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1.
A study was carried out to investigate the grazing pressure of heterotrophic nanoflagellates(HNF) on bacteria assemblages in the Yellow Sea Cold Water Mass(YSCWM) area in October, 2006. The results show that the HNF abundance ranges from 303 to 1 388 mL-1, with a mean of 884 mL-1. The HNF biomass is equivalent to 10.6%–115.6% of that of the bacteria. The maximum abundance of the HNF generally occurred in the upper 30 m water layer, with a vertical distribution pattern of surface layer abundance greater than middle layer abundance, then bottom layer abundance. The hydrological data show that the YSCWM is located in the northeastern part of the study area, typically 40 m beneath the surface. A weak correlation is found between the abundances of HNF and bacteria in both the YSCWM and its above water layer. One-way ANOVA analysis reveals that the abundance of HNF and bacteria differs between inside the YSCWM and in the above water mass. The ingestion rates of the HNF on bacteria was 8.02±3.43 h-1 in average. The grazing rate only represented 22.75%±6.91% of bacterial biomass or 6.55%+4.24% of bacterial production, implying that the HNF grazing was not the major factor contributing to the bacterial loss in the YSCWM areas.  相似文献   

2.
Shelf-basin advection is essential to subsistence of the Arctic copepod Calanus hyperboreus population in high basin area. Its abundance, population structure and body size in pelagic layer were investigated with samples collected over a large range in the western Arctic Ocean during summer 2003, to evaluate the geographical variation in recruitment pattern. Calanus hyperboreus was absent from the shallow areas of the Chukchi Sea and most abundant in the slope area between the Chukchi Sea and Chukchi Abyssal Plain(CS-slope). Total abundance varied between 1 110.0 and 5 815.0 ind./m2 in the CS-slope area and ranged from 40.0 to 950.0 ind./m2 in the other areas. Early stages(CI–IV) dominated in the CS-slope area, whereas CV and adult females were frequently recorded only in deep basin areas. Geographical difference of prosome length was most evident in CIII,with average ranging from 2.48 to 2.61 mm at the CS-slope stations and 2.16–2.37 mm at the others. Abundance of early developmental stages(CI–CIV) correlated positively with Chl a concentration, but negative correlation was observed in late stages(CV–adult). Our results indicated that C. hyperboreus can benefit from primary production increase through accelerated development in the first growth season and the productive CS-slope area is a potential source for slope-basin replenishment.  相似文献   

3.
Sediment core samples were collected from 17 stations in the middle and eastern Chukchi Sea during the sixth Chinese National Arctic Research Expedition(CHINARE-Arctic) in summer 2014.The samples were analyzed for composition,abundance,biomass,vertical distribution,size spectra,and ecological indexes of meiofauna.A total of 14 meiofauna taxa were detected,and the free-living marine nematodes comprised the most dominant taxon,accounting for 97.21% of the average abundance.The abundance and biomass of meiofauna were within ranges of(218.12±85.83)-(7 239.38±1 557.15) ind./(10 cm~2) and(130.28±52.17)-(3 309.56±1 751.80) μg/(10 cm~2),with average values of(2 391.90±1 966.19) ind./(10 cm~2) and(1 549.73±2 042.85) μg/(10 cm~2)(according to dry weight)respectively.Furthermore,91.26% of the individuals were distributed in the top layer of 0-5 cm of surface sediment,and 90.84% had sizes of 32-250 μm.Group diversity index of meiofauna in the survey area was low,and the variation of abundance was the main difference in meiofauna communities among all stations.Abundance and biomass of meiofauna were not significantly correlated with environmental factors except concentration of nutrient Si in bottom seawater.Abundance of meiofauna in shallow water of marginal seas in the Pacific sector of the Arctic Ocean is likely at a same level and higher than that in most of China sea areas,suggesting that the shallow water of the summer Chukchi Sea is a continental shelf area with rich resources of meiofauna.The Chukchi Sea is important for studying the ecosystem of the Arctic Ocean and environmental responses.However,studies on meiofauna in the Chukchi Sea are still not enough,and in the future,natural and human disturbances may increase due to global warming,the Arctic channel opening,and other factors.Thus,more studies on meiofauna should be required,in order to know more about how the Arctic benthic community would alter.  相似文献   

