around Funka Bay were used to investigate the spatial and temporal variability of chl-a concentrations. SeaWiFS-derived suspended sediment, MODIS derived sea surface temperature (SST), solar radiation and wind data were also analyzed. Results showed two distinct chlorophyll blooms in spring and autumn. Chl-a concentrations were relatively low (<0.3 mg m−3) in the bay during summer, with high concentrations occurring along the coast, particularly near Yakumo and Shiraoi. In spring, chl-a concentrations increased, and a large (>2 mg m−3) phytoplankton bloom occurred. The spatial and temporal patterns were further confirmed by empirical orthogonal function (EOF) analysis. About 83.94% of the variability could be explained by the first three modes. The first chl-a mode (77.93% of the total variance) explained the general seasonal cycle and quantified interannual variability in the bay. The spring condition was explained by the second mode (3.89% of the total variance), while the third mode (2.12% of the total variance) was associated with autumn condition. Local forcing such as the timing of intrusion of Oyashio water, wind condition and surface heating are the mechanisms that controlled the spatial and temporal variations of chlorophyll concentrations. Moreover, the variation of chlorophyll concentration along the coast seemed to be influenced by suspended sediment caused by resuspension or river discharge.  相似文献   

10.
The area of Arctic sea ice has dramatically decreased, and the length of the open water season has increased;these patterns have been observed by satellite remote sensing since the 1970 s. In this paper, we calculate the net primary productivity(NPP, calculated by carbon) from 2003 to 2016 based on sea ice concentration products,chlorophyll a(Chl a) concentration, photosynthetically active radiation(PAR), sea surface temperature(SST), and sunshine duration data. We then analyse the spatiotemporal changes in the Chl a concentration and NPP and further investigate the relations among NPP, the open water area, and the length of the open water season. The results indicate that(1) the Chl a concentration increased by 0.025 mg/m~3 per year;(2) the NPP increased by 4.29 mg/(m~2·d) per year, reaching a maximum of 525.74 mg/(m~2·d) in 2016; and(3) the Arctic open water area increased by 57.23×10~3 km~2/a, with a growth rate of 1.53 d/a for the length of the open water season. The annual NPP was significantly positively related to the open water area, the length of the open water season and the SST.The daily NPP was also found to have a lag correlation with the open water area, with a lag time of two months.With global warming, NPP has maintained an increasing trend, with the most significant increase occurring in the Kara Sea. In summary, this study provides a macroscopic understanding of the distribution of phytoplankton in the Arctic, which is valuable information for the evaluation and management of marine ecological environments.  相似文献   

11.
The downward flux of Mn through the water column was directly measured using sediment traps. The Mn flux from the bottom sediment to the water column, and the removal rate of Mn in the bottom water were estimated from Mn gradients in the bottom water. The sediment traps were deployed more than ten times at the same station in Funka Bay, Japan. The trapped settling matter and filtered suspended matter samples were analyzed for Mn, Fe, Al and ignition loss. The observed downward flux of Mn through the water column in winter (1.3–2.8 μg/cm2 /day) was generally an order of magnitude larger than that in summer (0.13–0.45 μg/cm2 /day), and the Mn fluxes for both seasons were also greater than the accumulation rate of Mn in the bottom sediments (0.10 μg/cm 2/day). More Al was contained in the trapped settling matter than in the suspended matter, while Mn showed the opposite behavior. The Fe/Mn ratio of the residual fraction (obtained by subtracting the sediment component of the settling matter) was rather well correlated with the corresponding ratio in suspended matter. Settling particles are expected to scavenge suspended matter during their passage through the water column. The flux of Mn across the sediment—water interface was estimated from its vertical profiles in the water column to be 0.1–0.3 μg/cm2 day. The residence time of Mn in bottom water was about one to several months. These results suggest that Mn is actively recycled between the water column and the sediments of the coastal sea.  相似文献   

