Responses Of The Main Nutrient Components And Physioligical Changes Of Apostichopus Japonicus To The Environmental Variation

As the promotion of people's living standards and health consciousness, the sea cucumber prices continue rising and the demand for sea cucumber is increasing. Sea cucumber artificial cultivation emerges as a result. However, sea cucumber cultivation industry is still in its infancy mainly because little is known about the sea cucumber polyculture although the culture patterns have become diversified. Confirming the main culture species and validity in sea cucumber Polyculture species is an important aspect to increasing the economic and ecological benefits. On the other hand, the water environmental factors play essential role in influencing such physiological activities as ingestion, growth, reproduction and embryo development of sea cucumber. However, the present study in the relationship between the sea cucumber and ecological environment is still at an initial stage, the basic research on sea cucumber was not thorough enough, the impact of environmental factors on the sea cucumber comparative lack of basic information.Two different culture ponds:Rhopilema esculentum Kishinouye and A. japonicus co-culture and A. japonicus Monoculture were chosen to study in Weihai, Shandong Province (122°05'-122°25'N,36°35'-37°E) during Apr.2007-Dec.2008 at spring, summer, autumn and winter respectively. The water environmental factors were investigated and the main nutrient compositions of A. japonicus were analyzed simultaneously. The relationship between the environmental factor variation and nutrient components were also estimated aiming at finding out the key environmental factors. Basing on the above results, one of the key environmental factors:salinity, was chosen to study its effects on physiological status of A. japonicus. Results showed that: Ⅰ.The investigation and identification of the key environmental factors that affecting the main nutrient components of A. japonicus1.The investigation of environmental factors and main nutrient components in two pond (Polyculture and Monoculture) Main water environmental factors:temperature, salinity, dissolved oxygen DO, pH, nitrate, nitrite and ammonium were investigated at four seasons and the main nutrient compositions of A. japonicus were analyzed simultaneously. Except pH, other environmental factors were different at different seasons (P<0.05). When Rhopilema esculentum Kishinouye and A. japonicus were cultured at spring and summer, DO, nitrate, nitrite and ammonium concentrations were quite different in two pond (P <0.05). The main nutrient compositions of A. japonicus were different at different seasons (P<0.05), while the main nutrient compositions were not different.2. Analysis of correlation between environmental factors and nutritional componentsAnalysis of The correlation between environmental factors and nutritional components were analysed by spss software package. Water temperature, salinity, DO, pH and nitrite concentrations had relationship with nutrient components while pH and nitrite only had relation with the total lipid content. and water temperature, salinity, DO presented more significance as compared to other factors. Moreover, temperature had negative correlation with crude protein content, water content, ash content, and had positive correlation with fat and sugar contents.Salinity had negative correlation with fat, sugar, water and ash content, had positive correlation with crude protein. Dissolved oxygen had positive correlation with crude protein content and ash content,had negative correlation with the sugar and water content.Ⅱ. Effect of the key environmental factors:salinity on physiological status of A. japonicus under the conditions of experimental ecology.1.Effect of salinity on ingestion and growth of A. japonicus Under the controlled experimental conditions, effect of salinity(23,26,29,32,35) on feeding and growth of A. japonicus were studied. Ingestion had little difference in the treated groups with salinity changes (P> 0.05). Digestion changed with salinity variations:the digestion rate showed increased firstly and then reduced with salinity increased (P< 0.05). It decreased to the lowest at salinity 23 and reached the maximum at salinity 29. The changing of growth rate presented the similar changing tendency with digestion rate. Results suggested the optimal salinity for growth was 29-30.2.Effect of salinity on digestive enzyme activity of A. japonicus Under the experimental conditions, effect of salinity(23,26,29,32,35) on digestive enzyme activity of A. japonicus were studied. The activities of digestive enzymes(protease,lipase,amylase) changed with salinity variations:the activities showed increased firstly and then reduced with salinity increased (P< 0.05). It decreased to the lowest at salinity 23 and reached the maximum at salinity 29-32.3. Effect of salinity on mechanism of A. japonicus Under the experimental conditions, effect of salinity(23,26,29,32,35) on mechanism of A. japonicus were studied. The mechanism of A. japonicus changed with salinity variations:the oxygen consumption rate and ammonia-N excretion showed increased firstly and then reduced with salinity increased (P< 0.05). They decreased to the lowest at salinity 23 and reached the maximum at salinity 29. The O:N rate were larger than 10, indicating that fat and carbohydrate were used as the metabolism of substrate.