Effects of different diets on the reproduction and naupliar development of the copepod Acartia bifilosa

The influence of diatoms on the reproduction and naupliar development of Acartia bifilosa was investigated under laboratory conditions, comparing initial in situ values and laboratory-food treatments. Egg production by A. bifilosa was significantly reduced by one diatom diet (Phaeodactylum tricornutum: Pt) and by two non-diatom diets (Platymonas subordiformis: Ps and Nannochloropsis oculata: No). It was less affected by the other diatom diet (Skeletonema costatum: Sc) or by two mixed-food treatments (D-mix and DG-mix), composed of two diatoms (Pt, Sc) and four species (Pt, Sc, Ps and No), respectively. The negative effect of Pt was eliminated when adult copepods were offered mixed-food diets. There were no significant differences between the hatching success values observed in filtered seawater and in algal exudates, indicating that diatoms did not produce active dissolved toxic substances under the different food concentrations tested. The mortality rate of nauplii was higher with Pt than the other diets, suggesting that this diatom species had a negative effect on egg production, hatching success and naupliar survival simultaneously. Compared to other diets, No and Pt were not beneficial food sources for reproduction and for female and larval survival. (c) 2007 Elsevier B.V. All rights reserved.

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 mu g L-1 and 0.41-10.43 mu g L-1 inside and outside the river mouth, with the mean value 0.73 mu g L-1 and 1.86 mu g 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 mu g L-1 at station 18 (122.67 degrees E, 31.25 degrees N), and the region of high Chl-a concentration was observed in the central survey area between 122.5 degrees E and 123.0 degrees E. In the stations located east of 122.5 degrees 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 mu m and < 20 mu m was 0.28 mu g L-1 and 1.40 mu g L-1, respectively. High Chl-a concentration of < 20 mu m 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.

Ecological environment changes in Daya Bay, China, from 1982 to 2004

Data collected from 12 marine monitoring stations in Daya Bay from 1982 to 2004 reveal a substantial change in the ecological environment of this region. The average N/P ratio increased from 1.377 in 1985 to 49.09 in 2004. Algal species changed from 159 species of 46 genera in 1982 to 126 species of 44 genera in 2004. Major zooplankton species went from 46 species in 1983 to 36 species in 2004. The annual mean biomass of benthic animals was recorded at 123.10 gm(2) in 1982 and 126.68 g m(2) in 2004. Mean biomass and species of benthic animals near nuclear power plants ranged froth 317.9 g m(2) in 1991 to 45.24 g m(2) in 2004 and from 250 species in 1991 to 177 species in 2004. A total of 12-19 species of hermatypic corals and 13 species of mangrove plants were observed in Daya Bay from 1984 to 2002. 2008 Elsevier Ltd. All rights reserved.

Responses of a coastal phytoplankton community to increased nutrient input from the Changjiang (Yangtze) River

Nutrient input from the Changjiang River (Yangtze River) has been increasing dramatically since the 1960s. At the mouth of the Changjiang River, the nitrate concentration has increased about three-fold in 40 years, from 20.5 mu mol/L in the 1960s to 59.1 mu mol/L in the 1980s and to 80.6 mu mol/L in 1990-2004. Phosphate concentration increased by a factor of 30%, from 0.59 mu mol/L in the 1980s to 0.77 mu mol/L in 1990-2004. The increasing nitrate input has arisen mostly from the mid and lower reaches of the Changjiang River, where the river meets one of the most strongly developed agriculture areas in China. Responses of the coastal phytoplankton community to the increasing nutrient inputs are also seen in the available monitoring data. First, a trend of increasing phytoplankton standing stock from 1984 to 2002 appeared in the Changjiang River estuary and adjacent coastal waters, especially in late spring. Secondly, the proportion of diatoms in the whole phytoplankton community showed a decreasing trend from about 85% in 1984 to about 60% in 2000. Finally, red tides/harmful algal blooms increased dramatically in this area in terms of both number and scale. About 30-80 red tide events were recorded each year from 2000 to 2005 in the East China Sea. The scale of some blooms has been in excess of 10,000 km(2). (c) 2008 Elsevier Ltd. All rights reserved.

