| The clams Ruditapes philippinarum are important economy shellfishaquaculture objects in our country, especially in the north of Shandong andLiaoning area, which bring out good economic and social benefits. But highdensity culture destroy shellfish survival environment and lead to eutrophication ofaquaculture water. And a series of ecological problems caused by them hasbecome an important factor restricting the economic development. The purpose inthe study is to research the effects of hypoxic stress on the metabolic profile of theRuditapes philippinarum, organizational structure, oxygen consumption andammonia excretion rate, CO2production and O: N ratio. The main results are asfollows:1. Hypoxic stress on the influence of the metabolic profile of RuditapesphilippinarumThe nuclear magnetic resonance(NMR)spectroscopy method is employed todiscusses the composition of metabolites under hypoxic conditions. Theseparation on the second,5th,10th and20th day was all attributed to the declinedisoleucine, alanine, succinate, betaine and taurine, and the glycine level wasdecreased on the second,5th and10th day post hypoxia challenge. The tyrosineand phenylalanine levels were elevated in the gill tissues on the second day post hypoxia treatment. As time progressed, the levels of tyrosine and phenylalaninedecreased gradually to recover the blank level, and the arginine level was declinedon the fifth day after hypoxia challenge. The phenylalanine and aspartate level wasincreased on10th and20th day respectively, and turned to be significantmetabolites to discriminate the blank and hypoxia-challenge groups.2. The influence of the hypoxia stress physiological metabolism of RuditapesphilippinarumIn order to detect the pathologic changes of organization in Ruditapesphilippinarum, the hematoxylin-eosin stain (H-E) method was employed after20days of exploring to hypoxia (DO <2mg·L-1) stress. Oxygen consumption,ammonia excretion rate, CO2production and O: N ratio was also measured inRuditapes philippinarum exposure to hypoxia (DO <2mg·L-1) on the2nd,5th,10th and20th day. The results showed that visible structural difference wasobserved between the clams challenged by hypoxia and control groups. And therewere deep purple round spots scattered distribution of individual tissue in thehypoxia group, which might be due to abnormal lipid metabolism to form the lipidaccumulation in the clams challenged by hypoxia.In22℃watertemperature, oxygen consumption, ammonia excretion rate and CO2production ofclams were significantly affected by hypoxia stress. The oxygen consumption,ammonia excretion rate and CO2production of the clam decreased when exposureto hypoxia on the2nd day, which were reached0.5665mg·g-1·h-1,0.0794mg·g-1·h-1and26.2364mg·g-1·h-1respectively. Oxygen consumption and ammoniaexcretion rate reached the lowest level on the2nd day. But CO2production on the20th day reached the lowest value (7.4220mg·g-1·h-1), which was about one halfcompared to the control group. The O:N ratio range was6.25-12.11in the hypoxiagroup, which reached to maximum value12.11in the clams exposure to hypoxia stress on the20th day. Therefore, hypoxia challenge had an important impact onthe organizational structure and physiological metabolism (oxygen consumption,ammonia excretion rate, CO2production and O:N ratio) in clams. The aboveresults could provide some theoretical basis for the scientific managementof the clams breeding and administration. |
