| Variation and assessment in sedimental factors and biological mend by bio-degrading bacteria, EUEO-TOWN and sea cucumber in shrimp polyculture enclosure were studied.The main results were: 1 .Variety of sediment in shrimp mariculture ecosystem1.1 Variation of routine factors in sediment of shrimp culture enclourseAmong routine .factors in mariculture sediment, phosphate is a gradual coursing of accumulation and nitrogen is a rapid coursing of accumulation, which can both be used as indicators of organic pollution ; sulfid concentration varies between 0.01-5.44ug/g,EH shows a significantly decreasing tendency during the aquoilture period.both of which can be regarded as sensible parameters of sediments quality;variation of total organic carbon is not regular and C/N is decreasing obviously; the relative indexs of three contamination factors N, Sx P are arraged as: P>S>N in earlier stage of shrimp culture, P>N>S in Iater01.2 Alkaline phosphatase activity in mariculture sedimentAPA is increasing with the course of mariculture; total phosphorus, total nitrogen and total organic carbon had significant effects on APA, in which total nitrogen is negative with APA(r=-0.513) while total phosphorus and total organic carbon positive with APA (rip=0.752, rroc^O.SOl ). In addition, inorganic phosphorus and organic phosphorus are not correlated with APA. This study found that APA could be used as a sensitive indicator of ecological stability and indication of organic pollution in mariculture sediments. 2.Biological mend of sediment in shrimp culture ecosystem2.1 Biological mend of sediment by sea cucumber in shrimp enclosureThe shrimp yield in shrimp-trepang polyculture enclosures is over the control, about 7.69% higher, and the survial of shrimp is 1.48 time as the control; the cultured trepang in treatment has a survial ratio of 50 ?%, and grows 49.63% weighter than before. It can draw a conclusion that shrimp-trepang polyculture is a traditional effective way to optimalize the sediment in shrimp pond.2.2 Organic loading assessment of mariculture sediment in shrimp-oyster polycultureThe concentrations of N, S, P are increasing obviously. The organic pollution in the enclosures with differ oyster-density were different and a valley image of relative index of three multiple contamination factors N, S, P were observed: VI(126.85)>II (98.14) >III (60.64) > IV (33.05) > V (29.68). The treatment V located in the lowest point stand for the optimum density of oyster, which was 1003.2g/m3 or 668.79kg/ mu in production-scale in a density of 60 prawns/m2 pond.2.3 Bio-remediation with bio-degrading bacteriaWith the supplement of bio-degrading bacteria SPM2, SPW3 , 3041 and BIO ENERGIZER, The shrimp yield and survival are not higher than the control, 21.80% and 19.69% lower than the control in shrimp yield; 17.63% and 4.92% in survival. In sedimental quality amending, total organic carbon is degrading obviously in treatment and the effect on phosphate indicated in the earlier stage; however, the degrading effect on nitrogen is not showing apparently and the supplied bacteria have no significant competition to environmental native bacteria.2.4 Bio-remediation with a commercial bacterial supplement EUEO-TOWNThe addition of EUEO-TOWN shows no improvement either in shrimp yield or in sedimentquality over the untreated enclosures. However, the shrimp yield in enclosures with EUEO-TOWN is 40.75% lower than the control, and the survial of shrimp is 13.57% lower than the control; the supplement of EUEO-TOWN in treatment can also not decrease the concentration of nitrogen , phosphate and sulphur, but especially increase the concentration of the later two factors. |
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