The status and characteristics of eutrophication in the Yangtze River (Changjiang) estuary and the adjacent East China Sea, China

Eutrophication has become increasingly serious and noxious algal blooms have been of more frequent occurrence in the Yangtze River Estuary and in the adjacent East China Sea. In 2003 and 2004, four cruises were undertaken in three zones in the estuary and in the adjacent sea to investigate nitrate (NO3-N), ammonium (NH4-N), nitrite (NO2-N), soluble reactive phosphorus (SRP), dissolved reactive silica (DRSi), dissolved oxygen (DO), phytoplankton chlorophyll a (Chl a) and suspended particulate matter (SPM). The highest concentrations of DIN (NO3-N+NH4-N+NO2-N), SRP and DRSi were 131.6, 1.2 and 155.6 mu M, respectively. The maximum Chl a concentration was 19.5 mg m(-3) in spring. An analysis of historical and recent data revealed that in the last 40 years, nitrate and SRP concentrations increased from 11 to 97 mu M and from 0.4 to 0.95 mu M, respectively. From 1963 to 2004, N:P ratios also increased from 30-40 up to 150. In parallel with the N and P enrichment, a significant increase of Chl a was detected, Chl a maximum being 20 mg m(-3), nearly four times higher than in the 1980s. In 2004, the mean DO concentration in bottom waters was 4.35 mg l(-1), much lower than in the 1980s. In comparison with other estuaries, the Yangtze River Estuary was characterized by high DIN and DRSi concentrations, with low SRP concentrations. Despite the higher nutrient concentrations, Chl a concentrations were lower in the inner estuary (Zones 1 and 2) than in the adjacent sea (Zone 3). Based on nutrient availability, SPM and hydrodynamics, we assumed that in Zones 1 and 2 phytoplankton growth was suppressed by high turbidity, large tidal amplitude and short residence time. Furthermore, in Zone 3 water stratification was also an important factor that resulted in a greater phytoplankton biomass and lower DO concentrations. Due to hydrodynamics and turbidity, the open sea was unexpectedly more sensitive to nutrient enrichment and related eutrophication processes.

Impacts of HAB species Heterosigma akashiwo on early development of the scallop Argopecten irradians Lamarck

The effects of Heterosigma akashiwo on the early development of Argopecten irradians Lamarck: eggs, D-shaped larvae, eye-spot larvae and juveniles, were investigated under laboratory conditions. Exposing fertilized eggs to various densities of H. akashiwo algal culture revealed that the development of the embryos to the gastrula was significantly slowed at densities of more than 1 X 10(4) cells/ml algal cells, and mostly was arrested when the embryos reached the trochophore larvae stage. At this stage, several trochophore larvae were adhered together by the algal cells, resulting in the inhibition of their swimming activity. Larvae had still not developed into D-shaped larvae after 30 h, and therefore did not finish the hatching process. The attachment and adherence of the algal cells to the larvae might be an important process in the mechanism of the impact on egg hatching success. The activity of the D-shaped larvae was significantly inhibited after 48 h exposure to H. akashiwo at a density of 15 X 10(4) cells/ml and after 96 h at 10 X 10(4) cells/ml. The survival rate of the eye-spot larvae was decreased significantly after 48 h exposure to the algal culture at densities of more than 1 X 10(4) cells/ml. However, all the juveniles could survive and their climbing and attachment activity were not affected after 1 and 5 h exposure to the algal culture at all the various algal cell densities tested from 5 to 20 X 10(4) cells/ml. The results indicated that susceptibility of embryos or larvae to the alga H. akashiwo differs depending on the developmental stage. The embryos and the eye-spot larvae of A. irradians are more sensitive stages to the toxicity of H. akashiwo. Observed effects of H. akashiwo exposure on early development of A. irradians serve to point out to the potential danger of this alga for scallop populations. The possible toxicological mechanisms of H. akashiwo on the scallop embryos and larvae are discussed. (c) 2005 Elsevier B.V All rights reserved.

