In-situ studies of microzooplankton grazing pressure on phytoplankton in Jiaozhou Bay, China

Preliminary studies on microzooplankton grazing were conducted with dilution method in Jiaozhou Bay from summer 1998 to spring 1999. Four experiments were carried out at St. 5 located at the center of Jiaozhou Bay. Chlorophyll a concentrations were consistently dominated by netphytoplankton (net-, >20μm), except during the autumn 1998 cruise, when they were dominated by nanophytoplankton(nano-, 2–20μm). The contribution of picophytoplankton (pico-, <2μm) to total chlorophyll a concentrations (<200μm) varied considerably between cruises. Instantaneous growth coefficients(u) of phytoplankton varied from 0.098 to 1.947d⁻¹, with mean value of 0.902d⁻¹. Instantaneous coefficients(g) of microzooplankton grazing on phytoplankton ranged from 0.066 to 0.567d⁻¹, mean value of 0.265d⁻¹, which was equivalent to daily lose of 21.9% of the initial standing stock and 58.1% of the daily potential production. Project No KZCX3-SW-214 supported by Chinese Academy of Sciences.     

Bioaccumulation of Pb<Superscript>2+</Superscript> and its effects on growth,morphology and pigment contents of <Emphasis Type="Italic">Spirulina</Emphasis> (<Emphasis Type="Italic">Arthrospira</Emphasis>) <Emphasis Type="Italic">platensis</Emphasis>

A laboratory experiment was conducted to assess the bioaccumulation of Pb²⁺ and its effects on growth, morphology and pigment contents of Spirulina (Arthrospira) platensis. The specimen cultured in Zarrouk liquid medium was treated with various initial metal concentrations (0, 5, 10, 30, 50 and 100 μg mL⁻¹). The growth of S. platensis was adversely affected by Pb²⁺ at high concentrations (30, 50 and 100 μg mL⁻¹). However, at low concentrations (5 μg mL⁻¹), Pb²⁺ could stimulate its growth slightly. The pigment contents (chlorophyll α and β carotene) were decreased in a dose-dependent manner. The highest reductions (67% and 53% respectively in chlorophyll α and β carotene) were observed in 100 μg mL⁻¹ treatment group. The LC₅₀ (96 h) of Pb²⁺ was measured as 75.34 μg mL⁻¹. Apart from a few cases of filament breakages at elevated concentrations (50 and 100 μg mL⁻¹), morphological abnormalities are not specific. Metal bioaccumulation increased with Pb²⁺ concentrations, but decreased with exposure time. The maximum accumulated amount was 188 mg g⁻¹ dry weight. The bioconcentration factor (BCF) reached to a peak at day 2, followed by a gradual reduction for all the exposure concentrations. S. platensis is able to tolerate considerably high Pb²⁺ concentrations. Consequently it can be used as a potential species to remove heavy metal from contaminated waters.     

Annual production ofBranchiura sowerbyi (Oligochaeta: Tubificidae) in the Donghu Lake,Wuhan, China

Branchiura sowerbyi in the Donghu Lake (Wuhan, China) completes its life cycle in one year. Its production rates were 6.7 g m⁻² yr⁻¹ (wet weight) during the period from April 1962 to May 1963 and 8.6g m⁻² yr⁻¹ during the period from August 1963 to August 1964. The standing stocks in corresponding periods were 1.9g m⁻² (wet weight) and 1.1g m⁻², and theP/B ratios were 3.6 and 7.8. Based on the standing stock during 1973–1975, an evaluation of recent productin levels ofB. sowerbyi in Donghu Lake has also been made (i.e. 5.7–33.5g m⁻² yr⁻¹).     