4.
中尺度涡影响下的南海西部活性铝分布   总被引：1，自引：0，他引：1  
To understand the distribution of aluminum(Al) under the influence of mesocale eddies in the western South China Sea(SCS), sea level anomaly, geostrophic current, environmental parameters and reactive Al were investigated in the western SCS in August 2013. The highest reactive Al concentration((180±64) nmol/L) was observed in the surface waters, indicating a substantial atmospheric input. Vertically, the reactive Al decreased from the surface high concentration to the subsurface minima at the depth of chlorophyll a(Chl a) maxima and then increased again with depth at most of the stations. The average concentration of reactive Al in the upper 100 m water column was significantly lower in the cyclonic eddy((137±6) nmol/L) as compared with that in the noneddy waters((180±21) nmol/L). By contrast, the average concentrations of Chl a and silicate in the upper 100 m water column were higher in the cyclonic eddy and lower in the anticyclonic eddy. There was a significant negative correlation between the average concentrations of reactive Al and Chl a in the upper 100 m water column. The vertical distribution of reactive Al and the negative correlation between reactive Al and Chl a both suggest that the reactive Al in the upper water column was significantly influenced by biological removal processes. Our results indicate that mesoscale eddies could regulate the distribution of reactive Al by influencing the primary production and phytoplankton community structure in the western SCS.  相似文献   

5.
The East China Sea is a productive marginal sea with a wide continental shelf and plays an important role in absorbing atmospheric carbon dioxide and transferring terrigenous organic matter to the open ocean. To investigate the roles of heterotrophic bacteria in the biogeochemical dynamics in the East China Sea, bacterial biomasses(BB) and productions(BP) were measured in four cruises. The spatial distributions of the BB and the BP were highly season-dependent. Affected by the Changjiang River discharge, the BB and the BP were high in shelf waters(bottom depth not deeper than 50 m) and generally decreased offshore in August 2009. In December 2009 to January 2010, and November to December 2010, the BB and the BP were high in waters with medium bottom depth. The onshore-offshore decreasing trends of the BB and the BP also existed in May–June 2011, when the BB was significantly higher than in other cruises in shelf break waters(bottom depth deeper than 50 m but not deeper than 200 m). The results of generalized additive models(GAM) suggest that the BB increased with the temperature at a range of 8-20°C, increased with the chlorophyll concentration at a range of 0.02–3.00 mg/m3 and then declining, and decreased with the salinity from 28 to 35. The relationship between the temperature and the log-transformed bacterial specific growth rate(SGR) was linear. The estimated temperature coefficient(Q10) of the SGR was similar with that of the phytoplankton growth. The SGR also increased with the chlorophyll concentration. The ratio of the bacterial to phytoplankton production ranged from less than 0.01 to 0.40, being significantly higher in November–December 2010 than in May–June 2011. Calculated from the bacterial production and growth efficiency, the bacterial respiration consumed, on average, 59%, 72% and 23% of the primary production in August 2009, November–December 2010, and May–June 2011, respectively.  相似文献   

6.
The community composition,abundance and culturablity of heterotrophic bacterioplankton in the Dapeng Bay of the South China Sea were investigated by morphological method,bacterial cultivation and biochemical methods over an annual cycle.Aeromonas and Pseudomonas were the predominant genera among the Gram-negative bacteria.The bacterioplankton abundance fluctuated from 2.07×10 8 to 2.44×10 9 cells/dm 3 ,and culturable bacteria abundance ranged between 0.1×10 6 and 16.07×10 6 CFU/dm 3 .The Culturablity of heterotrophic bacteria ranged between 0.01% and 1.31%.The relationship between bacterial culturablity and the environmental factors was also studied in different sites of the Dapeng Bay.Throughout the bay,a significantly positive relationship was evidenced between bacterial culturability and temperature,meanswhile bacterial culturability was significantly inversely related with salinity.The positive relationship was shown at the central bay while a negative relationship was observed at the bay mouth and there was no significant correlation at top bay between bacterial culturablity and chlorophyll a of sea water.A positive relationship was found between culturability and DIN all the bay,but DIP showed a significantly negative relationship with bacterial culturability only at the mouth of the bay.  相似文献   

