Guoqiang Huang

The effect of light color on the growth of Chinese shrimp Fenneropenaeus chinensis

Abstract The specific growth rate (SGR) over 45 days of Fenneropenaeus chinensis shrimp with initial body weight of 1.979±0.036 g under different light color was as follows: natural>green>yellow>blue light. The SGR of shrimp under blue light was only 73.0% and 85.8% of those under natural light and green light, respectively. The maximal and minimal feed intake (FI) of the animal occurred under blue light and yellow light (difference 16.6%), respectively. The lowest food conversion efficiency (FCE) occurred in the blue light group (64.5% and 75.8% of that under natural and green light, respectively). FCE values between blue and natural light groups were significantly different ( P F. chinensis was relatively sensitive to blue light, under which the animal was active in feeding behavior, and gained a higher FI as well as a lower FCE, and therefore, a lower SGR.Shrimp may grow faster in the organically rich earthen ponds than in organically poor waters because there is less blue light spectrum in earthen ponds.

EFFECTS OF SALINITY FLUCTUATION PATTERN ON GROWTH AND ENERGY BUDGET OF JUVENILE SHRIMP FENNEROPENAEUS CHINENSIS

Abstract Experiments were conducted to examine the effects of salinity fluctuation pattern on the intermolt period and growth of Fenneropenaeus chinensis with initial body weight of 1.4510 ± 0.0040 g. The salinity of the control treatment (S0) was 30 ppt throughout the experiment, whereas Treatments S2, S4, S7 and S10 were subjected to different salinity fluctuation pattern with the ranges of ±2, ±4, ±7 and ±10 (ppt), respectively. After the 32-day feeding trial, there were no significant differences in the intermolt periods (P > 0.05); the special growth rates (SGR) under 5 treatments were ranked as S4 > S7 > S2 > S10 > S0, and SGR under treatment S4 was significantly higher than those under treatments S0 and S10 by 58.94% and 37.52%, respectively (P < 0.05). There were no significant differences in feed intake (FI) among all the treatments (P > 0.05). The maximal food conversion efficiency (FCE) occurred in treatment S4, which was significantly higher than those under treatments S0 and S10 by 46.07% and 34.24%, respectively (P < 0.05). Energy budget is also discussed in this article.

Compensatory growth of juvenile brown flounder Paralichthys olivaceus following low temperature treatment for different periods

We investigated the effects of low temperature (8.5°C) on the growth and feeding rates and feed conversion efficiency of juvenile P. olivaceus with an average initial weight of 3.87 ± 0.06 g (mean ± SE). Fish were exposed to 8.5°C for 0 (control), 1, 2, 3 and 4 weeks, and then to 20°C for 10, 9, 8, 7 and 6 weeks, respectively. Low temperature clearly led to growth depression. The weight of fish exposed to low temperature for 1 week was restored to that of control, while that of fish exposed to low temperature longer was significantly decreased (P < 0.05). During the entire low-temperature period, specific growth rate, feeding rate and feed conversion efficiency of the fish were significantly lower (P < 0.05) than those of control, while in the whole recovery period, specific growth and average feeding rate were markedly higher (P < 0.05) than those of control. At the end of experiment, only the feeding rate of the fish exposed to low temperature for 1 week was not significantly different from that of control (P > 0.05). Feeding rate and feed conversion efficiency were reduced at low temperature in juvenile P. olivaceus. The compensatory growth of juvenile P. olivaceus may therefore be attributed to the improvement of feeding rate. Our results suggested that growth depression occurs when juvenile P. olivaceus are exposed to low temperature for more than one week.