12.
Coastal marine sediment, air and seawater samples were collected at six sampling stations in the Eastern Mediterranean Sea distant from pollutant point sources. All sediment samples were analyzed to determine polycyclic aromatic hydrocarbon (PAH), black carbon (BC) and organic carbon (OC) contents. The PAH contents of gaseous and seawater samples of the study were determined in order to evaluate the role of air–sea exchange as PAH nonpoint source to the marine sediments. The average concentration of the total PAHs (∑PAHs) in the sediments varied from 2.2 to 1056.2 ng g−1 dry weight. The average BC and OC contents varied from 0.3 to 5.6 and from 2.9 to 21.4 mg g−1 dry weight, respectively. ∑PAH concentration in the marine atmosphere varied from 20.0 to 83.2 ng m−3. Air–water exchange flux (FA–W) estimation has indicated air transport as a significant source of PAHs to pristine marine sediments of Eastern Mediterranean. In addition, the significant correlation between the PAHs and the organic and soot carbon content further suggests the importance of atmospheric input of PAHs to the sediments.  相似文献   

13.
I present here a review of my work concerning nitrogen assimilation by marine phytoplankton. This opportunity was provided to me as the recipient of the Okada Prize for 1990 from the Oceanographical Society of Japan. Assimilation of nitrogenous nutrients by phytoplankton has received considerable research effort since it is an essential process in organic matter production in the sea surface. The use of15N technique is necessary for tracing nitrogen assimilation by natural marine phytoplankton, but nitrogen metabolism of heterogenous natural populations significantly complicates flow of isotope. Dilution of15N isotope by heterotrophic regeneration of ammonium causes underestimates of uptake rates. I made an evaluation of isotope dilution effects in available data sets of15N-ammonium uptake experiments in literature. Incorporated15N in particulates might revert back to dissolved organic or inorganic nitrogen. I conducted pulse-chase experiments which can quantify such loss of tracer. From these studies, a short term experiment with sufficient amount of tracer enrichment is found to overwhelm these problems. In such an experiment, however, the elevation of nutrient concentration by tracer addition may likely perturb the uptake process. An initial rapid uptake is expected if the population is nitrogen deficient, but I found that this phenomenon is not common to surface oligotrophic open oceans. Uptake rate from such an experiment, or capacity of nitrogen uptake, was obtained using surface waters from an extended area in the North Pacific, and its regional variability was discussed. In addition to overall15N uptake, time series analysis of intracellular15N partitioning between hot ethanol soluble and insoluble fractions was found to be useful. When15N-ammonium is added to nitrogen deficient cells of phytoplankton,15N is accumulated in the ethanol soluble fraction. Using cultured strains of marine phytoplankton, this accumulation was proved to be caused by the difference of rates of nitrogen uptake and nitrogenous macromolecule synthesis. Uptake rate per cell is relatively constant irrespective of nutritional status, but macromolecule synthesis decreases with nitrogen deficiency. This accumulation of15N in the ethanol soluble fraction was used as an index of nutritional status with respect to nitrogen of the natural populations of phytoplankton from the western North Pacific. The uptake capacity of nitrate was observed to be higher than that of ammonium in the regional upwelling around Izu Islands and during the spring bloom in Alaskan coastal water. The15N partitioning technique revealed that nitrate taken up was rapidly incorporated in the macromolecule fraction. This suggests that ammonium uptake is suppressed to be smaller than intracellular nitrogen assimilation, rather than that nitrate is taken up in excess and accumulates within the cell. Regulation of nitrate uptake by light intensity was also discussed in detail for the Alaskan data. Several other studies currently conducted are also mentioned.  相似文献   

14.
夏季浙江沿岸陆架区泥沙输运机制   总被引：3，自引：0，他引：3  
陈斌  高飞  刘健 《海洋学报》2017,39(3):96-105
基于2014年夏季浙江沿岸陆架区的水文、泥沙、底质沉积物等实测资料,运用物质通量分析方法和Gao-Collins粒径趋势分析法,探讨了泥沙的输运通量、输运方向、动力机制及净输运趋势。夏季,近岸含沙量规律性较强,由西至东逐渐降低,由南至北逐渐升高,且与潮流有非常好的对应关系,呈现出明显的潮周期变化特征。研究区净悬沙通量自岸向外海迅速变小,悬沙输运中平流输运占主导地位,其次是垂向净环流对悬沙输运的影响,近岸海域表现为向海输沙,30 m以深海域表现为东北向输沙,同时台湾暖流的屏障作用也影响了悬沙向海扩散。粒径趋势分析显示浙江沿岸陆架表层沉积物的长期输运机制为由东北向西南输运,在流系以及海底地形的影响下,中部海域出现粒径趋势较弱的沉积中心。而在夏季,悬浮泥沙主要为平行岸线向东北输运,估算每天进入研究海域的净悬浮泥沙约为1.9×106 t。  相似文献   