7.
北欧海比容高度及其与卫星高度计海表面高度异常的比较   总被引：2，自引：1，他引：1  
In this study the steric height anomaly which is calculated from the hydrological data(EN3) is compared with the sea level anomaly derived from satellite altimetry in the Nordic Seas. The overall pattern of steric height is that it is higher in the margin area and lower in the middle area. The extreme values of steric height linear change from1993 to 2010 occur in the Lofoten Basin and off the Norwegian coast, respectively. Such a distribution may be partly attributed to the freshening trend of the Nordic Seas. The correlation between SLA(sea level anomaly) and SHA(steric height anomaly) is not uniform over the Nordic Seas. The time series of SLA and SHA agree well in the Lofoten Basin and northern Norwegian Basin, and worse in the northern Norwegian Sea, implying that the baroclinic effect plays a dominant role in most areas in the Norwegian Sea and the barotropic effect plays a dominant role in the northern Norwegian Sea. The weaker correlations between SLA and SHA in the Greenland and Iceland Seas lead a conclusion that the barotropic contribution is significant in these areas. The area-mean SHA over the entire Nordic Seas has similar amplitudes compared with the SLA during 1996–2002, but SHA has become lower than SLA, being less than half of SLA since 2006.  相似文献   

8.
-Long-chain alkenones were detected in samples of sea surface sediments from the Chukchi Sea and the Bering Sea areas, the Arctic Pole. The analysis result indicates that C37:3 methylketone is pre dominate in the long-chain alkenones from the Chukchi and Bering Sea sediments. The abundance of C37to C39 unsaturated alkenones changes in an order of C37 ＞C38 ＞C39. Based on ∑37/∑38 ratio, the de tected organism precursors of the long-chain alkenones are mainly coccolithophrid (Emiliania huxleyi).By the calibration relationship between U3k7 and U37k indices, the sea surface paleotemperature in these seas is estimated. The estimated values of U37k vary from 4.147℃ to 5. 706℃, with a mean value of 5.092℃.  相似文献   

9.
The South China Sea(SCS) and the Arabian Sea(AS) are both located roughly in the north tropical zone with a range of similar latitude(0°–24°N). Monsoon winds play similar roles in the upper oceanic circulations of the both seas. But the distinct patterns of chlorophyll a(Chl a) concentration are observed between the SCS and the AS.The Chl a concentration in the SCS is generally lower than that in the AS in summer(June–August); the summer Chl a concentration in the AS shows stronger interannual variation, compared with that in the SCS; Moderate resolution imaging spectroradiometer(MODIS)-derived data present higher atmospheric aerosol deposition and stronger wind speed in the AS. And it has also been found that good correlations exist between the index of the dust precipitation indicated by aerosol optical thickness(AOT) and the Chl a concentration, or between wind and Chl a concentration. These imply that the wind and the dust precipitation bring more nutrients into the AS from the sky, the sub-layer or coast regions, inducing higher Chl a concentration. The results indicate that the wind velocity and the dust precipitation can play important roles in the Chl a concentration for the AS and the SCS in summer. However aerosol impact is weak on the biological productivity in the west SCS and wind-induced upwelling is the main source.  相似文献   