Feeding habits of Calanus sinicus (Crustacea : Copepoda) during spring and autumn in the Bohai Sea studied with the herbivore index

Pigment ingestion rate (PIR) and egg production rate (EPR) of the dominant copepod Calanus sinicus, as well as chlorophyll-a concentration and phytoplankton assemblages were measured in the Bohai Sea, North China in June 1997, October 1998 and May 1999. A herbivore index (H) was also calculated as the carbon specific ratio of PIR and EPR, in order to investigate its feeding habits in the spring and autumn phytoplankton bloom respectively. On average, chlorophyll-a concentration was relatively similar (1-1.34 mg m(-3)) in the three cruises, but PIR was quite different. It was 3.24 mu g C female(-1) d(-1) in October, equivalent to one half of the PIR for June and one third of the PIR for May. Average EPR was highest in May, and quite similar during the other two months. According to H values, herbivorous feeding contributed 100% of the egg production of C. sinicus in June, 82.5% in May, but only 47.8% in October. It is possible that omnivorous feeding of C. sinicus in October was induced by a prevalence of large-sized diatoms and sufficient non-phytoplankton food resources during the autumn bloom period.

Two new species of Family Prasiolaceae (Prasiolales, Chlorophyta) from China Sea

Amomg the 30 known species of the algal family Prasiolaceae (Prasiolales, Chlorophyta), nine marine species have been found in marine environments but none in China seas. We reported here two new species Prasiola fangchengensis Luan et Ding sp. nov. and Prasiola volcanica Luan et Ding sp. nov. from subtropical coastal water of southern China.

Biosorption of Cr(VI) from aqueous solutions by nonliving green algae Cladophora albida

Biosorption of Cr(VI) from aqueous solutions by nonliving green algae Cladophora albida was investigated in batch experiments. The influence of pH, algal dosage, initial Cr(VI) concentration, temperature and coexisting anions on removal efficiencies of C. albida was studied. Cr(VI) removal process was influenced significantly by the variation of pH, and the optimum pH was chosen at a range of 1.0-3.0. The optimum algal dosage 2 g/L was used in the experiment. The removal rate of Cr(VI) was relatively rapid in the first 60 min, but then the rate decreased gradually. Removal mechanism was studied by analyzing Cr(VI) and total Cr in the solution. Biosorption and bioreduction were involved in the Cr(VI) removal. Biosorption of Cr(VI) was the first step. followed by Cr(VI) bioreduction and Cr(III) biosorption on the algal biomass. Actual industrial wastewater was used to evaluate the practicality of the biomass C. albida. From a practical viewpoint, the abundant and economic biomass C. albida could be used for removal of Cr(VI) from wastewater by the reduction of toxic Cr(VI) to less toxic Cr(III). (C) 2008 Elsevier Ltd. All rights reserved.

Prevention of fish oil rancidity by phlorotannins from Sargassum kjellmanianum

Known only in the Phaeophyceae, phlorotannins (brown algal polyphenols) are a class of natural products with potential uses in pharmacology. This study reports that phlorotannins from Sargassum kjellmanianum can prevent fish oil from rancidification; the antioxidation activity was about 2.6 times higher than that of 0.02% BHT (tertbutyl-4-hydroxytoluene).

