The Research Of Effects Of Light On The Behevior、 Respiratory Metabolism And Growth Of Portunus Trituberculatus

1The basic research of effect of light on thePhototatic of swimming crab（Portunus trituberculatus）In this experiment the phototatic ratio of swimming crab （Portunustrituberculatus）to study under different light color. The results reveal as follows:1.Phototactic of the crab under the different light color in the same light intensityrange was significantly different. The phototatic ratio under red light was highest aswell as under yellow light lowest. The phototatics ratio between red and yellow weresignificantly different（P＜0.05）.2.The distribution of the crab in a single light colorwas different: The phototatic ratio of different light range had no significantdifference（P＞0.05）. Marked differences were found in phototatic ratio of lightranges under red and blue light（P＜0.05）. The phototatic ratio decreases with lightintensity. at white and blue light Under the yellow light, the phototatic ratio indifferent light ranges is significantly different, but the minimum value occurred in328～340lx light range. In conclusion, the phototatic ratio of yellow light was least inthe same light range; the distribution in different ranges of yellow was relativelyuniform. Considering the results of growth and respiratory, Portunus trituberculatusgrow better and had a low cannibalism in factory culture. 2Effects of light on the respiratory metabolism of swimmingcrab（Portunus trituberculatus）2.1Effects of light intensity on the respiratory metabolism ofswimming crab（Portunus trituberculatus）Indoor experiments were conducted to investigate the effect of constant lightintensity on physiology and ecology characteristic of swimming crab（Portunustrituberculatus）. The oxygen consumption rat（eOCR), ammonia excretion rate（AER),O:N ratio, lactic acid（LD), energetic contents in hemolymph and respiratory enzymeactivities including hexokinase （HK）， pyruvate kinase （PK）， succinatedehydrogenase（SDH） and lactate dehydrogenase（LDH)were tested in five constantlight intensity treatments（0lx,200lx,800lx,1500lx,3500lx). The main resultswere as follows:1, Light intensity influenced the OCR and AER significantly(P＜0.05). The oxygen consumption rate of the crab under200-1500lx was significantlyhigher than those of the crab under0lx and3500lx（P<0.05） The ammonia excretionrate of the crab under1500lx was significantly lower than others （P<0.05）.2. Lightintensity influenced total protein, but did not influence other energetic contents andO:N ratio significantly(P＞0.05). Our result suggest that protein are usedpreferentially as energy source.3. Marked differences were found in LD(P＜0.05).The LD in muscle of the crab under1500lx was lowest.4. Different light intensitiesinfluence different respiratory enzymes differently. Under1500lx, the activity of HKand PK were at a high level. Glycolysis were at a high lever, and produce more energyThe activity of SDH was in a high level as well as LDH was low. Aerobic metabolismwas active, providing more energy for a continuous motion of crab In conclusion，respiratory metabolism was affected by light intensity, and the crab at1500lx hadhigher metabolism. So about1500lx maybe the better illumination condition of the 2.2Effects of light color on the respiratory metabolism ofswimming crab（Portunus trituberculatus）Indoor experiments were conducted to investigate the effect of light color onphysiology and ecology characteristic of swimming crab（Portunus trituberculatus）.The oxygen consumption rate（OCR), ammonia excretion rate（AER), O:N ratio,lactic acid（LD), energetic contents in hemolymph and respiratory enzyme activitiesincluding hexokinas（eHK），pyruvate kinas（ePK），succinate dehydrogenas（eSDH）and lactate dehydrogenase（LDH)were tested in five light color treatments（white,blue, red, yellow, green). The main results were as follows:1, Light colorinfluenced the OCR significantly(P＜0.05). The oxygen consumption rate of the crabunder blue was significantly higher than those of the crab under other colors（P<0.05）The ammonia excretion rate of the crab was not significantly different （P<0.05）.2.Light color influenced total protein, but did not influence other energetic contents andO:N ratio significantly(P＞0.05). Our result suggest that protein are usedpreferentially as energy source.3. Marked differences were found in LD(P＜0.05).The LD in muscle of the crab under yellow light was lowest.4. Different lightintensities influence different respiratory enzymes differently. Under yellow light, theactivity of HK and PK were at a high level. Glycolysis went faster and produce moreenergy The activity of SDH was in a high level, while LDH was low. Aerobicmetabolism was in a higher level, providing more energy for a continuous motion ofcrab The results revealed that light color affected respiratory metabolism, and the crabat yellow had higher metabolism while in a less acute environment. So yellow maybethe better illumination condition of the crab culture industry. 3Effects of light on the growth of swimming crab（Portunustrituberculatus）3.1Effects of light intensity on the growth of swimming crab（Portunus trituberculatus）Five light intensity treatment were used to investigate the influence of light onthe growth and respiratory of swimming crab（Portunus trituberculatus）. The resultswere summarized as follows:1.The SGR under different light intensity weresignificantly different (P<0.05). The maximal SGR of crab occurred under800lx.SGR under800lx between0lx and3500lx were significantly different (P<0.05).2.With the increase of the light intensity, the feed FI reduced firstly, then rise. Theminimal FI of crab occurred under800lx.3. The800lx group had maximal FCE, andwas significantly bigger than the others except1500lx group（P<0.05）. Therefore, thecrab may grow better under15μmol·m-2·s-1. The result indicated that light intensitycould influence the growth of the crab. Under800lx,the crab had a highest FCE,though a low food intake. In conclude, the crab may grow better.3.2Effects of light color on the growth of swimming crab（Portunus trituberculatus）Growth performance and energy budget of swimming crab （Portunustrituberculatus）were investigated to study the effect under five light colors. Theresults were summarized as follows:1.The specific growth rates (SGR) underdifferent light intensity were significantly different (P<0.05). The maximal SGR ofcrab occurred under yellow light. SGR under yellow was significantly different fromwhite and bule(P<0.05).2. At bule light, the feed intake (FI) was highest indicatingactive feeding behavior.3.The maximal food conversion efficiency (FCE) occurred inthe yellow group, and significantly higher than the others（P<0.05）.4. Underdifferent light color, energy allocation was different. At yellow light, crab has moreenergy allocation to growth and less energy allocation to respire. Under yellow light,Portunus trituberculatus had a higher FCEdeven if a lower FIdand more energy allocation to growth, and therefore, a higher SGRd. The blue group was active infeeding, with a higher FIdand a lower FCEd, and therefore, a lower SGRd. Inconclusion, the crab may grow better under yellow light.