Study On Physiological Energetics In Urechis Uniconctus

The Urechis unicinctus is a valuable seafood product with high economic value.With the continuous research,its medicinal value is also constantly displayed.The Urechis unicinctus also has an indispensable position in ecology.To explore the energy distribution of Urechis unicinctus and its role in the water ecosystem,the physiological energetics of Urechis unicinctus was studied.From the perspective of ecophysiology,the effects of temperature and body weight on the physiological activities of Urechis unicinctus were studied from Otc.2016 to Mar.2017.The basic metabolism which were fed with Spirulina were studied at 10?,12?,16?,20?,24?,27 and 30? ?.And on the basis of this,energy budget,carbon and nitrogen budget of Urechis unicinctus were studied at their optimum temperature.And established the energy budget equation under different temperatures.The experimental results are as follows:(1)Effects of temperature and body weight on the oxygen consumption and ammonia excretion of Urechis unicinctus.In this experiment,the oxygen consumption rate increased with the increase of temperature in the range of 10 ~ 24 ?,and the oxygen consumption rate reached the maximum at 24 ?.When the temperature continues to rise,the oxygen consumption rate and the temperature was negatively correlated.The Q10 value was greater than 1 in the range of 12~24 ° C and was 1.9102-11.8594.The Q10 value was less than 1 at 10~12 ° C and 24~30 ° C,indicating that both low and high temperature had different effects on the growth of Urechis unicinctus.With the increase of temperature,the rate of ammonia excretion continued to increase.The relationship between body weight and oxygen consumption rate and ammonia excretion rate of Urechis unicinctus can be expressed as negative power function R = a Wb-1.Throughout the experiment,O:N ratio between 3.2128~12.9672,indicating that with the temperature changes,Urechis unicinctus metabolic substrates also have significant changes.(2)The diurnal variation of metabolism of Urechis unicinctus.Experiments show that diurnal variation of routine metabolism of Urechis unicinctus were relatively significant compared with standard metabolism.Only one peak of oxygen consumption rate and ammonia excretion rate appeared in the experiment in one day-night.Oxygen consumption rate of SDA appeared after feeding 6h-18 h,with an average duration of 9~12h.Routine metabolism of Urechis unicinctus is a high level at nighttime(0: 00~6: 00)and may be related to its nocturnal living habits.(3)Research on energy budget.At 16 ?~ 24 ?,the feeding rate increased with the increase of temperature,the highest at 24 ?,the maximum growth rate appeared at20 ?.Among the components of the energy budget,the proportion of excretion can be the lowest,respiratory energy accounted for the largest,excretion and growth energy is not much difference.The energy balance equation for Urechis unicinctus at different temperatures is as follows: 16?:100C=52.80R+2.95U+21.71F+22.54 P 20?:100C=49.72R+3.79U+23.32F+23.17 P 24?:100C=51.48R+5.47U+19.50F+23.55P(4)Research on carbon budget.In this experiment,the average carbon absorption efficiency of Urechis unicinctus at 16 ?,20 and 24 were 74.63%,78.6% and ? ?76.67%,respectively,and the gross growth rate was 21.07%,26.03% and 22.37%,which all have a maximum at 20 °C.And at the same temperature,the absorption efficiency of Urechis unicinctus decreased with the increase of body weight.The minimum carbon requirement is maximum at 16 °C due to the lower temperatures,which require more carbon to sustain its own metabolism.While more carbon was used for growth at 20 °C and 24 °C.Respiration and excretion accounted for the largest proportion of carbon consumption,ranging from 48.36 to 58.28%.(5)Research on nitrogen budget.At 16 ?~ 24?,temperature and body weight had significant effects on nitrogen intake,assimilation efficiency and accumulation efficiency.The dry weight and nitrogen ingestion rates can be expressed as a power function CN = a Wb-1,where a value is highest at 20 °C.In this temperature range,Urechis unicinctus excreted nitrogen accounted for the largest proportion of nitrogen consumption was 55.54 ~ 74.03%.Growth of nitrogen accounted for 16.42 ~ 30.46%,the highest value at 24 ?.