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Cheng B.,CAS Guangzhou Institute of Geochemistry | Du J.,CAS Guangzhou Institute of Geochemistry | Du J.,Guangxi Institute of Oceanology | Tian Y.,CAS Guangzhou Institute of Geochemistry | And 3 more authors.
Energy and Fuels

Organic compounds could be adsorbed and even occluded within the macromolecular structures of kerogen. Studies concerning thermal evolution of adsorbed/occluded hydrocarbons inside kerogens will be helpful in understanding its structural characteristics and evolution features and estimating the effectiveness of adsorbed and occluded fractions. In this work, adsorbed and occluded hydrocarbons have been released from a low-matured kerogen from the upper Permian Lucaogou formation of Santanghu Basin, northwest China, and from its pyrolysis residues by solvent extraction and oxidative treatment, respectively. The results showed that some n-alkanes, terpanes, and steranes were detected from both adsorbed and occluded fractions. Series of even-carbon-numbered n-alk-(1)-enes were also determined from the occluded components. The early stage of thermal evolution showed similarities in biomarker features for both adsorbed and occluded hydrocarbons; however, variations were noted in biomarker compositions with increasing thermal levels. The obvious changes of C21-22 pregnane/C27-29 sterane ratios from adsorbed to occluded fractions at high thermal evolution suggested that high concentrations of pregnane (containing homopregnane) in soluble components in highly or overly mature stage may be mainly derived from the corresponding components covalently bound within kerogen. Occluded components exhibited stronger thermal stability than adsorbed components. This study showed that evaluation of the thermal evolution characteristics of kerogens/source rocks based on biomarkers compositions from the adsorbed components at highly to overly matured stages was difficult, while we hope this kind of assessment of kerogens/source rocks can be achieved from occluded components. © 2016 American Chemical Society. Source

Liu X.,CAS Qingdao Institute of Oceanology | Liu X.,Guangxi Institute of Oceanology | Zhou Y.,CAS Qingdao Institute of Oceanology | Yang H.,CAS Qingdao Institute of Oceanology | Ru S.,Ocean University of China

Eelgrass ecosystems have a wide variety of ecological functions in which living tissues and detritus may be a food source for many marine animals. In this study, we conducted a laboratory simulating experiment to understand the trophic relationship between the eelgrass Zostera marina L and the sea cucumber Apostichopus japonicus. A mixture of decaying eelgrass debris and seafloor surface muddy sediments was used as food to feed A. japonicus, and then specific growth rates (SGR) and fecal production rates (FPR) were measured. According to the proportion of eelgrass debris, we designed five treatment diets, i.e., ES0, ES10, ES20, ES40, and ES100, with eelgrass debris accounting for 0%, 10%, 20%, 40%, and 100% in dry weight, respectively. Results showed that diet composition had a great influence on the growth of A. japonicus. Sea cucumbers could use decaying eelgrass debris as their food source; and when the organic content of a mixture of eelgrass debris and sediment was 19.6% (ES40), a relatively high SGR (1.54%·d-1) and FPR (1.31 g·ind.-1 d-1) of A. japonicus were obtained. It is suggested that eelgrass beds can not only provide habitat for the sea cucumber A. japonicus but can also provide an indirect food source for the deposit feeder. This means that the restoration and reconstruction of eelgrass beds, especially in coastal waters of China, would be a potential and effective measure for sea-cucumber fisheries, in respect to both resource restoration and aquaculture of this valuable species. © 2013 Liu et al. Source

Li J.,CAS South China Sea Fisheries Research Institute | Zhu C.,CAS South China Sea Fisheries Research Institute | Guo Y.,CAS South China Sea Fisheries Research Institute | Xie X.,CAS South China Sea Fisheries Research Institute | And 2 more authors.