CHANGE IN THE ACTIVITY OF THE RESPIRATORY ELECTRON TRANSPORT SYSTEM IN NATURAL PHYTOPLANKTON ASSEMBLAGES AND CULTURED ALGAE

Activities of the respiratory electron transport system (ETS), C uptake, chlorophyll and temperature were determined at a station in the center of Donghu Lake. Seasonal, fluctuations in ETS-activities ranged from 100 to 460μg O2 h-1.L-1. Production: respiration ratio (P/R) calculated from C uptake and ETS-activity, ranged from 0.2 to 6.8. The test on cultured algae ETS-activity revealed marked differences in different growth phases. ETS activity is suggested as an indicator of lake nutrient status.     

Silicon limitation on primary production and its destiny in Jiaozhou Bay, China VIII: The variation of atmospheric carbon caused by both phytoplankton and human

Statistical analysis on data collected in the Jiaozhou Bay (Shandong, China) from May 1991 to February 1994 and those collected in Hawaii from March 1958 to December 2007 shows dynamic and cyclic changes in atmospheric carbon in the Northern Pacific Ocean (NPO), as well as the variation in space-time distribution of phytoplankton primary production and atmospheric carbon in the study regions. The study indicates that the human beings have imposed an important impact on the changing trends of the atmospheric carbon. Primary production in the Jiaozhou Bay presents a good example in this regard. In this paper, dynamic models of the atmospheric carbon in the NPO, the cyclic variations in the atmospheric carbon, and primary production in the Jiaozhou Bay are studied with simulation curves presented. A set of equations were established that able to calculate the rate and acceleration of increasing carbon discharged anthropologically into the atmosphere and the conversion rate of phytoplankton to atmospheric carbon. Our calculation shows that the amount of atmospheric carbon absorbed by one unit of primary production in the Jiaozhou Bay is (3.21−9.74)×10⁻⁹/(mgC·m⁻²d⁻¹), and the amount of primary production consumed by a unit of atmospheric carbon is 102.66–311.52 (mgC·m⁻²d⁻¹/10⁻⁶). Therefore, we consider that the variation of atmospheric carbon is a dynamic process controlled by the increase of carbon compound and its cyclic variation, and those from anthropologic discharge, and phytoplankton growth.     

Size-fractionated phytoplankton biomass in autumn of the Changjiang （Yangtze） River Estuary and its adjacent waters after the Three Gorges Dam construction

A cruise was undertaken from 3rd to 8th November 2004 in Changjiang （Yangtze） River Estuary and its adjacent waters to investigate the spatial biomass distribution and size composition of phytoplankton. Chlorophyll-a （Chl-a） concentration ranged 0.42-1.17 μg L^-1 and 0.41-10.43 μg L^-1 inside and outside the river mouth, with the mean value 0.73 μg L^-1 and 1.86 μg L^-1, respectively. Compared with the Chl-a concentration in summer of 2004, the mean value was much lower inside, and a little higher outside the river mouth. The maximal Chl-a was 10.43 μg L^-1 at station 18 （122.67°E, 31.25°N）, and the region of high Chl-a concentration was observed in the central survey area between 122.5°E and 123.0°E. In the stations located east of 122.5°E, Chl-a concentration was generally high in the upper layers above 5 m due to water stratification. In the survey area, the average Chl-a in sizes of 〉20 μm and 〈20 μm was 0.28 μg L^-1 and 1.40 μg L^-1, respectively. High Chl-a concentration of 〈20 μm size-fraction indicated that the nanophytoplankton and picophytoplankton contributed the most to the biomass of phytoplankton. Skeletonema costatum, Prorocentrum micans and Scrippsiella trochoidea were the dominant species in surface water. The spatial distribution of cell abundance of phytoplankton was patchy and did not agree well with that of Chl-a, as the cell abundance could not distinguish the differences in shape and size of phytoplankton cells. Nitrate and silicate behaved conservatively, but the former could probably be the limitation factor to algal biomass at offshore stations. The distribution of phosphate scattered considerably, and its relation to the phytoplankton biomass was complicated.     

