| In this article, research on aestivation of Apostichopus japonicus Selenka wasreviewed, including the time period, threshold temperature and incentives foraestivation, and major physiological change of the animal during aestivation．Thetheoretical basis and possibility for aestivation“alleviationâ€or reduction via control ofenvironmental conditions were also discussed．With existing data and cases of the seacucumber industrialized cultivation, management measures for industrialized seacucumber cultivation were developed, including temperature, light, water qualitycontrol and nutrition manipulation. Furthermore, the key technical problem and futureresearch on industrialized sea cucumber farming were suggested．On this basis, theexperiments of the temperature control in dormancy were performed to providetheoretical support for solving the key technical in sea cucumber culture. The mainresults are as followings:1. Effect of different temperature regime on growth and body wall composition ofA．japonicus in aestivationTo investigate the effect of low temperature treatment on growth and body wallcomposition of A. japonicus during aestivation, three groups of sea cucumbers (averagebody weight65.26±4.37g) were cultured for120d at different temperature regimes.Treatment A was cultured at low temperatures indoor throughout the experiment, whileTreatments B and C were cultured at low temperatures indoor after aestivation for30dand60d, respectively. The sea cucumbers were sampled every30days during theexperiment, and their growth and body wall composition were analyzed. It was foundthat the weight of sea cucumbers decreased significantly during aestivation, butincreased rapidly and significantly after aestivation. Low temperature treatmentprevents most of the sea cucumbers from aestivating, yet their growth were not as good as the sea cucumbers in other treatments. The specific growth rate of Treatments A, Band C were0.03%/d,0.27%/d and0.32%/d, respectively, however, their survival ratewere91.67%,71.43%and53.57%, respectively. Although culturing at low temperaturesduring aestivation did not promote growth of the animals, it may contribute to highersurvivorship. Ranking from high to low percentage, the nutritional components of seacucumber body wall are moisture, crude protein, ash, total sugar, and crude lipids. Afterbeing cultured for30d, Treatments B and C showed higher contents of crude proteinand crude lipids, but less moisture, ash and total sugar, compared to Treatment A. By theend of the experiment, Treatments A and C showed no significant difference (P>0.05) inbody wall composition compared to their initial values; this was also found in TreatmentB except that its content of crude lipids was significantly lower (P <0.05) than the initialvalue. The results indicated that some sea cucumbers may still aestivate under lowtemperature treatment in summer; sea cucumbers generally show a rapid weightincrease after aestivation, and this weight increase did not accompany with significantchange of body wall composition except for crude lipids.2. Effect of different temperature regime on growth and body wall composition ofA．japonicus in hibernationTo investigate the effects of different rearing conditions on growth and body wallcomposition of the sea cucumber A．japonicus in hibernation, three groups of seacucumbers (average weight35.48±5.84g) have been fed for150days in differentrearing conditions (Treatments A and B were cultured indoor at high temperature afterhibernating at natural temperatures for60days or30days, respectively; Treatment Cwas cultured indoor at high temperature). The growth of sea cucumbers and the changein their body wall composition were analyzed. The specific growth rate of Treatments A,B and C were0.19%d-1,0.28%d-1and0.34%d-1, respectively; the survival rate were82.22%,88.15%and92.59%respectively. Results showed that, the weight of seacucumber decreased significantly during hibernation, while feeding sea cucumbers athigh temperature in winter could benefit both their growth and survival. Afterhibernation, from late March to late April, sea cucumbers enter into rapid growth stage.The nutrition contents of sea cucumber body wall, ranking from high to low are:moisture, crude protein, ash, total sugar and crude fat. After being fed for30days, thecontents of crude protein, crude fat, and ash of the still water treatments were more and moisture were less than the flowing water treatment, respectively, and the total sugarcontent changes irregularly. There was no significant difference (P>0.05) between theoriginal and final body wall composition of Treatments A and C. No significant change(P <0.05) was found in most of the body wall nutrition contents of Treatment B, exceptthat the moisture content showed significant decrease（P<0.05）and the sugar contentshowed significant increase (P<0.05). In conclusion, artificially increase watertemperature in winter may improve sea cucumber growth and prevent hibernation,without any negative impact on sea cucumber nutrition and quality except for moisture andtotal sugar.In this study, the advantage of sea cucumber indoor industrialized cultivation wasdetermined by comparative study of temperature control during summer and winter foralleviating aestivation and hibernation. Compared to traditional outdoor cultivation,such as pond culture and shallow seabed sowing, environmental conditions ofindustrialized facilities are under better control, so that the sea cucumbers showedgreater growth rate and survivorship. Evidence in growth rate and body wallcomposition of A．japonicus confirmed that temperature-control had a positive impacton manipulating dormancy of sea cucumber. This study aims to provide theoretical basisfor optimizing the technology and recommending for future development of seacucumber indoor industrialized cultivation. |
