The Research About Application Technology Of Food Organism In Scylla Paramamosain Seed Production In Ponds

The article regarded Scylla paramamosain seeds production asresearch object. The research methods combined laboratory researchmethods and production experiment methods. We studied suitable densityof preying on copepods about Scylla paramamosain zoaea in differentdevelopment stages. What’s more, we studied control and application ofcopepods in Scylla paramamosain seeds production in ponds. Finally, westudied changing water quality and density of live food in the process ofScylla paramamosain seeds production in ponds. We hoped that using themode of seeds production in ponds,which used rotifers and copepods,replaced the mode of seeds production in factory, which used rotifers andArtemia nauplius, in order to achieve goals of saving cost in Scyllaparamamosain seeds production.1. The utilization of Oithona brevicornis in Scylla paramamosain seedsproductionThe experiment studied the function of Oithona brevicornis in Scyllaparamamosain seeds production, aiming at using Oithona brevicornis to replace Artemia nauplius in order to solve the problem that rising price ofArtemia eggs led to high cost of Scylla paramamosain seeds production.Research results indicated that Scylla paramamosain’s zoeae were able tocatch and feed on Oithona brevicornis in and after the stage of Z3, andlarvae had the better metamorphosis survival rates when Oithonabrevicornis were in suitable density and size. When young Oithonabrevicornis which were filtered by80mesh sieve and collected by100meshsieve reached to3ind/ml, the metamorphosis survival rate from Z3(ZoeaⅢ) to Z4was48.89%. It had not significantly different with themetamorphosis survival rate of Z3about control group of Artemia nauplius（P>0.05）, while the metamorphosis survival rates of Z3about the groupsof adult Oithona brevicornis under different densities in experimentaldesign were all significantly different and low to the metamorphosissurvival rate of Z3about control group of Artemia naupliu（sP<0.05）. Whenthe density of adult Oithona brevicornis reached to5ind/ml, themetamorphosis survival rates about Z4and Z5are73.33%and47.78%,respectively. They were not all significantly different with themetamorphosis survival rates of the same stage about control group ofArtemia nauplius（67.78%and43.34%, respectively）. Results above showthat the young Oithona brevicornis can replace Artemia nauplius to belarvae’s food in the stage of Z3. We can directly use the adult Oithona brevicornis to feed larvae in and after the stage of Z4. The metamorphosissurvival rates about Scylla paramamosain’s later zoeae (from Z4to M)which feed on young Oithona brevicornis can be improved by way ofsuitably increasing the density of food.2. The impact of Oithona brevicornis in Scylla paramamosain seedsproduction in ponds in the early stageThe article studied the impact of Oithona brevicornis to rotifer andZ1in Scylla paramamosain seeds production in pond in the early stage,aiming at reasonably controlling or using Oithona brevicornis.Experimental results indicated that when the density of adult or youngOithona brevicornis was at or beyond333ind/L, they both had significantimpact on the survival of rotifer comparing with blank group, and survivalrates of rotifer were gradually declining with increasing density of copepod.When the density of adult or young Oithona brevicornis was at or beyond556ind/L, they both had significant impact on the metamorphosis survivalrates of Z1comparing with blank group. Research results above show thatwe must strictly handle rotifers which are used to feed zoeae, in caseOithona brevicornis consisted in rotifer have bad impact on Scyllaparamamosain seeds production in pond in the early stage.3. Scylla paramamosain seeds production in pondsThe article studied water quality indexes including pH, COD, Ammonia Nitrogen and Nitrite Nitrogen, and biological indicatorsincluding the density of rotifers and copepods. Research results showedthat the value of pH is gradually declining with seeds production going onand average value is8.07. The value of COD is gradually increasing fromthe early stage to the later stage of seeds production and average value is4.7273mg O2/L. The value of Ammonia Nitrogen is0.01712mg/L. Thevalue of Nitrite Nitrogen is gradually increasing and average value is0.00023mg/L. The density of rotifers ranged from0.3ind/ml to10.3ind/ml,and average value is4.04ind/ml. The density of copepods ranged from0.2ind/ml to2.7ind/ml, and average value is1.25ind/ml. In the period ofScylla paramamosain seeds production, we used rotifers to feed the larvaein the stage of Z1and Z2, and used young Oithona brevicornis to feed thelarvae in the stage of Z3, and used adult Oithona brevicornis to feed thelarvae in the stage of Z4and Z5. The densities of copepods were kept about5000ind/L through supplementing copepods. The result was that survivalrate from Z1to M was13.3%, and the cost of seeds production was32percents less than seeds production in factory.