Distribution of general aerobic heterotrophic bacteria in sediment core taken from the Canadian basin and the Chukchi Sea

The occurrence percentage and abundance of General Aerobic Hetero- trophic Bacteria （GAB） were determined by using the method of MPN for 182 sub- samples from 10 sediment cores taken from the Canadian basin and the Chukchi Sea at two different culturing temperatures. The results showed that the general occurrence percentage of GAB was quite high, average abundanees of GAB at cultured temperatares of 4℃ and 25℃ were 4.46 ×10^7 and 5.47×10^7 cells·g^-1（wt）, respectively. The highest abundance of GAB occurred at 20 -22 cm section in the sediment. GAB abundances changed among the section of sediments, but there is a trend ： the a-bundances at the middle or lower sections were lower than those at upper section. Cultivation at 25℃ could improve the occurrence percentage and abundances of GAB, which suggests that the increasing of temperature may change the living circum-stances of GAB. The differences of GAB among the latitudes areas indicated that occurrence percentage and abundances of GAB in middle latitude areas were higher than those in the higher or lower latitude areas, and were more obvious at 4℃ than those at 25℃. The GAB abundances in sediment under the shallower water seemed to be low- er than those in sediments under the deeper water and this status was more obvious at 25℃ than that at 4℃.     

Abundance of general aerobic heterotrophic bacteria in the Bering Sea and Chukchi Sea and their adaptation to temperature

1　IntroductionInthedeepseawithawatertemperaturelowerthan5℃andtheseabottom ,theor ganicmattersareoxidizedmainlybytheaerobicbacteria (BenderandHeggie 1 984;Her bert 1 986) ,whichmeansthattheaerobicbacteriainthisenvironmentareratherabun dant.Thearcticseaareaisanareawhereenvironmentispermanentlycold ,butsomere searchresults (Sahmetal.1 998)indicatethattherearedominantbacteria eubacteriainthearcticseawaterandsediment,andtheiradaptationtotemperaturehasnosubstantialdifferenceincomparisonwiththatof…     

Grazing of Salpa thompsoni on phytoplankton in summer in the Prydz Bay region, Antarctica

During the CHINARE-Ⅺ cruise in austral summer of 1998/1999, the abundance and feeding activity of Salps thompsoni were investigated in the Prydz Bav region. Salps samples were collected by vertical tows from the depth of 200 m to the surface with a conical net of 330 μm mesh-size. At Ⅵ-3 station, the grazing rates were studied by the gut fluorescence method and culture experiments. S. Thompsoni was mainly distributed in the northern part of the survey area, and its maximum densities reached to 2795 ind. · 1000 m-3. A dramatic decrease in salp stock was observed at the Marginal Ice Zone. The results of the feeding experiments at the Ⅵ-3 show that the gut pigment contents of S. thompsoni ranged from (0. 14 - 1.27) μig ind. -1(average 0. 98 μg ind.-1). The individual ingestion rate is 7. 9 μg ind. -1 · day-1, and the filtration rate is 28 L ind. -1 · day-1 Through the daily grazing rate of S. thompsoni, which takes account of less than 1% of the phytoplankton standing stock, it shows arelatively higher grazing impress on the primary production (72. 2 % ).     

Study on the distribution,abundance and growth condition of Antarctic Krill(Euphausia superba)in the Prydz Bay region,Antarctica during the Austral summer of 1999/2000

Antarctic krill (Euphausia superba) were collected from the Prydz Bay region during the austral summer of 1999/2000. The sample - collection was made at 15 sites in 3 longitudinal transects. Although krill were encountered at 14 sites, the abundance was comparatively low in general. The main component of the krill population was of post -larval stages. The mean numerical and weight density of krill integrated for all sampling stations in the survey area were 16. 17 ind. 1000 m -3and 12.02 g 1000 m -3 , respectively. In the survey area, stations with larger krill density are mainly located in the slope zone, except that the largest sample was collected in the open sea zone. No krill occurred in the only station of the shelf zone during our investigation. Krill collected from the slope zone were under better growth condition than those from the open sea zone, but when the survey area is considered as a whole, the growth condition is normal. The results of the comprehensive analysis of the environmental fa     