10.
The distribution of chlorophyll a(Chl a) and its relationships with physical and chemical parameters in different regions of the Bering Sea were discussed in July 2010. The results showed the seawater column Chl a concentrations were 13.41–553.89 mg/m2 and the average value was 118.15 mg/m2 in the study areas. The horizontal distribution of Chl a varied remarkably from basin to shelf in the Bering Sea. The regional order of Chl a concentrations from low to high was basin, slope, outer shelf, inner shelf, and middle shelf. The vertical distribution of Chl a was grouped mainly from single-peak type in basin, slope, outer shelf, and middle shelf, where the deep Chl a maxima(DCM) layer was observed at 25–50 m, 30–35 m, 36–44 m, and 37–47 m, respectively. The vertical distribution of Chl a mainly had three basic patterns: standard single-peak type, surface maximum type, and bottom maximum type in the inner shelf. The analysis also showed that the transportation of ocean currents may control the distribution of Chl a, and the effects were not simple in the basin of the Bering Sea. There was a positive correlation between Chl a and temperature, but no significant correlation between Chl a and nutrients. The Bering Sea slope was an area deeply influenced by slope current. Silicate was the factor that controlled the distribution of Chl a within parts of the water in the slope. Light intensity was an important environmental factor in controlling seawater column Chl a in the shelf, where Chl a was limited by nitrate rather than phosphate within the upper water. Meanwhile, there was a positive relationship between Chl a and salinity. Algal blooms broke out at Sta. B6 of the southwestern St. Lawrence Island and Stas F6 and F11 in the middle of the Bering Strait.  相似文献   

11.
高源  何剑锋  陈敏  林凌  张芳 《海洋学报》2015,37(8):96-104
2012年夏季中国第5次北极科学考察期间,对北冰洋楚科奇海及其北部边缘海浮游细菌丰度和生产力进行了测定,并将其与环境因子进行了相关性分析。结果显示,楚科奇海浮游细菌丰度的变化范围为0.56×108~6.41×108 cells/dm3,平均为2.25×108 cells/dm3;细菌生产力介于0.042~1.92mg/(m3·d)(以碳计)之间,平均为0.54mg/(m3·d)(以碳计),与已有研究结果基本相当。陆架区细菌丰度和生产力要明显高于北部边缘区,但前者的单位细菌生产力则较低。与环境因子的相关性分析显示,细菌丰度与温度和叶绿素a浓度存在显著正相关(p0.01),表明北极变暖导致的海水升温及浮游植物生物量的增加均会促进细菌的生长,从而进一步提高细菌在海洋生态系统和碳循环中的作用。但陆架区的细菌生产力与环境参数均没有显著相关性,表明其影响因素较为复杂;生产力在北部边缘区则仅与叶绿素a存在显著正相关(p0.01),表明浮游植物生长过程产生的溶解有机碳(DOC)是细菌生长最为主要的碳源,碳源的单一可能制约细菌的生产从而导致该海域无冰状态下细菌丰度的增加不如预期,但融冰过程带来的大量DOC将促进细菌活性的增加。  相似文献   

12.
通过2012年夏季第五次北极科学考察期间在楚科奇海及其邻近海域现场调查所获得的数据分析研究了海域的粒度分级叶绿素a浓度和初级生产力。结果表明,叶绿素a浓度和初级生产力的高值均出现在楚科奇海陆架区,并且远高于深海区。去程时调查海域水层平均叶绿素a浓度的变化范围为0.32~15.66mg/m3,平均(2.77±3.96)mg/m3,高值区出现在南部邻近白令海峡海域、北部阿拉斯加巴罗近岸和冰缘区;初级生产力的范围为50.11~943.28mg/(m2d),高值出现在冰缘水华区。返程时水层平均叶绿素a浓度的变化范围为0.07~1.52mg/m3,平均(0.41±0.40)mg/m3,高值仍出现在陆架区,但比去程时低了一个数量级;初级生产力的分布范围为12.31~41.35mg/(m2d),高值出现在陆架区。浮游植物粒度分级测定结果表明,在生物量较低的深海区,叶绿素a浓度和初级生产力的粒级结构以微微型浮游生物(Pico级份)占优势(其贡献率分别为46.1%和56.9%),小型(Net级份)和微型(Nano级份)对总叶绿素a浓度的贡献差异极小,分别为26.6%和27.3%,对总初级生产力的贡献分别为23.8%和19.3%;而在生物量较高的水深小于200m的陆架区,Net级份叶绿素a浓度所占百分比最高,Pico级份次之,Nano级份最低,分别为59.8%、27.9%和12.3%,初级生产力的粒级结构中叶绿素a浓度所占百分比由高到低同样是Net、Pico和Nano,所占百分比分别为60.6%,32.2%和7.2%。  相似文献   

