At a temperature of 23.0 - 24.8℃, the mixed feeding of Japanese anchovy larvae was initiated 24 h before the yolk-sac was exhausted. The point of no return （PNR） was reached on the 6th day after hatching. On the 4t...At a temperature of 23.0 - 24.8℃, the mixed feeding of Japanese anchovy larvae was initiated 24 h before the yolk-sac was exhausted. The point of no return （PNR） was reached on the 6th day after hatching. On the 4th day after hatching, the pectoral angle appeared in both fed and unfed anchovy larvae although it was more evident and sharper in the starved and the PNR stage larvae than in the fed ones. According to observations of larvae collected in the sea, the pectoral angles were evident not only in the larvae of 3.62 - 7.44 mm in standard length, but also in the larvae of 2.70 mm in standard length with remnants of yolk. The pectoral angles became diffuse when the larvae reached 7.84 mm and vanished at 9.86 mm. The pectoral angle cannot be used as a criterion to distinguish healthy from starving larvae.展开更多
Generally, nutrient cycle is closely related to the element distribution in biomass and the popula- tion dynamics in ecosystems. Carbon, nitrogen and phosphorus in Japanese anchovy （Engraulis japonicus） of different...Generally, nutrient cycle is closely related to the element distribution in biomass and the popula- tion dynamics in ecosystems. Carbon, nitrogen and phosphorus in Japanese anchovy （Engraulis japonicus） of different body lengths from the Huanghai Sea （Yellow Sea） were determined to better understand their variability and reasons during its life history. The mean content was 45.12%, 10.12% and 2.02% for C, N and P, respectively. Significant differences in C, N and P elemental composition were found among different sizes, which could be explained by varying proportions of storage compounds in whole body fish, and varying degrees of ossification. Considering abun- dant resources in Japanese anchovy, it was an important P-pool in the cycle of P. Moreover, the excreted N/P ratio was significantly different in fishes of different sizes, especially at high gross growth efficiency. In the past two decades, overexploitation tended to cause smaller body length in the community structure of anchovy, which presumably changed the nutrient cycle in food webs of the Huanghai Sea. Exptrapolation of the results indicates that Japanese anchovy may be important for conveying nutrient in the Huanghai Sea.展开更多
The effects of cells and cells different fractions of Heterosigma akashiwo on the early development of Engraulis japonicus were studied.The sensitive to algle toxin in the early development of Engraulis japonicus was ...The effects of cells and cells different fractions of Heterosigma akashiwo on the early development of Engraulis japonicus were studied.The sensitive to algle toxin in the early development of Engraulis japonicus was discussed too.The results indicated that the fertilized eggs before blastula and yolk-sac larva of Engraulis japonicus were more sensitive to algle toxin than other development stage.In the same conditions the toxic effect of cell contents on the early development of Engraulis japonicus was highest, cell-free medium was lowest ,algal culture and cell fragments were in the middle.The survival rate was 4% when Engraulis japonicus in the pre-larval-stage was exposed for 96 hours to cell contents at a high concentration of 90 000 cells/ml but the survival rate was 75% when exposed to cell-free medium.LC 50 values at 96 hours exposed to cell contents and cell fragments were 2 818 and 6 760cells/ml.展开更多
The stable carbon isotope compositions of individual amino acids in muscle tissues of the anchovy, Engraulis japonicus, a key species of animal in the Yellow and the East China Sea ecosystem, were determined by the ga...The stable carbon isotope compositions of individual amino acids in muscle tissues of the anchovy, Engraulis japonicus, a key species of animal in the Yellow and the East China Sea ecosystem, were determined by the gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). Eleven amino acid compounds were identified and their δ(13C) values were successfully measured. The new ability to measure stable carbon isotope compositions of individual amino acids offers a potential method for understanding digest, absorption and metabolism of anchovy, Engraulis japonicus, pathway of carbon transfer through food web and evaluating trophic quality of diet.展开更多
On the basis of the data of oceanographic survey in the East China Sea in four seasons during 1997-2000 (23°30'~33°00'N, 118°30'-128°E), the variation of total biomass and diet biomass ...On the basis of the data of oceanographic survey in the East China Sea in four seasons during 1997-2000 (23°30'~33°00'N, 118°30'-128°E), the variation of total biomass and diet biomass of zooplankton and their spatial-temporal distribution and relationship with the fishing ground of Engraulis japonicus are approached and analyzed. The results show that the average biomass is 65.32 mg/m3 in four seasons, autumn (86.18 mg/m3) being greater than summer (69.18 mg/m3) greater than spring (55.67 mg/m3) greater than winter (50.33 mg/m3). The average value of diet zooplankton biomass is 40.9 mg/m3. The trends of horizontal distribution both in the total biomass and the diet biomass of zooplankton are similar. The high biomass region (250-500 mg/m3) is very limited, only accounting for 1% of the investigation area. Seasonal variation of the biomass is very remarkable in the west and north parts of East China Sea coastal waters ( 29°30'N,125°E). The horizontal distribution of diet zooplankton depends on the abundance distribution of crustacean. The distribution of diet zooplankton is related to the fishing ground of Engraulis japonicus and the high-density area of young fish and larval. In spring, the central fishing ground of Engraulis japonicus (>100 kg/h) and the high-density area of young fish and larval (>100 individuals per net) are located at the same place of high-density (100-250 mg/m3)area of diet zooplankton in the middle-southern part of East China Sea or the edge of its waters.展开更多
文摘At a temperature of 23.0 - 24.8℃, the mixed feeding of Japanese anchovy larvae was initiated 24 h before the yolk-sac was exhausted. The point of no return （PNR） was reached on the 6th day after hatching. On the 4th day after hatching, the pectoral angle appeared in both fed and unfed anchovy larvae although it was more evident and sharper in the starved and the PNR stage larvae than in the fed ones. According to observations of larvae collected in the sea, the pectoral angles were evident not only in the larvae of 3.62 - 7.44 mm in standard length, but also in the larvae of 2.70 mm in standard length with remnants of yolk. The pectoral angles became diffuse when the larvae reached 7.84 mm and vanished at 9.86 mm. The pectoral angle cannot be used as a criterion to distinguish healthy from starving larvae.