Composition and distribution of planktonic ciliates in the southern South China Sea during late summer: Comparison between surface and 75 m deep layer

Ciliates are very important components in most marine ecosystem.They are trophic link between the microbial food web and grazing food chain.In this study,ciliates were collected from 11 sites in the southern South China Sea(SCS) during August 25 to September 28,2011.Their composition and distribution at the surface and 75 m deep depth of the ocean were studied.A total of 30 species belonging to 22 genera were identified,and 22 species of 15 genera were Tintinnids.Eutintinnus fraknoii and E.stramentus were the most common species.The other dominants were strombidiids ciliates including Strombidium conicum and S.globosaneum,which were followed by the tide form,Mesodinium pulex.Ciliates abundance ranged from 46 ind L~(-1) to 368 ind L~(-1) in the open sites,46–368 ind L~(-1) at surface and 73–198 ind L~(-1) at 75 m deep layer.In the Yongshu reef,ciliates abundance ranged from 167 ind L~(-1) to 365 ind L~(-1) in the water column,similar to that in Sanya coral reef waters.Ciliates composition showed obvious difference between surface and 75 m deep layer at station S2(P 0.05),while no similar result was observed at other sites.At 75 m deep layer,salinity was negatively related to mixed layer depth(P 0.05),but positively to chlorophyll a concentration(P 0.05),indicating that the change of vertical mixing in water column influenced vertical distribution of ciliates in the southern SCS.     

The relationship between cyanobacteria and environmental factors in the Bering Sea

During the first Chinese Scientific Expedition to the Arctic in July - September 1999, cyanobacteria in the Bering Sea were measured by epifluorescence microscopy. Cyanobacterial abundance varied from 0 to 7. 93 × 103 cell/ml and decreased along a northerly directed latitudinal gradient in horizontal distribution. Cyanobacteria did not occur at station Bl - 12 (north of 60 °N). Vertically, high cya-nobacterial abundance appeared in the upper 25 - 50 m and decreased rapidly below 50 m. There were no cyanobacteria at the 150 m. Seawater temperature and NH4+ -N are suggested to affect the distribution of cyanobacteria.     

Annual variation in Calanus sinicus abundance and population structure in the northern boundary area of the Yellow Sea Cold Water Mass

The Yellow Sea Cold Water Mass （YSCWM） was suggested as an over-summering site of the dominant copepod species Calanus sinicus in coastal Chinese seas. Population abundance and structure were investigated by monthly sampling along three transects across the northern boundary of the YSCWM during 2009-2010. Results show that thermal stratification existed from June to October and that the vertical thermal difference increased with depth. Generally, total abundance was lowest in October and highest in June, and the female/male sex ratio was highest in February and lowest in August. Evident spatial differences in abundance were observed during the existence of the YSCWM. In June, total abundance averaged 158.8 ind/m~ at well-stratified stations, and 532.1 ind/m3 at other stations. Similarly, high abundances of 322.0 and 324.4 ind/m3 were recorded from July to August inside the YSCWM, while the abundance decreased from 50.4 to 1.9 ind/m3 outside the water mass. C. sinicus distribution tended to even out over the study area in September when the YSCWM disappeared. We believe that the YSCWM may retard population recruitment in spring and preserve abundant cohorts in summer. The summer population was transported to neritic waters in autumn. In addition to low temperatures, stable vertical structure was also an essential condition for preservation of the summer population. C. sinicus can survive the summer in marginal areas in high abundance, but the population structure is completely different in terms of C5 proportion and sex ratio.     

