Studies On The Growth Rate And Absorption Rate Of Nitrogen And Phosphorus Of Three Species Of Eucheuma

Eucheuma is a group of red seaweeds representing the subfamily. Eucheuma toid used in the production of carrageenan, an important product used in cosmetics, food processing,and industrial uses, as well as a food source for those living in China. Betaphycus gelatinum, Kappaphycus striatum or Kappaphycus alvarezii is the particular species cultivated in China known as guso. Some of the most significant species include Betaphycus gelatinae, Eucheuma denticulatum, and several species of the genus Kappaphycus including K alvarezii. Since the mid-1970s, Kappaphycus and Eucheuma have been the major source for the expansion of the carrageenan industry. The farming of Eucheuma has raised certain environmental issues, mostly centered on the ecology and biodiversity of coastal environments.However, the large seaweed has an excellent ability of water quality restoration, and the unicorn culture is developing to a new breeding mode. In this study, the absorption rates of nitrogen and phosphorus in sea water were carried out in the three kinds of eucheuma, and the growth rate of raft and deep sea cage raft model were conducted. Hence,the main research results are as follows:(1) The experimental results of inorganic nitrogen and phosphate uptake rate:According to the regression analysis,Total dissolved inorganic nitrogen (DIN) in seawater and inorganic phosphate (PO4-P) concentration statistically significantly affected the absorption efficiency of three kinds of Eucheuma, which were positively related, but not a linear growth. The single factor variance analysis showed that the absorption rates of the three kind of algae species under different DIN conditions were different in differ degree. When the DIN up to 1.2 mg/L, the difference was the most significantly of statistics while it even behaved the same when the PO4-P concentration was higher than 0.056 mg/L.In the same conditions, Kappaphycus striatum had the highest absorption speed while Kappaphycus alvarezii was the lowest. The uptake inorganic nitrogen ratio was the highest in K. Striatum, while the lowest in K alvarezii, with the highest absorption rates : 8.94 umol / g.h, 6.47 umol / g.h, 5.61umol / g.h., respectively.Three kinds of Eucheuma on DIN uptake rate and the concentration of DIN formula respectively:B.gelatinum DIN absorption rate=1.3909×X0 7499(R2=0.9815),K striatum DIN absorption rate=1.6854×X0.8122(R2=0.9903),K alvarezii DIN absorption rate=1.0338×X0.8302(R2=0.9989).In general, the PO4-P absorption rate of Kappaphycus striatum was the fastest, while most slow in Kappaphycus alvarezii. When the concentration is about 0.016mg/L,Betaphycus gelatinum was the fastest. The highest absorption rates of PO4-P were respectively 0.0875 umol/g.h, 0.0790 umol/g.h, 0.0687 umol/g.h for B.gelatinum, K striatum and K alvarezii.Three kinds of Eucheuma on inorganic PO4-P absorption rate of PO4-P and water salt concentration formula respectively:B. gelatinum PO4-P absorption speed=-0.0012x2+0.0181x+0.0085(R2=0.9639),K. striatum PO4-P absorption speed ?-0.0016x2+0.0237x+0.0008(R2=0.9334),K. alvarezii PO4-P absorption speed =-0.0011x2+0.016x+0.0077(R2=0.9639).(2) According to the estimation of seaweed absorption rate concentration, 100 tons of Kappaphycus striatum in Lingshui Port, the maximum absorption of DIN and PO4-P is 2670 kg and 6110 kg respectively. Moreover, K. striatum (100 tons) can absorb about 2020 kg DIP in Sanya deep sea cage raft aquaculture, and it was 2640 kg for Betaphycus gelatinum in DIP absorption, also by 100 tons.(3) Experimental results of culture:The results of regression analysis showed that the temperature of aquaculture water in the two regions and aquaculture species had no significant effect on the growth rate of Eucheuma; according to single factor analysis of variance: There was no significant difference in the growth rate between Betaphycus gelatinum and Kappaphycus striatum,but they both had a significant difference with Kappaphycus alvarezii.In Lingshui,the Daily growth rate of Betaphycus gelatinum, Kappaphycus striatum and Kappaphycus alvarezii are : 2.82%, 3.54%, 7.76%;In Sanya,the Daily growth rate of B.gelatinum, K striatum and K. alvarezii are : 3.47%, 4.73%, 10.53%.The fastest growth speed of the three algae was K alvarezii between the two regions, about twice as large as that of K.striatum and three times of B. gelatinum,so recommended farming. The growth rate of the two regions aquaculture model was lower than the cement frame mesh culture model in this project,so it is not recommended to use the above method for production and breeding.