Alkaline protease production by a strain of marine yeasts

Yeast strain 10 with high yield of protease was isolated from sediments of saltern near Qingdao, China. The protease had the highest activity at pH 9.0 and 45℃. The optimal medium for the maximum alkaline protease production of strain 10 was 2.5 g soluble starch and 2.0 g NaNO3 in 100 mL seawater with initial pH6.0. The optimal cultivation conditions for the maximum protease production were temperature 24.5 ℃, aeration rate 8.0 L min^- 1 and agitation speed 150 r min^-1 . Under the optimal conditions, 623.1 Umg^-1 protein of alkaline protease was reached in the culture within 30 h of fermentation.     

Early development of Costaria costata (C. Agardh) Saunders and cultivation trials

Costaria costata (C. Agardh) Saunders is one of common kelps distributed in many coastal areas worldwide; however, in China, no reports have been made on cultivation of the genus. To investigate potential cultivation of the species in the northern part of China, trials on isolation and preservation of the gametophytes were conducted using C. costata from Korea; growth and development of the gametophytes were observed. We showed that at 10±1°C, 60 μmol m⁻²s⁻¹ and 12:12 h (L:D), freshly released zoospores settled down within 1 hour, and then developed into the primary cell during the following 2 days. After a vegetative growth phase lasting 6–8 days, female gametophytes became 3–4 times larger in diameter than that of the primary cell, but still remained at a unicellular stage, while male gametophytes divided into 4–10 cells with only a slight change in size. Fertilization occurred within 10 days after the zoospores were released from the sporangia, and the apical and basal tissues of the juvenile sporophyte divided and differentiated into the blade and stipe. Temperature and irradiance influenced gametophytic vegetative growth and developmental patterns. Generally, low irradiance (15 μmol m⁻²s⁻¹ and 30 μmol m⁻²s⁻¹) was unfavorable to the induction of fertility, but it enhanced female gametophyte division. The optimal conditions for vegetative growth were 15°C and 30 μmol m⁻²s⁻¹. After transplantation of the juvenile seedlings and after eight months cultivation, the harvested mature blade reached 194 cm in length and 32.7 cm in width. Our study proves that it is feasible to implement propagation and large scale cultivation of C. costata in northern China.     

DETERMINATION OF TRACE BENZENE HYDROCARBONS IN JIAOZHOU BAY BY ENRICHMENT AND CAPILLARY COLUMN GAS CHROMATOGRAPHY

Trare amounts of benzene hydrocarbons obtained in Jiaozhou Bay (Qindao) were enriched bysorption on a GDX-102 column and eluted by carbon disulfide. The eluted was concenttaled and then de-temened by capillary column gas cbornatognphy.The contents of virious kinds of benzene hydrocarbons in Jiaozhou Bay coastal water were benzene(22.3-141.6)× 10～(-9)g/L, toluate (15.2-94.0) × 10~(-9) g/L, ethyl benzene(11.8-85.1)×10~(-9) g/L, p -xylene(15.2-78.5) ×10(-9) g/L, m-xylene (10.9-79.4) ×10(-9) g/L, o -xylene (12.4-80.1) x ×10(-9)g/L; iso-propyl(8.4- 73.1) x ×10(-9)g/L, n -propyl (6.9-76.4) ×10(-9) g/L, 1, 3, 5-trimethylbenzene (10.9- 35.9)×10(-9) g/L, 1,2, 4-trimethybenzene (10.0- 38.0)×10(-9) g/L, n - butydriare (8. 1 - 34.6) ×10(-9)g/L. The recovery of benzenehydrocarbons was (85.1 -95.6)%.     