Community composition,abundance and biomass of zooplankton in Zhangzi Island waters,Northern Yellow Sea

Samples were collected monthly from the sea area around Zhangzi Island,northern Yellow Sea,from July 2009 to June 2010.Vertical net towing was used to examine spatial and temporal variability in zooplankton abundance and biomass.Overall,C alanus sinicus and Saggita crassa were the dominant species found during the study period,while the amphipod T hemisto gracilipes was dominant in winter and spring.Vast numbers of the ctenophore species of the genus Beroe were found in October and November.It was not possible to count them,but they constituted a large portion of the total zooplankton biomass.Zooplankton species diversity was highest in October,and species evenness was highest in April.Zooplankton abundance(non-jellyfi sh)and biomass were highest in June and lowest in August,with annual averages of 131.3 ind./m3and 217.5 mg/m3,respectively.Water temperature may be responsible for the variations in zooplankton abundance and biomass.B eroe biomass was negatively correlated with other zooplankton abundance.Longterm investigations will be carried out to learn more about the infl uence of the environment on zooplankton assemblages.     

Meiofauna Distribution in Intertidal Sandy Beaches Along China Shoreline(18?–40?N)

In this study,the distribution pattern of meiofauna from nine sandy beaches at six latitudinal gradients along Chinese coast between 18 and 40?N was studied on their meiofauna abundance to examine the effect of latitudinal gradients.In general,meiofauna abundance was lower in four subtropical beaches in Xiamen(24?N) and Zhoushan(29?N) than that in other beaches.Meiofauna abundance differed little between tropical and temperate beaches.The taxonomic structure of meiofauna showed a dominance of nematode in colder area.The relative composition of turbellarians and polychaetes increased in warmer area.In addition to latitudinal gradient,salinity,oxygenation,sediment grain size affect also the meiofauna latitudinal distribution.As for horizontal distribution,the highest meiofauna abundance was found in low tidal zone at tropical beaches,and in middle tidal zone at temperate beaches.The horizontal distribution of meiofauna was controlled by both physical and biotic factors including feeding and anthropogenic activities.Although meiofauna abundance exhibited a horizontal difference,the composition of meiofaunal main taxa was unanimous horizontally at all beaches at the same sampling latitude.     

Variation of alkaline phosphatase activity in sediments of shrimp culture ponds and its relationship with the contents of C,N and P

1Introduction Activities of extracellular enzymes can serve as theindicators of organic matter content.Enzyme assayinghas been used in the analyses of dissolved organic ma-terials in aquatic environments(Chrost,1991),massloss of plant litter in terrestrial systems(Sinsabaughet al.,1992;Sinsabaugh et al.,1994),processing ofpaniculate and dissolved organic carbon(POC,DOC)in streams(Sinsabaugh and Findlay,1995;Findlayet al.,1998),and processing of particulate organicmatter(POM)in wetlands(J…     

Effects of Pseudoalteromonas sp. BC228 on digestive enzyme activity and immune response of juvenile sea cucumber (Apostichopus japonicus)

A marine bacterium, Pseudoalteromonas sp. BC228 was supplemented to feed in a feeding experiment aiming to determine its ability of enhancing the digestive enzyme activity and immune response of juvenile Apostichopus japonicus. Sea cucumber individuals were fed with the diets containing 0(control), 105, 107 and 109 CFU g-1 diet of BC228 for 45 days. Results showed that intestinal trypsin and lipase activities were significantly enhanced by 107 and 109 CFU g-1 diet of BC228 in comparison with control(P 0.01). The phagocytic activity in the coelomocytes of sea cucumber fed the diet supplemented with 107 CFU g-1 diet of BC228 was significantly higher than that of those fed control diet(P 0.05). In addition, 105 and 107 CFU g-1 diet of BC228 significantly enhanced lysozyme and phenoloxidase activities in the coelomic fluid of sea cucumber, respectively, in comparison with other diets(P 0.01). Sea cucumbers, 10 each diet, were challenged with Vibrio splendidus NB13 after 45 days of feeding. It was found that the cumulative incidence and mortality of sea cucumber fed with BC228 containing diets were lower than those of animals fed control diet. Our findings evidenced that BC228 supplemented in diets improved the digestive enzyme activity of juvenile sea cucumber, stimulated its immune response and enhanced its resistance to the infection of V. splendidus.     

