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1.
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   

2.
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   

3.
A comprehensive analysis of sea ice and its snow cover during the summer in the Arctic Pacific sector was conducted using the observations recorded during the 7th Chinese National Arctic Research Expedition(CHIANRE-2016) and the satellite-derived parameters of the melt pond fraction(MPF) and snow grain size(SGS)from MODIS data. The results show that there were many low-concentration ice areas in the south of 78°N, while the ice concentration and thickness increased significantly with the latitude above the north of 78°N during CHIANRE-2016. The average MPF presented a trend of increasing in June and then decreasing in early September for 2016. The average snow depth on sea ice increased with latitude in the Arctic Pacific sector. We found a widely developed depth hoar layer in the snow stratigraphic profiles. The average SGS generally increased from June to early August and then decreased from August to September in 2016, and two valley values appeared during this period due to snowfall incidents.  相似文献   

4.
The West Pacific Ocean is considered as the provenance center of global marine life and has the highest species diversity of numerous marine taxa. The phytoplankton, as the primary producer at the base of the food chain,effects on climate change, fish resources as well as the entire ecosystem. However, there are few large-scale surveys covering several currents with different hydrographic characteristics. This study aimed to explore the relationships between the spatio-temporal variation in phytoplankton community structure and different water masses. A total of 630 water samples and 90 net samples of phytoplankton were collected at 45 stations in the Northwest Pacific Ocean(21.0°–42.0°N, 118.0°–156.0°E) during spring and summer 2017. A total of 281 phytoplankton taxa(5 μm) belonging to 61 genera were identified in the study area. The distribution pattern of the phytoplankton community differed significantly both spatially and temporally. The average abundances of phytoplankton in spring and summer were 797.07×10~2 cells/L and 84.94×10~2 cells/L, respectively. Whether in spring or summer, the maximum abundance always appeared in the northern transition region affected by the Oyashio Current, where nutrients were abundant and diatoms dominated the phytoplankton community;whereas the phytoplankton abundance was very low in the oligotrophic Kuroshio region, and the proportion of dinoflagellates in total abundance increased significantly. The horizontal distribution of phytoplankton abundance increased from low to high latitudes, which was consistent with the trend of nutrient distributions, but contrary to that of water temperature and salinity. In the northern area affected by the Oyashio Current, the phytoplankton abundance was mainly concentrated in the upper 30 m of water column, while the maximum abundance often occurred at depths of 50–75 m in the south-central area affected by the Kuroshio Current.Pearson correlation and redundancy analysis(RDA) showed that phytoplankton abundance was significant negatively correlated with temperature and salinity, but positively correlated with nutrient concentration. The phytoplankton community structure was mainly determined by nutrient availability, especially the N:P ratio.  相似文献   

5.
The distribution of phytoplankton and its correlation with environmental factors were studied monthly during August 2012 to July 2013 in the Yantian Bay. A total of 147 taxa of phytoplankton were identified, and the average abundance was in the range of 0.57×10~4 to 7.73×10~4 cell/L. A total of 19 species dominated the phytoplankton assemblages, and several species that are widely reported to be responsible for microalgae blooms were the absolutely dominant species, such as Skeletonema costatum, Navicula sp., Thalassionema nitzschioides,Pleurosigma sp., and Licmophora abbreviata. The monthly variabilities in phytoplankton abundance could be explained by water temperature, dissolved oxygen, salinity, dissolved inorganic nitrogen(DIN), and suspended solids. The results of a redundancy analysis showed that p H and nutrients, including DIN and silicate(SiO_4), were the most important environmental factors controlling phytoplankton assemblages in specific months. It was found that nutrients and pH levels that were mainly influenced by mariculture played a vital role in influencing the variation of phytoplankton assemblages in the Yantian Bay. Thus, a reduction of mariculture activities would be an effective way to control microalgae blooms in an enclosed and intensively eutrophic bay.  相似文献   

6.
Bacteria abundance, chlorophyll a, ATP and POC concentrations and respiration rates of microorganisms in the Changjiang Estuary and the plume were determined in July 1986. The high values of bacteria abundance occurred in the river mouth in association with suspended matter. It is assumed that bacteria were the major contributor to ATP and the main consumer of dissolved oxygen, and that the relationship between ATP and POC was present in that area. In the dilution zone (salinity; 25-30), instead of bacteria, phytoplankton was the major contributor to ATP and respiration rates, due to diatom bloom. Close relationships between Chi a and ATP, and ATP and POC were observed. Contribution of microbial carbon to POC was also estimated.  相似文献   

