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91.
试验采用流水呼吸室法和静水呼吸室法测定了叶尔羌高原鳅在低温6.5~7.5℃条件下的耗氧率和窒息点。结果表明,叶尔羌高原鳅耗氧率具有昼夜节律性,耗氧高峰在5:00左右,低谷在15:00左右,其耗氧率和窒息点随体重的增加而增加,随水温的升高而增大。叶尔羌高原鳅适应低温能力较强,适宜生长温度6~29℃,最佳生长温度8~15℃。 相似文献
92.
机械气浮机通过产生大量丰富细密的雾化气泡,微气泡在垂直上升过程中将水中的悬浮物质粘附去除。通过测定泡沫分离器前后水质指标的变化情况,研究机械气浮装置在半咸水循环水养殖系统中的水质净化效果。结果表明,以机械气浮装置作为主要物理过滤水处理环节,并与鱼池双排水技术结合,在半咸水工况下可以承担主要的物理过滤功能,其总悬浮物(TSS)、化学耗氧量(COD)、总氮(TN)、总磷(TP)和色度的平均去除率分别可达(37.19±12.04)%、(21.89±6.19)%、(30.56±3.62)%、(19.38±5.27)%和(18.66±5.56)%。通过淡水鱼咸水化与泡沫分离技术的有机结合,可有效解决淡水鱼封闭循环水养殖中微小颗粒悬浮物的技术难题,是一种行之有效的方法。 相似文献
93.
Xiaowu LI Zhongjie LI Jiashou LIU Tanglin Zhang Chaowen Zhang 《Aquaculture International》2011,19(2):301-311
A 74-day growth trial was carried out to investigate the effects of light intensity on the juvenile Chinese mitten crab, Eriocheir sinensis, under semi-natural conditions. The experiment had three light intensity treatment groups, natural light (NL), middle light
(ML), and low light (LL), as light intensity became weaker. The results indicated that light intensity had no significant
effect on molting interval and molting frequency but did have a significant effect on the molting weight gain of the crab.
Molting weight gain in group NL was significantly higher than that in group LL (P < 0.05). Specific growth rate in weight (SGRw) and in carapace width (SGRcw), weight gain, and final body weight were significantly
affected by light intensity (P < 0.05). No significant difference was detected in survival between groups (P > 0.05). The precocious rate in groups NL, ML, and LL was 26.14, 15.48, and 17.14%, respectively. The precocious rate in
group NL was significantly higher than that in groups ML and LL (P < 0.05). Chemical composition of the crab body was significantly affected by light intensity, but the activity of alkaline
phosphatase, trypsin, and pancreatic lipase was not significantly affected by light intensity. The results indicated that
the submitted light intensity was useful in reducing the precocious rate without affecting the normal growth of juvenile E. sinensis. 相似文献
94.
The ontogenetic development of the digestive enzymes amylase, lipase, trypsin, and alkaline phosphatase and the effect of
starvation in miiuy croaker Miichthys miiuy larvae were studied. The activities of these enzymes were detected prior to exogenous feeding, but their developmental patterns
differed remarkably. Trypsin activity continuously increased from 2 days after hatching (dah), peaked on 20 dah, and decreased
to 25 dah at weaning. Alkaline phosphatase activity oscillated at low levels within a small range after the first feeding
on 3 dah. In contrast, amylase and lipase activities followed the general developmental pattern that has been characterized
in fish larvae, with a succession of increases or decreases. Amylase, lipase, and trypsin activities generally started to
increase or decrease at transitions from endogenous to exogenous feeding or diet changes, suggesting that these enzymatic
activities can be modulated by feeding modes. The activities of all the enzymes remained stable from 25 dah onwards, coinciding
with the formation of gastric glands and pyloric caecum. These results imply that specific activities of these enzymes underwent
changes due to morphological and physiological modifications or diet shift during larval development but that they became
stable after the development of the digestive organs and associated glands was fully completed and the organs/glands functioned.
Trypsin and alkaline phosphatase were more sensitive to starvation than amylase and lipase because delayed feeding up to 2 days
after mouth opening was able to adversely affect their activities. Enzyme activities did not significantly differ among feeding
groups during endogenous feeding; however, all activities were remarkably reduced when delayed feeding was within 3 days
after mouth opening. Initiation of larvae feeding should occur within 2 days after mouth opening so that good growth and survival
can be obtained in the culture. 相似文献
95.
96.
Sung-Yong Oh Choong Hwan Noh Rae-Seon Kang Chong-Kwan Kim Sung Hwoan Cho Jae-Yoon Jo 《Fisheries Science》2008,74(4):846-852
ABSTRACT: Compensatory growth, feeding rate, feed efficiency and chemical composition of juvenile black rockfish (mean weight 1.43 g) were investigated for 35 days after a 14-day feed deprivation treatment under four feeding conditions: one group continuously fed (control) and the other three groups fasted for 5 days (F5), 10 days (F10) and 14 days (F14). All fasted fish were re-fed from day 15. Only F5 achieved the same body weight as the control, indicating that complete compensation occurred in F5. The specific growth rate (SGR) of F5 was the highest at day 21 and then decreased thereafter, showing higher values than the control at days 21, 28 and 42. In contrast, although SGRs of F10 and F14 were higher than that of the control during the whole refeeding period except day 21, they did not catch up the control in body mass, indicating that only partial compensation occurred in F10 and F14. The feeding rate (FR) of all groups except F14 changed in a pattern similar to SGR (Spearman's rank correlation, r s > 0.9), suggesting that SGR varied depending on FR. Similar feeding efficiencies (FEs) were found in the four groups and they did not vary significantly during the whole refeeding period, suggesting that FE was not the factor affecting SGR. At day 14, the ratios of lipid to lean body mass in F10 and F14 were lower than those in the control and F5, and there was no difference between the control and F5. At day 49, however, only F14 showed a lower value than the other three groups, and there was no difference among the three groups. These results indicate that juvenile black rockfish fasted for 5–14 days can exhibit compensatory growth after refeeding, but timing and degree vary depending on the duration of feed deprivation. 相似文献
97.
98.
Estimation of actual evapotranspiration for a drip-irrigated Merlot vineyard using a three-source model 总被引:3,自引:3,他引:0
A study was performed in order to evaluate the three-source model (Clumped model) for direct estimation of actual evapotranspiration
(ETa) and latent heat flux (LE) over a drip-irrigated Merlot vineyard trained on a vertical shoot positioned system (VSP) under
semi-arid conditions. The vineyard, with an average fractional cover of 30%, is located in the Talca Valley, Region del Maule,
Chile. The performance of the Clumped model was evaluated using an eddy covariance system during the 2006/2007 and 2007/2008
growing seasons. Results indicate that the Clumped model was able to predict ETa with a root mean square error (RMSE), mean bias error (MBE), and model efficiency (EF) of 0.33, −0.15 mm day−1 and 74%, respectively. Also, the Clumped model simulated the daytime variation of LE with a RMSE of 36 W m−2, MBE of −8 W m−2, and EF of 83%. Major disagreement (underestimated values) between observed and estimated values of ETa was found for clear days after rainfall or foggy days, but underestimated values were less than 10% of the data analysis.
The results obtained in this study indicate that the Clumped model could be used to directly estimate vine water requirements
for a drip-irrigated vineyard trained on a VSP. However, application of the Clumped model requires a good characterization
of the drip-irrigated vineyard architecture. 相似文献
99.
100.