The Research On Polyculture Model Of Abalone And Seaweed

Abalone aquaculture developed rapidly in our country, and the farming scale and densityContinuous increasing. With the expansion of the farming scale, the self-pollution of abaloneworrying, new ideas and methods must be adopted to solve those problems. Focusing on thecriterion above, we set up the polyculture experiment of abalone and seaweeds, aimed at usingthe purification effect of algae to solve the the problem of the self-pollution of abalone. Theexperiment can be divided into three parts.,the main details are as follows:1. The polyculture experiment of hybridized abalone and four kinds of seaweeds(Enteromorpha prolifra、Ulva lactuca、Gracilaria chorda、Gracilaria asiatica)was took in algaecultivating pool witch the scale was180cm×150cm×130cm.and we determine the nutrientcontent, temperature, illumination and other physical and chemical factors in the pool on aregular basis. The results showed that in the condition of polyculture, four kinds of algae canpurify the nutrients of aquaculture ponds effectively. Among them The absorption rate ofE.prolifra on NH4+-N，NO3--N，NO2--N and PO43--P are85%,71%,72%and85%respectively;and the U.lactuca’s absorption rate on those four kinds of nutrient were96%,76%,68%and88%respectively; and the absorption rate of the G.asiatica on four kinds of nutrients were90%,80%,82%and90%respectively; to the G.chorda the absorption rate were91%,86%,82%,91%respectively. From the perspective of ammonia nitrogen removal ability, the four kinds ofseaweeds listed in order of purifying effect: U.lactuca> G.asiatica> G.chorda> E.prolifra; fromthe perspective of inorganic phosphorus absorption effect, four kinds of algae removal ability inturn was: G.asiatica> G.chorda> U.lactuca> E.prolifra. In addition, when other conditions werein similar circumstances, the growth rate of hybridized abalone under polyculture was higherthan the single plate. the specific growth rate of abalone weight in control was23%, thespecific growth rate of E.prolifra was35%, the U.lactuca was55%, the G.chorda was40%, andthe G.asiatica was51%. when mixed culture, the growth effects of hybridized abalone in turnwas: U.lactuca> G.asiatica> G.chorda> E.prolifra. The survival rate between polyculture andsingle plate did not appear to be much different.Synthesis the effect of water quality purificationof four kinds of algae and their impact on the growth rate of hybridized abalone, U.lactuca andG.asiatica have better effect when they were mixed culture with hybridized abalone.2. In this experiment, we cultivate U.lactuca and G.asiatica in glass tanks (34cm×24.5cm ×22.5cm) respectively of different density. The density level of U.lactuca was:1g/L,2g/L,3g/L,4g/L; and to the G.asiatica was3g/L,4.5g/L,6g/L,7.5g/L.They were putted in nutritivesalt water for24h and the content of nutrients were determined every2h. The result showed that:all levels of algae can absorb the Nitrogen and Phosphorus nutrient in water effectively, and thehigher density of algae, the more obvious effect. With the consideration for practical application,we thought the density of3g/L U.lactuca and6g/L G.asiatica the most suitable concentrationwhen other conditions were similar. After24h, the absorption rate of NH4+-N, NO3--N，NO-2-N,PO43--P of3g/L U.lactuca were60.2%,58.6%,56.5%,55.1%respectively. In6g/L G.asiaticathe four kinds of nutrients’ absorption rate were:46.6%,45.7%,48.4%,41.6%respectively.Among the four kinds of nutrients, both U.lactuca and G.asiatica have higher removal rate ofammonia nitrogen, the3g/L U.lactuca’s purification rate could reach60.2%. Compared withother nutrients, the removal rate of phosphate was not high of those two kinds of algae, it were55.1%and41.6%, respectively.3. In this experiment,in order to get the best density of hybridized abalone when mixedculture with3g/L U.lactuca and6g/L G.asiatica,we set the hybridized abalone on three densitylevel:200/pool、400/pool、600/pool.All the experiment group were set in seaweed cultivationpool respectively. The results showed that: when mixed culture with U.lactuca, the growth ratesof hybridized abalone on three density were84%、62.6%、31.4%respectively; and when mixedculture with G.asiatica the growth rate were71.4%,52.29%,30.3%respectively. When thealgae density was fixed, the density of abalone increased, the growth rate of hybridized abalonefall. When the density of abalone was400/pool,the growth rate of abalone both upon50%,which was lower then the group of200/pool21.4%and19.11%, and higher then the groupof600/pool31.2%,21.99%. so when mixed culture with3g/L U.lactuca and6g/L G.asiaticathe density of400/pool of hybridized abalone is more appropriate. In addition, the experimentalresults also showed that under the condition of the equivalent density of the hybridized abalone,U.lactuca purification effect is better than that of G.asiatica, and also has great influence on thegrowth of abalone.