7.
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   

8.
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   

9.
夏秋季南黄海浮游植物群落及其调控因子   总被引:1,自引:1,他引:0  
The phytoplankton water samples were collected in two multidisciplinary investigations which were carried out during summer(June) and autumn(November to December) of 2011. Phytoplankton species composition and abundance data were accomplished by Uterm?hl method. The phytoplankton community was dominated by diatoms and dinoflagellates in the southern Yellow Sea(YS) in summer and autumn. In summer, Paralia sulcata and Prorocentrum dentatum were the predominated species, the cell abundance ranged from 0.074 to 107.733×103 cells/L with an average of 9.057×103 cells/L. Two phytoplankton high abundance appeared in northwest part of the survey area and the Changjiang River Estuary, respectively. In autumn, Par. sulcata became the predominant species, and the phytoplankton cell abundance ranged from 1.035×103 to 8.985×103 cells/L, the average was 3.263×103 cells/L. The phytoplankton abundance in surface layer presented the homogeneous distributions. Canonical Correspondence Analysis(CCA) method was applied for discovering the relationship between environmental factors and the common found phytoplankton species. The responses of phytoplankton to nutrients were varied between summer and autumn. The abundance of most predominant species, Par. sulcata was strongly correlated to temperature and salinity in autumn, but not the case in summer.  相似文献   

10.
The spatial variations of phytoplankton community structure in the Xiamen Western Bay during the summer and autumn cruises in 2001 were investigated based on HPLC analysis of photosynthetic pigments in algal cells and CHEMTAX processing of pigment data.The Chl a concentration reached 18.9 μg/L in the summer and declined to 0.28-2.17 in the autumn,respectively,consistent with the observation of diatom blooms in June.Among the accessory pigments,fucoxanthin was consistently the most abundant,ranging from 0.172 to 8.46 μg/L,with the maximum concentrations in June.19'-hexfucoxanthin and alloxanthin were the other two abundant pigments in the summer and autumn.In addition,19'-butanoyloxyfucoxanthin or peridinin was also important in late autumn.Generally the biomass of all the phytoplankton or each group was higher in the inner part than the mouth of this bay,represented by Chl a.CHEMTAX processing revealed the dominance of diatoms with their contribution of 14.6%-52.5% to the total Chl a,but its importance decreased in the autumn.Cryptophytes and Haptophytes,with an average contribution of 16.9%-31.4% and 12.1%-26.3%,were the other two important groups,especially in the autumn.On the contrary,Dinoflagellates and Chlorophytes were the minor groups,but the former became important sporadically in the autumn.It was suggested that there was distinctive variation in both the phytoplankton community structure and biomass between summer and autumn in the Xiamen Western Bay and the latter was coupled to the changes in temperature and dissolved oxygen.However,the spatial variation of the phytoplankton community structure was not as clear as the trend in the biomass of phytoplankton among all the sites in this bay.  相似文献   

11.
Nemopilema nomurai, an endemic and blooming jellyfish species in the waters of Korea, China and Japan, were monitored from June to October, 2017, in the Bohai and northwestern Yellow Seas, using the ship sighting method, as a preliminary study to investigate the spatiotemporal distribution of medusae. Monitoring revealed that the mass appearance of young medusae was observed in Liaodong Bay in summer. In late summer they disappeared and a high density zone shifted to the mid- and northern Bohai Strait. In early fall, healthy adults with relatively high density were observed in the area around the border of the South and North Yellow Seas. These results suggest that medusae of N. nomurai originated from the Bohai Sea and were advected into the Yellow Sea through the Bohai Strait.  相似文献   

12.
Nemopilema nomurai jellyfish, which are believed to complete their development in the East China Sea, have started migrating into the Yellow Sea in recent years. We obtained biomass estimates of this species in the Yellow Sea using bottom trawl fishing gear and sighting surveys over a 5-year period. These methods are effective for obtaining N. nomurai jellyfish density estimates and information about the community distribution near the bottom or surface of the sea. To verify the vertical distributions of giant jellyfish between, we used hydroacoustic equipment, including an optical stereo camera system attached to a towed sledge and an echo counting method with scientific echosounder system. Acoustic and optical data were collected while the vessel moved at 3 knots, from which the distribution and density of N. nomurai jellyfish were analyzed. Subsequently, the camera system was towed from a 7 m mean depth to sea level, with the detection range of the acoustic system extending from an 8 m depth to the bottom surface. The optical and acoustic methods indicated the presence of vertical distribution of 0.113 (inds/m3) and 0.064 (inds/m3), respectively. However, the vertical distribution indicated that around 93% of individuals occurred at a depth range of 10–40 m; thus, a 2.4-fold greater density was estimated by acoustic echo counting compared to the optical method.  相似文献   