Macrobenthic community structure and species composition in the Yellow Sea and East China Sea in jellyfish bloom

To understand the characteristics of macrobenthic structures and the relationship between environment and benthic assemblages in jellyfish bloom, we studied the macrobenthos and related environmental factors in the coastal waters of the Yellow Sea and East China Sea. Data were collected during two seasonal cruises in April and August of 2011, and analyzed with multivariate statistical methods. Up to 306 macrobenthic species were registered from the research areas, including 115 species of Polychaeta, 78 of Crustacea, 61 of Mollusca, 30 of Echinodermata, and 22 of other groups. Nine polychaete species occurred at frequencies higher than 25% from the sampling stations： Lumbrineris longifolia, Notomastus latericeus, Nin6e palmata, Ophelina acuminata, Nephtys oligobranchia, Onuphis geophiliformis, Glycera chirori, Terebellides stroemii, and Aricidea fragilis. Both the average biomass and abundance of macrobenthos are higher in August （23.8 g/m^2 and 237.7 ind./m^2） than those in April （11.3 g/m^2 and 128 ind./m^2）; the dissimilarity ofmacrobenthic structures among stations is as high as 70%. In terms of the dissimilarity values, we divided the stations into four clusters in spring and eight in summer. The ABC curve shows that the macrofauna communities in high jellyfish abundance were not changed. Canonical correspondence analysis showed that depth, temperature, median grain size, total organic carbon of sediment and total nitrogen in sediment were important factors affecting the macrozoobenthic community in the study area.     

Comparative study of hydrographic conditions for algal bloom formation in the coastal waters of east and west of Hong Kong during 1998

Phytoplankton abundance was found to be positively correlated with seasonal changes of seawater temperature in Port Shelter and Lamma Channel, Hong Kong in 1998. Rising water temperature from around 20°C to 25°C coincided with an increase in phytoplankton abundance at both locations. Heavy rains from June to September reduced salinity from 30 to 20, but the decrease in salinity was not correlated with a decline in phytoplankton abundance. In spring 1998, over 0.6×106 cells dm-3 and 0.1×106 cells dm-3 of the...     

Ecology of macrozoobenthic communities in two plateau lakes of Southwest China

Ecological studies on macrozoobenthos were conducted in two small plateau lakes in the Yunnan-Guizhou Plateau, Southwest China： Xingyun Lake （XL）, a eutrophic lake whose main source of primary production was phytoplankton （Chl α=99.76±24.01 μg/L）, and Yangzong Lake （YL）, a mesotrophic lake. Sampling was carried out from October 2002 to May 2004. Altogether 23 benthic taxa were identified in XL and 21 taxa in YL. The density of benthos in XL was much lower than that in YL, but the biomass was about equal in the two lakes, being I 423 ind/m^2 and 8.71 g/m^2 in XL and 4 249 ind/m^2 and 8.60 g/m^2 in YL. The dominant species were Limnodrilus hoffmeisteri, Branchiura sowerbyi, Aulodrilus pluriseta and Chironomus sp. in XL and Limnodrilus hoffrneisteri, Aulodrilus pluriseta and Bellamya sp. in YL. Seasonal fluctuation occurred, showing richer species in summer and winter, but the density and biomass varied in different ways in the two lakes. Analyses on functional feeding groups indicate that collector-gatherers were predominant, but the relative abundances of other groups were different. Stepwise multiple regression analysis demonstrated that the water depth, conductivity and chlorophyll a were the key factors affecting macrozoobenthic abundance in the lakes.     

Spatial and temporal variations of Synechococcus and picoeukaryotes in the Taiwan Strait,China

The size-fractionated phytoplankton biomass, and the spatial and temporal variations in abundance of Synechococcus (SYN) and picoeukaryotes (PEUK) were measured in the Taiwan Strait during three cruises (August 1997, February-March 1998, and August 1998). The results show that picophytoplankton and nanophytoplankton dominate the phytoplankton biomass, in average of 38% and 40%, respectively. SYN and PEUK varied over time in abundance and carbon biomass, greater in summer than in winter, in range of (7.70–20...     