13.
Standing stocks and production rates of phytoplankton and abundance of bacteria were investigated at 39 stations in the Seto Inland Sea, Japan during four crulses in October 1993, January, April and June 1994. Primary productivity was measured by the13C tracer method. Photosynthetic rate varied from 0.41 to 32.1 μgC/1/h with an average value of 4.67 μgC/l/h. Annual primary production was estimated to be 218 gC/m2/year. Annual primary production in this study was 1.8 times as high as the values which were previously reported at same area. The reason for the disagreement between our primary production value and previous values is not thought to be due to the difference of methods used for measuring primary production or the different Chl.a concentrations but to the method of estimating the primary production in the euphotic zone from thein vitro measurements. The distribution of bacterial cells in surface seawater was examined during the same cruises. Bacterial cell density ranged from 0.32 to 3.4×106 cells/ml. The density was relatively high in the eutrophic regions of Hiroshima Bay and Osaka Bay In addition, a high density of bacteria was also observed in an area within Suo Nada where Chl.a was relatively low. The disparity between Chla and bacterial density in Suo Nada suggests that bacterial abundance can be controlled by the availability of substrates other than phytoplankton exudate.  相似文献   

14.
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   

15.
The distribution of the total alkalinity (TA), the total inorganic carbon (TCO2), the calcium (Ca), and the CO2 partial pressure in the waters of the northwestern Bering Sea (Anadyr Bay) and in the western part of the Chukchi Sea is considered according to the data obtained in August–September 2002. It is shown that the areas treated were sinks of atmospheric CO2 in the summer of 2002: the total CO2 exchange between the atmosphere and the seawater was equal to about −20 mmol C/(m2 day). The net community production according to the TCO2 decrease in the upper photic layer in the west of the Chukchi Sea and in the Anadyr Bay waters amounted to 48 ± 12 and 72 ± 18 g C/(m2 year), respectively. The comparison with historical data allows one to tell about the pronounced increase of the TCO2, TA, and Ca concentrations in the waters of Anadyr Bay and in the western part of the Chukchi Sea in the summer 2002. The processes that might have caused the changes observed are the enrichment of the estuarine waters in marine salts under the ice formation in winter and the decrease of the supply of the waters of the Bering Slope Current to the northwestern part of the Bering Sea.  相似文献   

16.
The species composition, cell concentration (N), and biomass (B) of the phytoplankton, as well as the chlorophyll a (Chl a) concentration, primary production (PP), and the concentrations of the dissolved inorganic micronutrients (phosphorus, silica, nitrogen as nitrite), were estimated for Kandalaksha Bay (KB), Dvina Bay (DB), and the basin (Bas) of the White Sea in August of 2004. The micronutrient concentrations were lower compared to the average long-term values for the summer period. The Chl a concentration varies from 0.9 to 2.0 mg/m3 for most of the studied areas, reaching up to 7.5 mg/m3 in the Northern Dvina River estuary. The surface water layer of the DB was the most productive area, where the PP reached up to 270–375 mg C/(m3 day). The phytoplankton biomass varied from 11 to 205 mg C/m3 with the highest values observed in the Bas and DB. Three groups of stations were defined during the analysis of the phytoplankton’s species composition similarity. The dinoflagellates Dinophysis norvegica and Ceratium fusus were particular to the phytoplankton assemblages in the KB; the diatom Ditylum brightwellii was particular to the upper and central parts of the DB. These three phytoplankton species were less abundant in the Bas.  相似文献   