Bioturbation by Sipunculus nudus in a fish- Sipunculus polyculture system was investigated using two controlled experiments. The first experiment was conducted in 20 breeding tanks (water volume 550. L) in which unfed S. nudus (mean weight 1.2 ±. 0.1. g) were stocked in the bottom sandy sediment at four different densities: 0 (control), 50, 100 and 150 individuals per tank. In each tank, 3 juvenile Mugil cephalus (mean weight 24.5 ±. 0.5. g) were cultured with a normal ration supply in a net cage (diameter 0.8. m, height 0.6. m) suspended in the seawater above. The experiment was conducted for 60. d. The second experiment, which was conducted for 20. d, quantified the transportation ability of S. nudus on the surface sediment. S. nudus (mean weight 1.3 ±. 0.1. g) were stocked in the sandy sediment in 25 aquaria (31. cm ×. 20. cm ×. 30. cm) at five densities (0, 4, 8, 12 and 16 individuals per aquarium). The sediment was prepared in layers: the bottom layer was a 6-cm-thick layer of medium sand (grain size 0.40-1.10. mm), and the top layer was a 1-cm-thick layer of fine sand (grain size 0.10-0.28. mm).In the first experiment, 1) S. nudus exhibited excellent survival in all experimental groups, but positive weight gain was only observed in the low-stocking-density group (50 individuals per tank); the best M. cephalus growth also occurred in this group (P<0.05). 2) The control group without S. nudus had the highest organic matter content (2.301mgg-1) in the surface sediment and the highest oxidation reduction potential of the pore water in the bottom layer (P<0.05) among the groups at the end. 3) Visual inspection and variations of POM content in the sediment indicated that S. nudus could promote the transportation of surface sediment to the bottom. The second experiment demonstrated the transportation ability of S. nudus on the surface sediment, and the transportation rates were significantly higher in the treatments with high S. nudus densities of 12 and 16 individuals per aquarium compared to those stocked with lower S. nudus densities (P<0.05).The above results indicate that S. nudus can mitigate sediment organic waste accumulation in an aquaculture system by transporting surface sediment to the bottom; thus, the polyculture of S. nudus with other aquaculture animals is both ecologically and economically feasible. © 2014 Elsevier B.V. Source

Sun X.-P.,Ocean University of China | Sun X.-P.,Guangxi Institute of Oceanology | Cao F.,Ocean University of China | Shao C.-L.,Ocean University of China | And 3 more authors.
Chemistry and Biodiversity

Three new Δ1-3-ketosteroids characterized with a 9-OH, subergosterones A-C (1-3), together with five known analogs 4-8, were obtained from the gorgonian coral Subergorgia rubra collected from the South China Sea. The structures of 1-3, including their absolute configurations, were determined by comprehensive spectroscopic methods and electronic circular dichroism (ECD) experiments. Compounds 2 and 3 exhibited inhibitory antibacterial activities against Bacillus cereus with MIC values of 1.56 μM. © 2015 Verlag Helvetica Chimica Acta AG, Zürich. Source

Zhang Q.,Guangxi Institute of Oceanology | Yu H.,Weifang University | Tong T.,Guangxi Institute of Oceanology | Tong W.,Guangxi Institute of Oceanology | And 3 more authors.
Fish and Shellfish Immunology

A feeding trial was conducted to investigate the effects of dietary administration of probiotic Bacillus subtilis and prebiotic fructooligosaccharide (FOS) on growth performance, immune responses and disease resistance of juvenile ovate pompano, Trachinotus ovatus. One thousand six hundred and twenty individuals (initial body weight: 10.32±0.46g, mean±S.E) were fed nine practical diets according to a 3×3 factorial design: the basal diet as the control diet supplemented with three levels of B.subtilis (0, 1.05×107 or 5.62×107CFUg-1 diet), crossed with 0, 0.2% or 0.4% FOS. After an 8-week feeding experimental period, six fish per cage were sampled for immunity determination. Then 18 fish of each cage left were challenged by Vibrio vulnificus. The results showed that fish fed with 5.62×107CFU B.subtilis g-1 in combination with 0.2% FOS produced the highest specific growth rate, and were significantly higher than the groups fed with 0 and 0.2% FOS without B.subtilis supplementation (P<0.05). Feed efficiency ratio significantly increased with the increasing doses of dietary FOS without B.subtilis added (P<0.05). The immune assay showed that fish fed with the control diet produced the lowest respiratory burst activity and was significantly different from the groups fed the diets containing 0.2% FOS at each B.subtilis level and containing 0.4% FOS single (P<0.05). Phagocytic activity was significantly decreased with the increasing doses of dietary B.subtilis at 0.4% FOS level (P<0.05). Alternative complement pathway activity of the fish fed with 0.2% FOS single was significantly lower than those fed with 5.62×107CFU B.subtilis g-1 diet supplemented at each FOS level (P<0.05). Fish fed with the control diet had the lowest lysozyme activity, and were significantly different from those fed with 0.2 or 0.4% FOS at 1.05 and 5.62×107CFU B.subtilis g-1 diet level. Moreover, fish fed with diets supplemented with 0.2% and 0.4% FOS at each B.subtilis level had notably lower cumulative mortality after 10 days following V.vulnificus infection (P<0.05). Under the experimental conditions, dietary B.subtilis and FOS had a significant interaction on enhancing the immune responses and disease resistance of juvenile ovate pompano (P<0.05). © 2014 Elsevier Ltd. Source

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