15.
South of Hangzhou Bay, Zhejiang Province, exhibits an embayed muddy coastline, with the muddy beaches of embayments extending continuously seaward.The source of sediments on this coast presents an interesting problem to marine geologists and geomorphologists .The total annual load of sediments from the rivers of Zhejiang is only 12×106t.These materials affect only the area near the river mouths. The paper showed that the sediment along the coast of Zhejiang mainly comes from the Changjiang Estuary through analysing the time and space variations of suspended sediment, the features of sediment and the sedimentary transport.The Changjiang River is the largest river system in China, its sediment to the sea amounting to 468×106t. The sediment during summer transports mainly eastward, and is affected by the water body with high temperature, salinity and transparency; the winter season is the period with high sediment concentration. The sediment of the Changjiang Estuary transports together with the longshor  相似文献   

16.
1996年春季副热带环流区浮游植物生态的初步研究   总被引：3，自引：0，他引：3  
鉴定浮游植物种类54属184种(含变种和变型),其中暖水种为140种(占76.5%).硅藻类和甲藻类等浮游植物的平均总细胞密度为198.71×102个/m3;蓝藻类藻丝体平均密度为44.55×102条/m3.浮游植物各类别的分布与水域的磷酸盐含量、黑潮以及其他水系(涌升水和沿岸水等)等相关;蓝藻类的束毛藻(Trichodesmium)的分布还与50m以浅水体的平均水温关系密切.  相似文献   

17.
Phytoplankton biomass, taxonomy, primary productivity, and photosynthetically available radiation (PAR) were studied as part of baseline data collection for prospective nodule mining in the Central Indian Basin during the ORV Sagar Kanya cruise SK-120 in January 1997. The phytoplankton cell counts and chlorophyll a estimates showed low biomass level, suggesting low rates of primary productivity in the region studied. The average chlorophyll a value was 0.775 mg m?3 at surface and 17.75 mg m?2 in the water column. Similarly, average primary productivity at surface was 3.72 mg C m?3 d?1 and was 51.23 mg C m?2 d?1 in column. The chlorophyll a maxima at 50 to 80 m was the characteristic feature of the euphotic zones of the area. Average phytoplankton counts at the surface were low (3960 cells/l), compared to those at 25 m (6421 cells/l) and 75 m (5187 cells/l). At most of the stations mesozooplankton biomass was maximum in the top 50 m water column, indicating the importance of grazing in the euphotic zone. Appreciable quantities of mesozooplankton were observed below the euphotic zone, where settlement of chlorophyll a occurs. The low iron concentration in the water and its relationship with the water column productivity were correlated. The results show that waters in the CIB have low productivity in the surface as well as subsurface layers. This is expected to change in this case of a mining discharge in to these layers, possibly locally affecting the existing marine ecosystems. The final impact of such mining activity may remain negligible in the deep sea environment.  相似文献   

18.
Alterations in sea ice and primary production are expected to have cascading influences on the food web in high Arctic marine ecosystems. This study spanned four years and examined the spring phytoplankton production bloom in Disko Bay, West Greenland (69°N, 53°W) (using chlorophyll a concentrations as a proxy) under contrasting sea ice conditions in 2001 and 2003 (heavy sea ice) and 2002 and 2004 (light sea ice). Satellite-based observations of chlorophyll a, sea ice and sea surface temperature were used together with in situ depth profiles of chlorophyll a fluorescence collected at 24 sampling stations along the south coast of Disko Island (5-30 km offshore) in May 2003 and 2004. Chlorophyll a and sea surface temperatures were also obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS: EOS-Terra and AQUA satellites) between March 2001 and July 2004. Daily SMMR/SSMI sea ice data were obtained in the same years. An empirical regional algorithm was developed to calibrate ratios of remotely sensed measurements of water leaving radiance with in situ chlorophyll a fluorescence. The optimal integration depth was 0-4 m, explaining between 70% and 91% of the variance. The spatial development of the phytoplankton bloom showed that the southwestern corner of the study area had the earliest and the largest spring phytoplankton bloom. The eastern part of Disko Bay, influenced by meltwater outflow from the glaciers, shows no signs of an early phytoplankton bloom and followed the general pattern of an accelerated bloom soon after the disappearance of sea ice. In all four years the coupling between phytoplankton and sea ice was bounded by average open water between 50% and 80%, likely due to the combined availability of light and stable open water. The daily incremental growth in both mean chlorophyll a density (chlorophyll a per volume water, μg l−1) and abundance (density of chlorophyll a extrapolated to ice free areas, tons) estimated by linear regression (chlorophyll a vs. day) between 1 April and 15 May was highest in 2002 and 2004 (light ice years) and lowest in 2001 and 2003 (heavy ice years). In years with late sea ice retreat the chlorophyll a attained only slightly lower densities than in years with early sea ice retreat. However, the abundance of chlorophyll a in light ice years was considerably larger than in heavy ice years, and there was an obvious effect of more open water for light-induced stimulation of primary production. This observation demonstrates the importance of estimating chlorophyll a abundance rather than density in sea ice covered areas. This study also presents the first regional calibration of MODIS chlorophyll a data for Arctic waters.  相似文献   