17.
We deployed a profiling buoy system incorporating a fast repetition rate fluorometer in the western subarctic Pacific and carried out time-series observations of phytoplankton productivity from 9 June to 15 July 2006. The chlorophyll a (Chl a) biomass integrated over the euphotic layer was as high as 45–50 mg Chl a m−2 in the middle of June and remained in the 30–40 mg Chl a m−2 range during the rest of observation period; day-to-day variation in Chl a biomass was relatively small. The daily net primary productivity integrated over the euphotic layer ranged from 144 to 919 mg C m−2 day−1 and varied greatly, depending more on insolation rather than Chl a biomass. In addition, we found that part of primary production was exported to a 150-m depth within 2 days, indicating that the variations in primary productivity quickly influenced the organic carbon flux from the upper ocean. Our results suggest that the short-term variability in primary productivity is one of the key factors controlling the carbon cycle in the surface ocean in the western subarctic Pacific.  相似文献   

18.
东亚边缘海区浮游植物春华的纬向与年际变化   总被引：1，自引：1，他引：0  
Combined studies of latitudinal and interannual variations of annual phytoplankton bloom peak in East Asian marginal seas(17°–58°N, including the northern South China Sea(SCS), Kuroshio waters, the Sea of Japan and the Okhotsk Sea) are rarely. Based on satellite-retrieved ten-year(2003–2012) median timing of the annual Chlorophyll a concentration(Chl a) climax, here we report that this annual spring bloom peak generally delays from the SCS in January to the Okhotsk Sea in June at a rate of(21.20±2.86) km/d(decadal median±SD). Spring bloom is dominant feature of the phytoplankton annual cycle over these regions, except for the SCS which features winter bloom. The fluctuation of the annual peak timing is mainly within ±48 d departured from the decadal median peak date, therefore this period(the decadal median peak date ±48 d) is defined as annual spring bloom period. As sea surface temperature rises, earlier spring bloom peak timing but decreasing averaged Chl a biomass in the spring bloom period due to insufficient light is evident in the Okhotsk Sea from 2003 to 2012. For the rest of three study domains, there are no significant interannual variance trend of the peak timing and the averaged Chl a biomass. Furthermore this change of spring phytoplankton bloom timing and magnitude in the Okhotsk Sea challenges previous prediction that ocean warming would enhance algal productivity at high latitudes.  相似文献   

19.
在北冰洋的高纬度海区，陆坡—海盆之间的交换对极北哲水蚤（Calanus hyperboreus）的种群补充具有非常重要的意义。为了研究极北哲水蚤在西北冰洋种群补充的地理差异，我们利用2003年夏季所采集的样品，分析了该物种的丰度、种群结构和体长分布。从总丰度的地理分布来看，极北哲水蚤主要分布在楚科奇海与楚科奇深海平原之间的陆坡区（CS-slope），而在水深较浅的楚科奇海并没有记录。在CS-slope区域，极北哲水蚤的总丰度在1 110.0—5 815.0个/m3之间，而其他海区的总丰度在40.0—950.0个/m3之间。从不同的发育期分布上来看，早期幼体（CI-CIV）在CS-slope区域占优势，而CV期幼体和成体在深水海盆区占优势。从体长的地理分布上来看，差异最为明显的是CⅢ期幼体，其在CS-slope区域的前体长在2.48—2.61 mm之间，而在其他海区的前体长在2.16—2.37 mm之间。与环境因子相关性的分析结果显示，早期幼体（CI-CIV）的丰度与叶绿素a的浓度呈正相关关系，而CV期幼体和成体却与叶绿素a的浓度呈负相关关系。我们的结果表明，极北哲水蚤可以通过加快第一个生长季节的发育速度而受益于初级生产力的增加，并且高生产力的CS-slope区域是陆坡-海盆之间种群补充的潜在来源。  相似文献   

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