Impact of microzooplankton and Calanus sinicus (Brodsky, 1962) on phytoplankton in the Yellow Sea during early summer

Dilution incubations and Calanus sinicus addition incubations were simultaneously conducted at five stations in the Yellow Sea in June of 2004 to evaluate the impact of microzooplankton and Calanus sinicus on phytoplankton based on the Chlorophyll a (Chl-a) levels. The Chl-a growth rates (k) ranged from 0.60–1.67 d⁻¹, while microzooplankton grazed the Chl-a at rates (g) of 0.29–0.62 d^t-1. The addition of C. sinicus enhanced the Chl-a growth rate (Z) by 0.004–0.037 d⁻¹ ind.⁻¹ L. C. sinicus abundance ranged from 84.1–160.9 ind. m⁻³, which occupied 90.7%–99.1% of the copepod (>500 μm) population. The in-situ increase in phytoplankton by C. sinicus community was estimated to be 0.000 4–0.005 9 d⁻¹. These results showed that microzooplankton were the main grazers of phytoplankton, while C. sinicus induced a slight increase in the levels of phytoplankton.     

Effect of temperature under unfavourable conditions on oxygen uptake of larval herring,Clupea harengus

Oxygen uptake under starvation and short periods of sudden temperature change was measured for larval herring (Clupea harengus L.) reared at average temperature of 7.3, 11 and 12.9°C. Larval stages between first feeding and premetamorphosis were used. For comparison, the routine oxygen uptake (ROU) was also investigated and followed the relationshipQ=0.974+0.174tW ^−0.210, whereQ is in μg/(mg·h),W is dry body weight in mg andt is temperature in °C. The oxygen uptake under starvation (SOU, deprived of food for 24 h) was different from the routine when the larval dry weight was less than 0.6–0.8 mg; it increased with temperature and body weight giving the relationshipQ=1.568+0.110tW ^0.380; if the larval dry weight was more than 0.6–0.8 mg, it reverted to the norm (Q=1.704+0.078tW ^−0.349). The oxygen uptake was tested in short periods (3 h) of sudden temperature changes in six groups: 7.3 to 11, 7.3 to 12.9, 11 to 7.3, 11 to 12.9, 12.9 to 7.3 and 1.29 to 11°C. The oxygen uptake in the 7.3 to 12.9 and 12.9 to 7.3°C groups varied in a way similar to that of the larvae under starvation. The other four groups' oxygen uptake were more or less normal.     

Effects of temperature and irradiance on early development of Chondrus ocellatus Holm (Gigartinaceae, Rhodophyta)

Chondrus is a type of commercially produced red seaweed that widely used for food and carrageen extraction. Although the natural life history of the alga had been well understood, the factors influencing development of the tetraspore and carpospore remain poorly understood. In the perspective of seedling resources, the regulation of early development is crucial for the seedling nursing; therefore, it is necessary to understand the physiological influences during its early development. In this study, we studied the effects of temperature and irradiance on the early development of Chondrus ocellatus Holm under laboratory conditions. The released tetraspores and carpospores were cultivated at different temperatures (10–28°C) and irradiances (10, 60 μmol photons m⁻²s⁻¹) with a photoperiod of 12L:12D. The results indicate that both tetraspores and carpospores are tolerant to temperatures of 10–25°C, and have the highest relative growth rate at 20°C. Irradiance variances influenced the growth of the discoid crusts, and the influence was more significant with increasing temperature; 60 μmol photons m⁻²s⁻¹ was more suitable than 10 μmol photons m⁻²s⁻¹. The optimum temperature and irradiance for the development of seedlings was 20°C and 60 μmol photons m⁻²s⁻¹, respectively.     

Enhanced carotenoid production by a mutant of the marine yeast Rhodotorula sp. hidai

After a serial of UV, EMS and NTG mutagenesis, a mutant named MM of the red marine yeast strain Rhodotorula sp. hidai was obtained. The mutant MM could produce 603.93 μg g⁻¹ of carotenoid within 5 days in the medium containing 4.0 g sucrose, 1.5 g yeast extract, 0.1 g MgSO₄, and 100 mL of sea water, with pH 6.0 and at 30 °C, while only 213.18 μg g⁻¹ of carotenoid was produced by the wild type under the same conditions.     

