Effects And Mechanism Of Light On The Growth Of Chinese Shrimp, Fenneropenaeus Chinensis

A detailed literature review of ecophysiological effects of light on crustaceans was undertaken, and a series of indoor experiments were conducted to investigate the effects and mechanism of light (including light intensity, light color and photoperiod) on the moult, growth, energy budget and oxygen consumption of Chinese shrimp, Fenneropenaeus chinensis. The results were summarized as follows:2.1 The effect of light color on the growth of Chinese shrimp Fenneropenaeus chinensisThe specific growth rate (SGR&) over 45 days of Fenneropenaeus chinensis shrimp with initial body weight of 1.979?.036 g under different light color was as follows: natural > green > yellow > blue light. The SGRd 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 (FId) of the animal occurred under blue light and yellow light respectively (difference 16.6%). The lowest food conversion efficiency (FCEd) occurred in the blue light group (64.5% and 75.8% of that under natural and green light respectively). FCEd values between blue and natural light groups were significantly different (P<0.05). Fenneropenaeus chinensis was relatively sensitive to blue light, under which the animal was active in feeding behavior, and gained a higher Fid as well as a lower FCEd, and therefore, a lower SGRd. 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.2.2 The effect of light intensity on the growth of Chinese shrimp Fenneropenaeus chinensisThe specific growth rate (SGRd) of juvenile Fenneropenaeus chinensis shrimp over 35 days with an initial body weight of 2.020 ?.015g (mean盨E) under differentlight intensity was as follows: SGROLUX > SGRd 5500LUX- The SG/?d of the shrimp under SSOOLux was only 29.4%, 27.1%, 21.1% and 19.7% of those under OLux, ISOOLux, SOLux and SOOLux, respectively, and there was a significant difference between those under 5500Lux and those under other light intensities (/><0.05). The maximal and minimal feed intake (Flo) of shrimp occurred under 300Lux and 55OOLux respectively (difference 9.3%). The lowest food conversion efficiency (FCEd) occurred in the 55OOLux group (30.2%, 26.3%, 21.3% and 21.1% of those under OLux, 1300Lux, SOLux and 300Lux, respectively). FCEA values between 55OOLux and other groups were significantly different (/*<0.05). The shrimp .under 55OOLux gained a lower FI as well as a lowest FCE, and therefore, exhibited a lower SGR. The results revealed that light intensity affected the growth of the shrimp mainly by influencing FCE, or energy allocation to growth. Therefore, the shrimp may grow better in the organically rich earthen ponds than in organically poor waters, one of the reasons being that there is lower light intensity in pond water.2.3 The effect of photoperiod on the growth of Chinese shrimp Fenneropenaeus chinensisA 35-day feeding experiment was conducted to investigate the effects of photoperiod on the moulting and growth of juvenile Chinese shrimp Fenneropenaeus chinensis. The shrimps with the initial body weight of 0.945 ?.005g (mean盨E) are fed with artificial pellet under four photoperiods(OL:24D> 24L:OD > 14D:10L and 14L:10D).The results of the experiment were shown that there were no significant difference of the specific growth rate (SG/?)> food intake (FI) and food conversion efficiency (FCE) among the shrimps under the four photoperiod treatments (/>>0.05) .while the molting frequency (MF) of the shrimps under 14L:10D and 14D:10L were significantly higher than those under 24L:OD and OL:24D(P<0.05).The photoperiod affected the energy allocation of shrimp in exuviae, so the difference of the molting frequency is significant (.PO.05) while no significantly effect on FI, FCE and the percentages of energy deposited for growth, the growth of the shrimps was not significant (P>0.05 ) . Comparatively to effects of light density and light colour on the growth of Chinese shrimp in shrimp in...