The characteristics of nutrient removal and inhibitory effect of Ulva clathrata on Vibrio anguillarum 65

To investigate the ecological effect of macroalgae on de-eutrophication and depuration of mariculture seawater, the variation of dissolved inorganic nitrogen (DIN) and phosphate (DIP), the amount of Vibrio anguillarum, and total heterotrophic bacteria in Ulva clathrata culture, as well as on the algal surface, were investigated by artificially adding nutrients and V. anguillarum strain 65 from February to April 2006. The results indicated that U. clathrata not only had strong DIN and DIP removal capacities, but also showed a significant inhibitory effect on V. anguillarum, although not reducing the total heterotrophic bacteria. Vibrio anguillarum 65 dropped from 5 similar to 8 x 10(7) cfu mL(-1) to 10 cfu mL(-1) (clone-forming units per mL) in 10 g L-1 of fresh U. clathrata culture within 2 days; i.e., almost all of the Vibrios were efficiently eradicated from the algal culture system. Our results also showed that the inhibitory effect of U. clathrata on V. anguillarum strain 65 was both DIN- and DIP-dependent. Addition of DIN and DIP could enhance the inhibitory effects of the algae on the Vibrio, but did not reduce the total heterotrophic bacteria. Further studies showed that the culture suspension in which U. clathrata was pre-cultured for 24 h also had an inhibitory effect on V. anguillarum strain 65. Some unknown chemical substances, either released from U. clathrata or produced by the alga associated microorganisms, inhibited the proliferation of V. anguillarum 65.

塔里木盆地寒武－奥陶系白云岩类型、成因机理及其孔隙性研究

Cambrian-Ordovician dolostones in Tarim Basin are hydrocarbon reservoir rocks of vital importance. Under the guidance of the theories of sedimentology and the sedimentology of carbonate reservoir, based on the first-hand qualitative and quantitative data especially, combined with micro-study, geochemical and reservoir capacity analysis, and precursor research, the origin and reservoir characteristics of the dolostones were discussed. Based on detailed petrographic investigations, four types of dolostone have been recognized, which are, respecitively, mud-silt-sized dolostones, algal laminated dolostones (ALD), prophyritic dolostone, and neomorphic dolostone. Mud-silt-sized dolostones always presents as laminas together with evaporated signatures, its REE patterns and ΣREE are all close to that of the finely crystalline limestone. This kind of dolomite probably experienced relatively low fluid-rock ratio during diagenesis was formed in hypersaline and oxidizing environment and involved fast dolomitization process. It was dolomitized by evaporated seawater in sabkha environment.The main primary fabrics of algal lamination in algal laminated dolomite (ALD) can still be identified and its ΣREE (21.37) is very close to that of algae. This reveals that ALD was dolomitized during early diagenesis and algae possibly played an important role. The ALD was formed under mediation of organic matter and Mg2+ were supplied by magnesium concentrated algal laminites and sea water. Prophyritic dolostones presents mainly as patchy occurrence and yield the lowest δ13C and Z value. Its ΣREE is much less than that of the finely crystalline limestone. These characteristics reveal that the cloudy cores were dolomitized in shallow early diagenetic environments by pore fluids riched in Mg2+. Whereas the clear rims were likely formed in subsequent burial into deeper subsurface environments, and the Mg2+ needed for further dolomitization possibly was supplied by the transformations of clay minerals. Neomorphic dolostones consist of coarse, turbid crystals and exhibits sucrosic and mosaic textures. It has highest Fe2+ contents and average homogeneous temperature (110.2℃). Collectively, these characteristics demonstrate that the neomorphic dolostones was likely formed by recrystallization of pre-existing dolomites during deep burial. The ΣREE of the four types of dolostone distinctly differentiates from each other. However, their REE patterns are all enriched in LREE, depleted in HREE and have Eu negative anomalies. Its ΣREE 13.64 ppm, less than 1/4 of finely crystalline limestone, and ranks the lowest in the 4 types.These characteristics are comparable to those of finely crystalline limestone, and are mainly infuenced by the sea water. These four types of dolostone show similar REE mobility behaviour and no significant fractionation, althouth they have been subjected to evidently different diageneses. Seven main pore types are identified in the dolostones , which are fenestral, moldic, intercrystal, dissolved，breccia, dissolved breccia and stylolite pores. Fenestral pores are primary and the others are secondary. The dissolved pores and intercrystal pores are the most important reservoir spaces and followed by breccias and dissolved breccia pores, and the moldic and fenestral pores are less important. Stylolites can enhance permeability of reservoir rocks in one hand, for the other hand, the capacity of reservoir and permeability are enhanced and then better reservoir rocks can be formed when they are combined with patchy dolostones. The relationship between porosity and the type of dolostones is that the dissolved neomorphic dolostones have the highest porosity of 3.65%, than followed by dissolved Mud-silt-sized dolostones of 3.35%. The mud-silt-sized dolostones without dissolution have the lowest porosity of 0.90%. Moreover, the porosity of prophyritic dolostones and the neomorphic dolostones without dissolution are lower, respectively 1.675% and 1.41%. Although algal laminated dolostones consist of euhedral crystals and riched in intercrystal pores, its porosity just yields 1.20%. The relationship between permeability and the type of dolostones is that that algal laminated dolostones have the highest permeability of 0.462mD and followed by 0.065mD of prophyritic dolostones. Dissolution have no significant influence on the permeability of neomorphic dolostones and this presented by the permeability of dissolved and non-dissolved are very close, respectively 0.043mD and 0.062mD. No matter dissolved or not, mud-silt-sized dolostones are much less permeable. The permeability of non-dissolved and dissolved are 0.051mD and 0.016mD. Collectively, in the study area, neomorphic dolostones can form high quality reservoir.