13.
The food sources of aquacultured Apostichopus japonicus and the trophic levels of organisms in a sea cucumber(A. japonicus) and prawn(Penaeus japonica) polyculture system in a saltwater pond in Zhuanghe, Liaoning Province were examined using carbon and nitrogen stable isotopes. Across organisms, δ13C ranged from(–25.47±0.20)‰ to(–16.48±0.17)‰(mean±SD), and δ15N ranged from(4.23±0.49)‰ to(12.44±0.09)‰. The δ13C and δ15N contents of A. japonicus, P. japonica and Fenneropenaeus chinensis were comparatively higher than those of other organisms. Values of δ13C and δ15N revealed that P. japonica, Hemigrapsus sanguineus and Neomysis japonica comprised the largest component of the diet of A. japonicus. The mean trophic level of the organisms in this saltwater pond polyculture system was(2.75±0.08). P. japonica, A. japonicus, F. chinensis,Synechogobius hasta and Neomysis japonica were in the 3rd trophic level(2–3); jellyfish, H. sanguineus and zooplankton were in the 2nd trophic level(1–2); and Enteromorpha prolifera, benthic microalgae, periphyton and suspended matter primarily consisting of phytoplankton, bacteria and humus were in the primary trophic level(0–1).  相似文献   

14.
Based on the method developed for the delineation of E. huxleyi blooms, a new technique is achieved for (1) the automated detection of E. huxleyi blooms among coexisting massive blooms of microalgae species of other phytoplankton groups and (2) quantifying the boom surface of this type of coccolithophores. As a result, according to the data of the Climate Change Initiative Ocean Colour (OC CCI) for 1998–2013, we have obtained multiyear time series of variability in both the incidence of E. huxleyi bloom and its area in the North, Norwegian, Greenland, Barents, and Bering seas. It is found that E. huxleyi blooms propagate within the intra-annual cycle from the studied middle-latitude marine areas towards the northern areas of the Northern Atlantic Ocean (NAO) and the Arctic Ocean (AO) following the pathways of the main Gulfstream and its branches. It is also found that E. huxleyi blooms are formed annually, initially in the vicinity of the British Islands; then they successively emerge in the northward direction following the western coast of the Great Britain, turn over its northern extremity to reach, firstly, the North Sea (in May), the Norwegian Sea, and finally the Greenland Sea (in June). Then they burst out in the Barents Sea, where the typical period of blooming lasts until late August and, in some years, even to mid-September. We determine the patterns of maximal rates and duration of blooms for each of the seas studied in the Atlantic and Arctic Oceans. As for the Bering Sea, the temporal and spatial variability in the growth of E. huxleyi has an irregular pattern: after a period of remarkably high expression of this phenomenon in 1998–2001, there was an abrupt decrease in both the number and, especially, extent of bloom areas.  相似文献   

15.
A study on the reproductive cycle of the blood cockle Anadara granosa (Bivalvia: Arcidae) was conducted at three different areas in the northern region of the Strait of Malacca. A total of 1,920 samples of adult A. granosa (38–71 mm length) were collected from June 2009 until September 2010. Qualitative techniques (gonadal microscopic fresh smear test and histology analysis) as well as quantitative techniques (analysis of condition index and gonadal index) were used to predict monthly gonadal development stages of A. granosa. The gonadal index of A. granosa from Banda Aceh (Indonesia) (r = 0.469, P > 0.05) and Pulau Pinang (Malaysia) (r = 0.123, P > 0.05) did not show any correlation to their condition index, whereas the gonadal index of A. granosa from Lhokseumawe (Indonesia) (r = 0.609, P < 0.05) showed moderate positive correlation to the condition index. During the 16 month sampling period, four reproductive cycles were observed: each from three to six months. The process of releasing gametes is termed dribble spawning, and is the same in all populations. The principle component analysis (PCA) indicated that A. granosa reproduction was affected by interaction between internal physiological factors and indigenous environmental factors. In all sampling areas, phytoplankton density played a key role in the reproductive cycle in A. granosa. Information on the reproductive biology of this species is essential for species management and to improve the sustainability practices of the fisheries industry. These findings will provide basic information on the biology of the blood cockle A. granosa for stock management in the region.  相似文献   

