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Evaluation of shrimp polyculture system in Thailand based on stable carbon and nitrogen isotope ratios 总被引：1，自引：0，他引：1
HISASHI YOKOYAMA JUNYA HIGANO a KUMIKO ADACHI YUKA ISHIHI YOSHIHIRO YAMADA b 《Fisheries Science》2002,68(4):745-750
ABSTRACT: To quantify the contribution by cocultured animals to waste assimilation in an intensive shrimp farm in Thailand, the food web structures of the macrobenthos in a reservoir pond, a shrimp culture pond and water treatment ponds were examined using the stable C and N isotope ratio technique. Seawater for aquaculture was drawn from a creek, and stored in a reservoir pond, used for farming the banana prawn Fenneropenaeus merguiensis in culture ponds, and then recycled through treatment ponds where the green mussel Perna viridis was cultured to remove organic wastes discharged from the farming. The clam worm Nereididae sp. and the mud creeper Cerithideopsilla cingulata in the culture pond had δ 13 C values of −21.0‰ and −18.4‰, respectively, suggesting that shrimp feed (mean δ 13 C = −20.7‰) was the main food source for these species. The δ 13 C analysis also suggested that sediments (−23.7‰) in the reservoir pond and particulate organic matter (POM) (−24.0‰) and/or sediments (−25.0‰) in the treatment pond supplied carbon for most macrobenthic animals. However, green mussels in the treatment pond had a mean δ 13 C value of −20.5‰, suggesting that shrimp feed was the main food source for this species. 相似文献
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Impact of fish and pearl farming on the benthic environments in Gokasho Bay: Evaluation
from seasonal fluctuations of the macrobenthos 总被引：1，自引：0，他引：1
ABSTRACT: In order to clarify the influence of mariculture on the benthic fauna, samples of the macrobenthos were collected from Gokasho Bay, where intensive fish culture and pearl oyster culture have been carried out. Monthly samples collected from the fish farm and pearl farm sites during June 1995 to July 1996 revealed that the community structure of the two sites showed distinct differences with seasonal fluctuations. At the fish farm site, azoic conditions were found from July to November; after December, the diversity increased markedly through successive recruitments of small-sized species such as the polychaetes Capitella sp. and Pseudopolydora paucibranchiata , and the amphipods Aoroides spp.; macrofaunal density, biomass and species richness peaked from March to April. At the pearl farm site, a higher diversity, including larger-sized species, and no clear seasonal fluctuations in abundance was found, and the community structure was similar to that at the control site. These results show the large impact by fish farming on the macrofauna, whereas pearl farming causes less effect on the benthic fauna. It is suggested that the difference in the level of organic input between the two sites results in the differences in the dissolved oxygen content of the bottom water, sulfide content of the sediments and, subsequently, the macrobenthic assemblages. 相似文献
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Extract of soil under colonies of Hypnum plumaeforme inhibited the growth of roots and shoots of cress, lettuce, lucerne, ryegrass, timothy, Digitaria sanguinalis and Echinochloa crus-galli . Increasing the extract concentration increased the inhibition, which suggest that the soil may contain growth inhibitory substances and possess allelopathic potential. The extract of the soil under H. plumaeforme was purified and two main inhibitory substances were isolated and determined by MS and 1 H- and 13 C-NMR spectral data as momilactone A and B. Momilactone A and B inhibited hypocotyls and roots of cress seedlings at concentrations >10 and 1 μ m respectively. The endogenous concentration of momilactone A and B in H. plumaeforme was 58.7 and 23.4 μg g−1 dry weight respectively and the concentration of momilactone A and B in MS growth medium of H. plumaeforme was 4.3 and 6.4 μg g−1 dry weight of H. plumaeforme , respectively. These results suggest that momilactone A and B were probably secreted into the medium during the incubation and momilactone A and B found in the soil under H. plumaeforme may have been released by the moss. Therefore, growth inhibitory activity of the soil under H. plumaeforme may be caused by momilactone A and B, which may act as allelopathic agents of H. plumaeforme . 相似文献
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ABSTRACT: Four bacteria with degrading activity against the cell walls of Pythium porphyrae were successfully isolated from Porphyra -culturing environments. The crude enzymes from these bacterial isolates, Bacillus sp. BE1, Bacillus sp. FE1, Pseudomonas sp. PE1, and Pseudomonas sp. PE2, degraded the mycelial cell walls of Pythium sp. N -Acetylglucosamine and glucose were detected in the supernatants of Pythium cell walls treated with the enzymes from Bacillus sp. BE1, Bacillus sp. FE1, and Pseudomonas sp. PE2 as the final degrading products by high-performance liquid chromatography, whereas only glucose was detected in the supernatant of the cell walls treated with the enzyme from Pseudomonas sp. PE1. Moreover, the activities of β-1,3-glucanase, β-1,3-1,4-glucanase, and chitinase were observed by polysaccharolytic analysis using the enzymes from Bacillus sp. BE1, Bacillus sp. FE1, and Pseudomonas sp. PE2, whereas only the activities of β-1,3-glucanase and β-1,3-1,4-glucanase were found during analysis using Pseudomonas sp. PE1. β-1,4-Glucanase, β-1,6-glucanase, and mannanase activities were not detected in any of the crude enzymes obtained from these isolates. From the four isolates, the molecular weights (MW) of β-1,3-glucanase and chitinase were estimated to be approximately 50 000–100 000 by the ultrafiltration method. Two Pseudomonas spp. were also suggested to have β-1,3-1,4-glucanases with MW of 50 000–100 000. However, the MW of β-1,3-1,4-glucanases from the two Bacillus spp. might be close to 50 000 or they produce at least two β-1,3-1,4-glucanases with MW of 30 000–50 000 and 50 000–100 000, respectively. 相似文献
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Although d ‐glucose increased the root growth of Arabidopsis seedlings, d ‐allose (a d ‐glucose epimer at the third carbon atom) inhibited the root growth at concentrations >0.1 mmol L?1 and the inhibition increased with increasing d ‐allose concentrations. Allitol (a reduction product of d ‐allose) did not show any significant effect on the growth. The addition of d ‐glucose into the growth medium of Arabidopsis reversed the d ‐allose‐induced growth inhibition, which suggests that the inhibition is not caused by the toxicity of the accumulation of d ‐allose and/or its metabolites in the seedlings. d ‐Allose is phosphorylated by hexokinase, using ATP and phosphate, to allose‐6‐phosphate, with no known capacity for further metabolism. The addition of phosphate into the growth medium did not affect the d ‐allose‐induced growth inhibition and d ‐allose did not reduce the ATP level in the roots. These results suggest that the inhibition is not due to phosphate starvation and ATP depletion. d ‐Mannoheptulose, a specific competitive inhibitor of hexokinase, defeated the d ‐allose‐induced growth inhibition. Hexokinase is known to have a sugar‐sensing function and possibly triggers a signal cascade, resulting in the change of several gene expressions. Therefore, the phosphorylation of d ‐allose by hexokinase might trigger a signal cascade, resulting in the inhibition of Arabidopsis root growth. This is probably a useful model system for studies of the hexokinase‐mediated sugar‐sensing function and for developing new types of weed‐control agents. 相似文献
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