宣龙式赤铁矿含矿岩系的成矿过程研究

Xuanlong-type Hematite Deposits, distributed in Xuanhua and Longguang area in Hebei province and hosted in the Changchengian Chuanlinggou Formation of Mesoproterozoic, is an oldest depositional iron deposit characterized by oolitic and stromatolitic hematite and siderite. This thesis made an systematic study of its sedimentary, sedimentology, geochemistry, mineralogy and sequence stratigraphy. Based on above, the mechanism and background of biomineralization are discussed. There are four types of hematite ores including stromatolite, algal oolite, algal pisolite and oncolite. Based on detailed study on ore texture, the authors think both algal oolite and algal pisolite ores are organic texture ores, and related to the role of microorganisms. The process of blue-green algae and bacteria in the Xuanlong basin absorbing, adsorbing and sticking iron to build up stromatolite is the formation process of Xuanlong-type hematite deposit. Researches on ore-bearing series and ore geochemistry show that the enrichment of elements is closely related to the microorganism activities. Fe_2O_3 is enriched in dark laminations of stromatolite with much organic matter and SiO_2 in light laminations with detrital matters. The trace elements, especially biogenic elements, including V, P, Mo are enriched in ores but relatively low in country rocks. The paper also demonstrates on the sequence stratigraphy of hematite deposits and five sequences and twelve systems are divided. The characteristics of sequence stratigraphy show that the deposit-forming location has obviously selectivity and always exists under a transgressive setting. The oxygen isotope in hematite is about -2.2～5.7‰, which is similar to that of Hamlys iron formation of Australia but more negative than that of volcanic or hydrothermal iron deposits characterized by high positive values. The calculation by the result of oxygen isotope analysis shows that the temperature of ancient sea water was 48.53℃. The negative value of carbon isotope from siderite indicates its biogenic carbon source. Meanwhile, the occurrence of seismite in the ore-beds, which indicates the formation of hematite deposits is associated with frequent shock caused by structural movement such as distal volcano or ocean-bottom earthquake etc, show the occurrence of hematite deposits is eventual, not gradual. In shorts, Xuanlong-type hematite deposits were the result of interaction among geological setting of semi-isolated Xuanglong basin, favorable hot and humid climate condition, abundant iron source, microorganism such as algae and bateria as well as the fluctuation of the sea level.