Standing crop and primary production of benthic microalgae on the tidal flats in Yueqing Bay

The standing stock and primary production of benthic microalgae on tidal flats were measured seasonally at 3 transects (Puqing, Dahengchuang and Puqi) in Yueqing Bay during 2002 2003. The results showed that the integral chlorophyll a (Chl a) concentration in tidal flat mud exhibited a seasonal variation with the order of magnitude: winter (14.0 4.2 mg m-2) > spring (13.0 6.3 mg m-2) > autumn (7.7 5.9 mg m-2) > summer (4.6 3.2 mg m-2). The primary production showed an order of magnitude: spring (270.5 224.9 mgC m-2 d-1)>winter (238.7 225.5 mgC m-2 d-1)>autumn (214.1 56.2 mgC m-2 d-1)>summer (71.6 44.6 mgC m-2 d-1). Both chlorophyll a and primary production showed maximum values in the surface layer of sediment, and decreased rapidly with increasing depth due to sun light limitation. The results of variance analysis indicated that seasonal variation and tidal flat condition affected Chl a greatly, but had no significant effect on primary production. The annual primary production of benthic microalgae on tidal flats in Yueqing Bay was estimated at 16143 tons carbon, which is sufficient to support 1.02×105 tons shellfish production. The environmental factors affecting chlorophyll and primary production on the tidal flats in Yueqing Bay were discussed. By comparing with other bays on China’s coast, it was observed that Yueqing Bay is a region with high benthic microalgae standing crop and primary production, which may be related to the type of its sediment.     

Bioflocculant Produced by Klebsiella sp. MYC and Its Application in the li＇eatment of Oil-field Produced Water

Seventy-nine strains of bioflocculant-producing bacteria were isolated from 3 activated sludge samples. Among them, strain MYC was found to have the highest and stable flocculating rate for both kaolin clay suspension and oil-field produced water. The bacterial strain was identified as Klebsiella sp. MYC according to its morphological and biochemical characteristics and 16SrDNA sequence. The optimal medium for bioflocculant production by this bacterial strain was composed of cane sugar 20 g L^-1, KH2PO4 2 g L^-1, K2HPO4 5 g L^- 1, （ NH4）2SO4 0.2 g L^-1, urea 0.5 g L^- 1 and yeast extract 0.5 g L^- 1, the initial pH being 5.5. When the suspension of kaolin clay was treated with0.5% of Klebsiella sp. MYC culture broth, the flocculating rate reached more than 90.0% in the presence of 500mg L^-1 CaCI2, while the flocculating rate for oil-field produced water was near 80.0% in a pH range of 7.0 - 9.0 with the separation of oil and suspended particles from the oil-field produced water under similar conditions. The environment-friendly nature of the bioflocculant and high flocculating rate of the strain make the bioflocculant produced by Klebsiella sp. MYC an attractive bioflocculant in oil-field produced water treatment.     

A new pullulan-producing yeast and medium optimization for its exopolysaccharide production

1　Introduction　Pullulanstandsforthewater solublehomopolysac charideproducedextracellularlybythe polymorphicmicromyceteAureobasidium pullulans (Yuenetal.,1974 ;Marketal.,1988) .Itisalinearα D glucan ,mademainlyofmaltotrioserepeatingunitsintercon nectedbyα 1,6 linkages.Theregularalternationofα 1,4andα 1,6bondsresultsintwodistinctiveprop ertiesofstructuralflexibilityandenhancedsolubility(Sanjeevetal.,2 0 0 1) .Thispolysaccharideisofeco nomicimportancewithincreasingapplicationinfood ,phar…     

AMMONIUM UPTAKE AND REGENERATION FLUXES OF THE MICROPLANKTON COMMUNITIES IN JIAOZHOU BAY

The results from four cruises(Nov.1991—Jul.1992)to examine fluxes of ammonium uptake andregeneration in the surface layer of Jiaozhou Bay are presented.Seasonal variations of the two fluxeswere in the order:summer>spring>autumn>winter.Diel patterns were characterized by higher uptake inthe daytime and higher regeneration at night.Averaged uptake and regeneration fluxes on an annual scalewere 0.073 and 0.053 μmol·L~(-1)·h~(-1)respectively.Regeneration fluxes were always less than uptakefluxes throughout the year.The longest turnover time was 16.34 d(in winter),and the shortest one was0.68 d(in summer).The major uptake flux was contributed by the smallest fraction-picoplankton.Theextents of light-dependence of ammouium uptake by different size fractions were in the order:netplankton>nanoplankton>picoplankton..     