16.
采集于泰国西南部安达曼近岸海域的一种立方水母Chiropsoides buitendijki,伞部呈典型的箱式、触手单侧分支,并缺乏幅间沟。触手带型呈1–3–2–3–2–3–2–3–1(1-主带,2-粗副带,3-细副带)。18S核糖体基因序列分析证实了其分类地位。同时,16S线粒体基因序列揭示样品内存在一定的遗传分化,说明该种内可能存在不同的群体,值得进一步研究。  相似文献   

17.
The distribution and feeding of dominant mesozooplankton species were studied in the estuary of the Ob River and adjacent inner Kara Sea shelf waters in September 2013. It was shown that the spatial distributions of Cyclops sp., Senecella siberica, Limnocalanus macrurus, Mysis oculata, Drepanopus bungei, Jashnovia tolli and Pseudocalanus sp. are related to the specific characteristics of the hydrographic regime in the estuarine frontal zone. The distributions of Cyclops sp., Senecella siberica, and Pseudocalanus sp. are mainly limited by salinity, while other species inhabit an area with a wide range of salinity values without clear preferences. Peaks of their abundance could be either consolidated or distanced in space. The populations of Jashnovia tolli, Drepanopus bungei, and Pseudocalanus sp. permanently inhabit the layer under the pycnohalocline; the populations of Cyclops sp. and Mysis oculata inhabit the upper mixed layer. Limnocalanus macrurus demonstrates a different vertical distribution pattern: the copepod undertakes diel vertical migrations in the southern part of the estuarine frontal zone; in its northern part, the population is concentrated below the pycnocline during day and night. The differences in the distributions of the studied species determine their feeding behavior and their role in phytoplankton grazing. The most intense utilization of biomass and production of autotrophic phytoplankton by zooplankton occur in the freshened water zone and the adjacent southern periphery of the estuarine frontal zone: the total daily phytoplankton consumption makes up 10–18% of the biomass and 60–380% of primary production. Daily zooplankton consumption of phytoplankton in the estuarine frontal zone decreases to 2–7% of the biomass and to 14% of primary production; in inner shelf waters, the values do not exceed 1% for both phytoplankton biomass and production.  相似文献   

18.
Based on the archived data of the ocean color scanner MODIS-Aqua for 2003–2011, we constructed the long-term monthly mean distributions of the reflectance Rrs of the Black Sea for April, May, June, and September in order to visualize the contributions of seasonal factors to the long-term variability of the basin’s images. In April, the Rim Current’s branch west of 34° E is visualized by higher Rrs in different regions of the visible spectrum due to the transport of suspended matter caused by intensification of the Rim Current during the winter-spring period. During the June coccolithophore “blooms,” the long-term Rrs level is 2–3 times higher when compared to the previous and subsequent months. This excess is particularly considerable outside the shelf and coastal areas. The open sea Rrs distribution in June features horizontal inhomogeneity. The seasonal trend of the Rrs spectra on the Black Sea NW shelf is explicitly related to the annual cycle of the continental runoff effects.  相似文献   

19.
In the East China Sea(ECS), the succession of causative species responsible for blooms is a recurrent phenomenon during the spring, which changes from diatoms to dinoflagellates. Observations from space and in situ cruises captured this pattern of succession during spring of 2005. In this study, we coupled two biological models, which were developed previously for Skeletonema costatum and Prorocentrum donghaiense,into a circulation model tailored for the ECS. The coupled biophysical model was used to hindcast the blooms and to test the hypothesis proposed in earlier studies that phosphate(PO4 3–) is the first-order decider of the succession. The coupled model successfully reproduced the hydrodynamics(as described in a companion paper by Sun et al.(1), the spatiotemporal distribution of the chlorophyll a(Chl a) concentration, and the species succession reasonably well. By analyzing the effects of different factors on the surface Chl a distribution, we confirmed that the offshore boundaries of the blooms were confined by PO4 3–. In addition, we suggest that surface wind fields may modulate the horizontal distribution of blooms. Thus, during the dispersal of blooms, surface winds coupled with PO4 3– may control the succession of blooms in the ECS. The proposed coupled model provides a benchmark to facilitate future improvements by including more size classes for organisms, multiple nutrient schemes, and additional processes.  相似文献   

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