A Preliminary Study On The Photosynthetic Carbon Fixation Rate Of Kelp And Wakame

In this paper,we selected Laminaria japonica and Undaria pinnatifida as the research object which are China's northern macroalgae dominant species.This study analysed and estimated the efficiency of carbon sequestration of Laminaria japonica and Undaria pinnatifida in seedling stage,larval stage and adult stage three different growth phase.At the same time,we also measured the carbon(C),nitrogen(N),relative growth rate and photosynthetic entropy of Laminaria japonica and Undaria pinnatifida,with a view to more accurate understanding of the efficiency of carbon sequestration of them,so as to estimate the carbon sequestration of large algae Laminaria japonica and Undaria pinnatifida,and to provide the theory for ecological benefits and artificial breeding.In this paper,the main research results are as follows:(1)Through simulation test in lab,the experiment was divided into three stages:seedling(1-10mm),larva(500mm)and adult(1000mm).We set up experimental group(closed culture),the control group(open culture)and the blank group(closed without algae).The contents of temperature,salinity,dissolved oxygen,total organic carbon(TOC),inorganic carbon(TIC),total carbon(TC)and total nitrogen(TN)were measured and the relative growth rate(RGR),dry / wet weight ratio and the carbon and nitrogen analysis were also calculated after weighing,drying,grinding and filtering.The results showed that the photosynthetic carbon sequestration rate of the Undaria pinnatifida were RIC=2.5?g·g-1(FW)·h-1(seedling);RIC=18.6?g·g-1(FW)·h-1(larva);RIC=23.6?g·g-1(FW)·h-1(adult).The Laminaria japonica were RIC=5.2?g·g-1(FW)·h-1(seedling);RIC=12.1?g·g-1(FW)·h-1(larva);RIC=35.5?g·g-1(FW)·h-1(adult).The rate of photosynthetic carbon sequestration in Laminaria japonica and Undaria pinnatifida was significantly different(P<0.05).The relative growth rate of Undaria pinnatifida were 1.4%(larva);2.67%(adult)and the rate of photosynthetic carbon sequestration in Laminaria japonica were2.62%(larva);4.53%(adult).The results showed that there was significant difference in relative growth rate(P <0.05).The content of carbon in the algae at different growth stages is different,and the difference of nitrogen is not significant.(2)The correlation analysis of TOC,TIC and environmental factors showed that temperature,salinity,dissolved oxygen and pH had significant correlations with seawater inorganic carbon and organic carbon in a certain extent.TIC was negativelycorrelated with temperature,and the correlation coefficient was-0.690,which was positively correlated with dissolved oxygen.The correlation coefficient was 0.779,which was negatively correlated with pH,the correlation coefficient was-0.789.Two species of algae in different growth stages of photosynthetic entropy: Laminaria japonica seedling stage 0.89,larvae stage1.14 and adult stage 1.51;Undaria pinnatifida seedling stage 1.14,larvae stage 1.91.and adult stage 1.03.The difference was significant(P < 0.05),which could be used as an auxiliary parameter to measure photosynthetic carbon sequestration capacity.(3)The photosynthetic carbon sequestration rate of algae shows the photosynthetic carbon sequestration efficiency of algae in this situation.According to the analysis of photosynthetic entropy and element analysis of algae,there were significant differences in the photosynthetic carbon sequestration efficiency at the three growth stages with Laminaria japonica and Undaria pinnatifida.Among them,adult algae had the highest carbon fixation efficiency,and the larvae were the second,but they were similar,and the seedlings were the lowest.