19.
The temporal and spatial distribution of total and organic particulate matter is investigated in the Bideford River estuary. Particulate matter is homogenously distributed in both the water column and the surface sediment, due to high rates of resuspension and lateral transport. The measured mean sedimentation rate for the estuary is 183·5 g of particulate matter m?2 day?1, of which more than half is due to resuspension.The surface sediment of the estuary is quantitatively the dominant reservoir of organic matter, with an average of 902·5 g of particulate organic carbon (POC) m?2 and 119·5 g of particulate organic nitrogen (PON) m?2. Per unit surface area, the sediment contains 450 times more POC and 400 times more PON than the water column. Terrestrial erosion contributes high levels of particulate matter, both organic and inorganic, to the estuary from the surrounding watershed. Low rates of sediment export from the estuary result in the accumulation of the terrigenous material. The allochthonous input of terrigenous organic matter masks any relationship between the indigenous plant biomass and the organic matter.In the water column, a direct correlation exists between the organic matter, i.e. POC and PON, concentration and the phytoplankton biomass as measured by the plant pigments. Resuspension is responsible for the residual organic matter in the water column unaccounted for by the phytoplankton biomass.The particulate content of the water column and the surface sediment of the estuary is compared to that of the adjacent bay. Water-borne particulate matter is exported from the estuary to the bay, so that no significant differences in concentration are noted. The estuarine sediment, however, is five to six times richer in organic and silt-clay content than the bay sediment. Since sediment flux out of the estuary is restricted, the allochthonous contribution of terrigenous particulate matter to the bay sediment is minor, and the organic content of the bay sediment is directly correlated to the autochthonous plant biomass.  相似文献   

20.
The high nutrient concentration associated with the mixing dynamics of two warm and cold water masses supports high primary production in the Yellow Sea. Although various environmental changes have been reported, no recent information on small phytoplankton contribution to the total primary production as an important indicator for marine ecosystem changes is currently available in the Yellow Sea. The major objective of this study is to determine the small (< 2 μm) phytoplankton contribution to the total primary production in the Yellow Sea during August, 2016. In this study, we found relatively lower chlorophyll a concentrations in the water column than those previously reported in the central waters of the Yellow Sea. Moreover, the overall contribution of small phytoplankton (53.1%) to the total chlorophyll a concentration was considerably higher in this study than that (10.7%) observed previously. Based on the N/P ratio (67.6 ± 36.6) observed in this study, which is significantly higher than the Redfield ratio (16), we believe that phytoplankton experienced P-limiting conditions during the study period. The average daily carbon uptake rate of total phytoplankton in this study was 291.1 mg C m-2 d-1 (± 165.0 mg C m-2 d-1) and the rate of small phytoplankton was 205.7 mg C m-2 d-1 (± 116.0 mg C m-2 d-1) which is 71.9% (± 8.8%) of the total daily carbon uptake rate. This contribution of small phytoplankton observed in this study appears to be higher than that reported previously. Our recent measured primary production is approximately 50% lower than the previous values decades ago. The higher contributions of small phytoplankton to the total chlorophyll a concentration and primary production might be caused by P-limited conditions and this resulted in lower chlorophyll a concentration and total primary production in this study compared to previous studies.  相似文献   

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