珠江口盆地流花11-1油田储层非均质性及流体分布规律研究

In order to discover the distribution law of the remaining oil, the paper focuses on the quantitative characterization of the reservoir heterogeneity and the distribution law of the fluid barrier and interbed, based on fine geological study of the reservoir in Liuhuall-1 oil field. The refined quantitative reservoir geological model has been established by means of the study of core analysis, logging evaluation on vertical well and parallel well, and seismic interpretation and prediction. Utilizing a comprehensive technology combining dynamic data with static data, the distribution characteristics, formation condition and controlling factors of remaining oil in Liuhuall-1 oil field have been illustrated. The study plays an important role in the enrichment regions of the remaining oil and gives scientific direction for the next development of the remaining oil. Several achievements have been obtained as follows: l.On the basis of the study of reservoir division and correlation,eight lithohorizons (layer A, B_1, B_2, B_3, C, D, E, and F) from the top to the bottom of the reservoir are discriminated. The reef facies is subdivided into reef-core facies, fore-reef facies and backreef facies. These three subfacies are further subdivided into five microfacies: coral algal limestone, coralgal micrite, coral algal clastic limestone, bioclastic limestone and foraminiferal limestone. In order to illustrate the distribution law of remaining oil in high watercut period, the stratigraphic structure model and sedimentary model are reconstructed. 2.1n order to research intra-layer, inter-layer and plane reservoir heterogeneity, a new method to characterize reservoir heterogeneity by using IRH (Index of Reservoir Heterogeneity) is introduced. The result indicates that reservoir heterogeneity is medium in layer B_1 and B_3, hard in layer A, B_2, C, E, poor in layer D. 3.Based on the study of the distribution law of fluid barrier and interbed, the effect of fluid battier and interbed on fluid seepage is revealed. Fluid barrier and interbed is abundant in layer A, which control the distribution of crude oil in reservoir. Fluid barrier and interbed is abundant relatively in layer B_2,C and E, which control the spill movement of the bottom water. Layer B_1, B_3 and D tend to be waterflooded due to fluid barrier and interbed is poor. 4.Based on the analysis of reservoir heterogeneity, fluid barrier and interbed and the distribution of bottom water, four contributing regions are discovered. The main lies on the north of well LH11-1A. Two minors lie on the east of well LH11-1-3 and between well LH11-1-3 and well LH11-1-5. The last one lies in layer E in which the interbed is discontinuous. 5.The parameters of reservoir and fluid are obtained recurring to core analysis, logging evaluation on vertical well and parallel well, and seismic interpretation and prediction. Theses parameters provide data for the quantitative characterization of the reservoir heterogeneity and the distribution law of the fluid barrier and interbed. 6.1n the paper, an integrated method about the distribution prediction of remaining oil is put forward on basis of refined reservoir geological model and reservoir numerical simulation. The precision in history match and prediction of remaining oil is improved greatly. The integrated study embodies latest trend in this research field. 7.It is shown that the enrichment of the remaining oil with high watercut in Liuhua 11-1 oil field is influenced by reservoir heterogeneity, fluid barrier and interbed, sealing property of fault, driving manner of bottom water and exploitation manner of parallel well. 8.Using microfacies, IRH, reservoir structure, effective thickness, physical property of reservoir, distribution of fluid barrier and interbed, the analysis of oil and water movement and production data, twelve new sidetracked holes are proposed and demonstrated. The result is favorable to instruct oil field development and have gotten a good effect.

Strategies that students use to trace code: an analysis based in grounded theory

Fitzgerald, S., Simon, B., and Thomas, L. 2005. Strategies that students use to trace code: an analysis based in grounded theory. In Proceedings of the First international Workshop on Computing Education Research (Seattle, WA, USA, October 01 - 02, 2005). ICER '05. ACM, New York, NY, 69-80