Effects Of Acute Salinity Change On The Growth、Energy Budget And Respiration Metabolism Of The Juvenile Sea Cucumber Apostichopus Japonicus Selenka

The study was designed to determine the effects of acute salinity change onthegrowth, energy budget and respiration metabolismof the juvenile seacucumberApostichopus japonicus. The primary results of these studies are listedbelow.1．Effects of acute salinity change on the growthand biochemical composition of seacucumber Apostichopus japonicusExperiment was conducted to examine the effects of acute salinity change on thegrowth and biochemical composition of sea cucumber Apostichopus japonicus. Thesalinity of the control treatment (S32) was32ppt throughout the experiment,whiletreatments S20、S24、S28and S36were subjected to acute salinity change from32pptto20,24,28,36ppt respectively. After32days feeding trial, the SGR of S20、S24andS36was negative. The SGR of S20and S24was significantly lower than that of S36（p＜0.05）. The SGR of S20was lower than that of S24, and the SGR of S32washigher than that of S28. The feed intakes (FI) was S36＜S20＜S24＜S28＜S32. TheFI of S36was lower significantly than that of the other treatments（p＜0.05）. The FIof S20and S24were lower significantly than S28and S32（p＜0.05）. The feedconversion efficiency(FCE) of S20、S24and S36was negative. The FCE of S36waslower significantly than that S20and S24（p＜0.05）. The FCE of S20was lower thanthat of S24, and the FCE of S32was higher than that of S28. The content of crudeprotein and energy of sea cucumber increasd as the salinity declined, and ash contentincreased as the salinity increased in all treatments. There was no significantdifferences of crude lipid content in all treatments（p＞0.05）. The content of crudeprotein, crude lipid, water and energy of S20were higher significantly than that ofS32and S36（p＜0.05）. 2．Effects of acute salinity change on the energy budget of sea cucumberApostichopusjaponicasExperiment was conducted to examine the effects of acute salinity change on theenergy budget of sea cucumber Apostichopus japonicas. The salinity of the controltreatment (S32) was32ppt throughout the experiment, while treatments S20、S24、S28and S36were subjected to acute salinity change from32ppt to20、24、28、36pptrespectively. The results showed that the SGRe、Ke、K1、K3of S28and S32weredifferent from that of S20、S24、S36significantly（p＜0.05）.The K1of S24and theK3of S36were differently from that of the other treatments significantly（p＜0.05）.The feeding energy, energy lost for feces, energy in excretion and respiration energyof all treatments increased firstly and then declined with the salinity increased. Thegrowth energy of S20、S24and S36were negative. The growth energy of S32washigher than that of S28. Allocation of energy used for respiration was highest（55.75～63.33%）, and then used for feces was higher（33.58～40.04%）. Thepercentage of growth energy of S20、S24and S36were lower than that of S32andS28significantly（p＜0.05）. There were significant differences of energy used forfeeding, growth, feces, excretion, respiration among S32and S20、S36（p＜0.05）.3．Effects of acute salinity change on the osmotic pressure and respiration metabolismof sea cucumber Apostichopus japonicusExperiment was conducted to examine the effects of acute salinity change on therespiration metabolism of sea cucumber Apostichopus japonicas. The salinity of thecontrol treatment (S32) was32ppt throughout the experiment, while treatments S20、S24、S28and S36were subjected to acute salinity change from32ppt to20、24、28、36ppt respectively. The experiment lasted for32d. The results showed that theosmotic pressure of S20、S24、S28declined firstly, and then increased, and declinedagain gradually with the time increment. The osmotic pressure of S36increasedgradually with time lasting. The osmotic pressure of the control treatment fluctuatedwith the time in a small amplitude.The Weight Specific Respiration Rate and theWeight Specific Excretion Rate increased firstly and then declined with the timelasting under different acute salinity change. The O: N ratios were all higher than10 in all treatments, indicating that the sea cucumber in our test conditions utilizedmainly carbonhydrate and lipid as its energy sources.4. Effect of salinity change on the respiratory metabolism of sea cucumberApostichopus japonicusThe respiratory metabolism of intact and eviscerated sea cucumber and theoxygen consumption rate of respiratory tree and body wall in vivo of sea cucumberwere studied. The results reveal that, under the condition of acute salinity change,with salinity increasing, the oxygen consumption rates of intact and eviscerated seacucumber decrease after rising first, rise again, which reach the minimum value undersalinity20; the ammonia excretion rates decline after rising first, rise and thendecrease, which reach the minimum value under salinity32; the oxygen consumptionrate of respiratory tree decreases after rising first, rises and then decreases, whichreaches the minimum value under salinity20; the oxygen consumption rate of bodywall decreases after rising first, rises again, which reaches the minimum value undersalinity20; the ratio of them declines after rising first, rises and then decreases, whichreaches the minimum value under salinity32. The effects of acute salinity change onthe oxygen consumption rates of intact and eviscerated sea cucumber are extremelysignificant (p＜0.01), and that on the oxygen consumption rate of respiratory tree issignificant (p＜0.05). Under the condition of gradual salinity change, with salinityincreasing, the oxygen consumption rates of intact and eviscerated sea cucumberdecline first, and then increase, which reach the minimum value under salinity28; theammonia excretion rates rise after decreasing first, decrease and then rise, whichreach the minimum value under salinity32; the oxygen consumption rate ofrespiratory tree and body wall decreases after rising first, rises again, which reachesthe minimum value under salinity20; the ratio of them rises after declining, declinesagain, which reaches the maximum value under salinity28. The effects of gradualsalinity change on the oxygen consumption rate of intact and eviscerated sea cucumber are significant (p＜0.05).