Determination of ice thickness, subice topography and ice vol-ume at Glacier No. 1 in Tien Shan, China by ground penetrating radar

We describe a radio-echo sounding (RES) survey for the determination of ice thickness, subglacial topography and ice volume of Glacier No. 1 , in Tien Shan, China, using ground-penetrating radar (GPR). Radar data were collected with 100-MHz antennas that were spaced at 4 m with a step size of 8 m. The images produced from radar survey clearly show the continuity of bedrock echoes and the undulation features of the bedrock surface. Radar results show that the maximum ice thickness of Glacier No. 1 is 133 m, the thickness of the east branch of Glacier No. 1 averages at 58. 77 m while that of the west branch of Glacier No. 1 averages at 44. 84 m. Calculation on ice volume indicates that the ice volume of the east branch of Glacier No. 1 is 51. 87 × 106 m3 and that of the west branch of Glacier No. 1 is 20. 21 × 106 m3. The amplitude of the undulation of the bedrock surface topography revealed by radar profiles is larger than that of the glacier surface topography, indicating that the surface relief does     

Some geochemical patterns of shelf sediments of the China Seas

Geochemical patterns of shelf sediments of China Seas are discussed in the following order: 1) the grain-size control of elements, 2) zonal distribution of elements along the coast, 3) estuarine enrichment of elements, 4) correlation of elements, 5) philo-detrital property of elements, 6) philo-continental property of elements, 7) rapid accumulation rate of elements. Statistics show that the abundance of indicator elements in shelf sediments is relatively close to that in terrestrial rocks and continental crust, and the abundance distribution pattern of elements in shelf sediments is similar to that in continental crust.     

Radiolaria fossils in the surface sediments and sedimentary environment in the Bering Sea

Totally 2472 grains of Radiolaria belonging to 36 Genera and 45 species are distinguished from 12 surface sediments in the Bering Sea. The distribution characteristics of Radiolaria fossils in the surface sediments are as follows: (1) From the shelf of shallow water to the upper of continental slope, there are a few Radiolaria fossils and monotonous genus and species; (2) In the lower of continental slope, Radiolaria fossils are poor in the volcanic cinders and turbidite; (3) The abundance and diversity of Radiolaria fossils are high in clay of the basin. The dominant species of Radiolaria is Spongotrochus glacialis on the continental shelf. Current, topography, water depth, and temperature etc. are key factors influencing Radiolaria distribution. The sources of sediments mainly are terrigenous, biogenic and volcanic sediments in the survey area and they are mostly from the Kamchatka peninsula in the east of Russia and the Aleutian Islands.     

Life history, secondary production and trophic basis of two dominant mayflies in a subtropical stream of China

Mayflies constitute a major part of macroinvertebrate biomass and production in Iotic ecosystems, and play an important role in material cycle and energy flow. There are more than 250 species of mayflies in rivers and streams of China. In order to learn their ecological functions, an investigation on life cycle, production and trophic basis of dominant species of mayflies in a second-order branch of Hanjiang River basin, Hubei, China was carried out during June 2003 to June 2004. The results showed that the dominant mayfly species Epeorus sp. and Caenis sp. developed two generations per year; in term of Epeorus sp., pupation mainly occurred in spring and then from late summer to early autumn, while Caenis sp. pupated in spring and autumn. The abundance and biomass of the Epeorus sp. population peaked twice （1 226 ind/m^2, 3.142 5g/m^2） in April and June. Caenis sp. also had two peaks （307ind/m^2, 1.590 g/m^2）, but in February and June. Cohort production and cohort P/B ratio of Epeorus sp. were 161.009 g/m2 wet weight and 7.7, respectively, and annual production and P/B ratio were 267.46g/m^2.a wet weight and 15.4, respectively; cohort production and P/B ratio of Caenis sp. were 26.7995g/m^2 wet weight and 4.7, its annual production and P/B ratio were 53.60 g/m2.a wet weight and 9.4, respectively. For Epeorus sp., the proportions contributing to secondary production of the main food types were： amorphous detritus, 33.46%; fungi, 10.83%; vascular plant detritus, 1.80%; diatoms, 53.90%; for Caenis sp., the proportions were 70.79%, 6.90%, 3.52% and 18.77%, respectively.