基金The National Key Basic Research Program from the Ministry of Science and Technology of China under contract Nos 2006CB400601 and 2011CB409801Science Fund for Creative Research Groups of the National Natural Science Foundation of China under contract No.41021064
文摘Generally, nutrient cycle is closely related to the element distribution in biomass and the popula- tion dynamics in ecosystems. Carbon, nitrogen and phosphorus in Japanese anchovy （Engraulis japonicus） of different body lengths from the Huanghai Sea （Yellow Sea） were determined to better understand their variability and reasons during its life history. The mean content was 45.12%, 10.12% and 2.02% for C, N and P, respectively. Significant differences in C, N and P elemental composition were found among different sizes, which could be explained by varying proportions of storage compounds in whole body fish, and varying degrees of ossification. Considering abun- dant resources in Japanese anchovy, it was an important P-pool in the cycle of P. Moreover, the excreted N/P ratio was significantly different in fishes of different sizes, especially at high gross growth efficiency. In the past two decades, overexploitation tended to cause smaller body length in the community structure of anchovy, which presumably changed the nutrient cycle in food webs of the Huanghai Sea. Exptrapolation of the results indicates that Japanese anchovy may be important for conveying nutrient in the Huanghai Sea.
文摘The effects of cells and cells different fractions of Heterosigma akashiwo on the early development of Engraulis japonicus were studied.The sensitive to algle toxin in the early development of Engraulis japonicus was discussed too.The results indicated that the fertilized eggs before blastula and yolk-sac larva of Engraulis japonicus were more sensitive to algle toxin than other development stage.In the same conditions the toxic effect of cell contents on the early development of Engraulis japonicus was highest, cell-free medium was lowest ,algal culture and cell fragments were in the middle.The survival rate was 4% when Engraulis japonicus in the pre-larval-stage was exposed for 96 hours to cell contents at a high concentration of 90 000 cells/ml but the survival rate was 75% when exposed to cell-free medium.LC 50 values at 96 hours exposed to cell contents and cell fragments were 2 818 and 6 760cells/ml.
文摘The stable carbon isotope compositions of individual amino acids in muscle tissues of the anchovy, Engraulis japonicus, a key species of animal in the Yellow and the East China Sea ecosystem, were determined by the gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). Eleven amino acid compounds were identified and their δ(13C) values were successfully measured. The new ability to measure stable carbon isotope compositions of individual amino acids offers a potential method for understanding digest, absorption and metabolism of anchovy, Engraulis japonicus, pathway of carbon transfer through food web and evaluating trophic quality of diet.
基金This study was supported by the National Key Science Foundation Research“973"Project of the Ministry of Science Technology of China under contract No.G19990437.
文摘On the basis of the data of oceanographic survey in the East China Sea in four seasons during 1997-2000 (23°30'~33°00'N, 118°30'-128°E), the variation of total biomass and diet biomass of zooplankton and their spatial-temporal distribution and relationship with the fishing ground of Engraulis japonicus are approached and analyzed. The results show that the average biomass is 65.32 mg/m3 in four seasons, autumn (86.18 mg/m3) being greater than summer (69.18 mg/m3) greater than spring (55.67 mg/m3) greater than winter (50.33 mg/m3). The average value of diet zooplankton biomass is 40.9 mg/m3. The trends of horizontal distribution both in the total biomass and the diet biomass of zooplankton are similar. The high biomass region (250-500 mg/m3) is very limited, only accounting for 1% of the investigation area. Seasonal variation of the biomass is very remarkable in the west and north parts of East China Sea coastal waters ( 29°30'N,125°E). The horizontal distribution of diet zooplankton depends on the abundance distribution of crustacean. The distribution of diet zooplankton is related to the fishing ground of Engraulis japonicus and the high-density area of young fish and larval. In spring, the central fishing ground of Engraulis japonicus (>100 kg/h) and the high-density area of young fish and larval (>100 individuals per net) are located at the same place of high-density (100-250 mg/m3)area of diet zooplankton in the middle-southern part of East China Sea or the edge of its waters.