Effects of heavy metal ions (Cu2+, Pb2+ and Cd2+) on DNA damage of the gills, hemocytes and hepatopancreas of marine crab, Charybdis japonica

There are rising concerns about the hazardous effects of heavy metals on the environment. In this study, comet assay and DNA alkaline unwinding assay were conducted on the tissues (gills, hepatopancreas, and hemocytes) of Charybdis japonica in order to illustrate genotoxicity of three heavy metal ions (Cu2+, Pb2+, and Cd2+) on the marine crabs C. japonica. The crabs were exposed to Cu2+ (10, 50, and 100 ?g.L?1), Pb2+ (50, 250, and 500 ?g L?1) and Cd2+ (5, 25, and 50 ?g L?1), and the tissues were sampled at days 0.5, 1, 3, 6, 9, and 15. DNA alkaline unwinding assay was used for testing the DNA single strand break in gills and hepatopancreas and comet assay was employed for testing the DNA damage in hemocytes. The results showed that the DNA damage (F-value) of gills in the crabs exposed to the three heavy metals was decreased gradually during the exposure periods and there was a dose-time response relationship in certain time, suggesting that the levels of DNA single strand break in all the experimental groups increased significantly compared to the controls. Changes of F-value in hepatopancreas of the crabs exposed to the three heavy metals were similar to those in gills except that the peak values were found in the 500 ?g L?1 Pb2+ treatment group at day 3 and the 50 ?g L?1 Cd2+ treatment group at day 9. The ranks of DNA damage in gills and hepatopancreas induced by the three heavy metal ions (50 ?g L?1, day 15) were Cd2+ >Pb2+ >Cu2+ and Pb2+ >Cu2+ >Cd2+. The levels of DNA damage in gills were higher than those in hepatopancreas in the same experimental group. It can be concluded that indices of DNA damage can be used as the potential biomarkers of heavy metal pollution in marine environment.     

FOOD SOURCES AND CARBON BUDGET OF CHINESE PRAWN PENAEUS CHINENSIS

This study deals with contribution of artificial food pellet and natural food to Chinese prawn (Penaeus orientalis) growth in a semiintensive culture pond. The prawn carbon consumption, budget, and the effects of some factors on the budget were investigated. The results showed that 26.2% of P. orientalis growth carbon came from formulated feed at the initial culture stage (when the prawns were 0.06±0.01 g in wet weight), and was 62.5% when the prawns were 9.56±1.04 g. The remaining part of the growth carbon was derived from organic fertilizer and natural food. The highest growth rate occurred at 20×10-3 salinity. Suitable salinity for culturing Chinese prawn was (20-28)×10-3.     

Abundance and production ofBranchiura sowerbyi (Oligochaeta: Tubificidae) in two typical shallow lakes (Hubei, China)

An April 1996 to March 1997 comparative study on the abundance and secondary production ofBranchiura sowerbyi Beddard, 1892 in two typical shallow lakes showed that in Houhu, an algae-dominated lake, the worm density (68 ind·m⁻²) peaked in July, biomass (1.930 g·m⁻²) peaked in June, while in Biandantang, a macrophyte-dominated lake, standing stock (density: 60 ind·m⁻²; biomass: 1.019 g·m⁻² in wet weight) peaked in December. Secondary production of the animal in Houhu Lake was 3.413 g wet wt m⁻² a⁻¹, a little more than that (2.675 g wet wt m⁻² a⁻¹) in Biandantang Lake. Their turnover rates (P/B ratios) were 4.0 and 5.0, respectively. Project (39600019 and 39430101) supported by NSFC.