Photosynthetic Carbon Acquisition And Diet Contribution To Abalone, And Sea Cucumber In Macroalgae

Macroalgae,the key primary producer in marine ecosysterm, carbon fixed result inphotosynthesis while release oxygen and absorb nutrient in seawater, as an importantpart of the energy and material enter marine ecosystem which connect the carbon andnitrogen biogenic elements cycle. As a precondition to understand the cycle of thecarbon and nitrogen biogenic elements in marine ecosystem to build high-yield bottonsowing Seafood-abalone and sea cucumber farming model, aim to achieve a rationalallocation of aquaculture space and resources.This paper can be divied into three parts to sudy on the macroalgae photosynthesiscarbon fix and diet contribution to abalone Haliotis discus hannai and sea cucumberApostichopus japonicus（Selenka）（Echinodermata: Holothuroidea）. The fist aspect isthe distuibution of spatial diversity of benthic macroalgae community in botton sawingareae. The second aspect is the effect on uptake inorganic carbon of difference phylumin sea water. The third aspect is the macroalgae food contribution to the bottom sowingabalone Haliotis discus hannai and sea cucumber Apostichopus japonicus.The purposeof this study is investigate the environmental conditions of botton sowing areas inLaoshan Bay, to explore the species and distribution of the benthic macroalgaecommunity. Research object foucus on the typical bottom sowing Multi TrophicAquaculture （IMTA） system, combined carbon and nitrogen stable isotope to caculatethe food contribution of macroalgae to the abalone and Apostichopus japonicus, toexplain the transform and trasport of carbon and nitrogen biogenic elements in bottonsowing IMTA system,to provide a basis for better botttom sowing IMTA aquaculturemodel. Results as follows:1) Investigated the distribution of spatial diversity of benthic macroalgae communityin botton sawing areas in the spring and autumn in2012; compared the benthicmacroalgae community of Diaolong Zui, Yang Kou, Feng Shan, Gang Dong; analyzedthe structure of the benthic macroalgae community; The survey results show that theMargalef species richness index, Shannon-Wien especies diversity index and Pielou evenness index were no significant difference. In spring the richness: Feng Shan, GangDong, Yang Kou, Diaolong Zui while in autumn the richness: Diaolong Zui, Yang Kou,Feng Shan, Gang Dong. In spring Undaria pinnatifida is the key specie of the benthicmacroalgae community; in autumn Plocamium telfairiae is the key specie of the benthicmacroalgae community.2) Iodimetry measurement for dissolved oxygen and Total alkalinity （TA）calculation determination for dissolved inorganic carbon （DIC） are taken to measurerate of O2evolution and DIC acquisition in sealed synthetic glass containers，respectively. Introduction of Total alkalinity （TA） calculation can be determination forDIC. Macroalgae can significantly change the DIC concentration of the sea water, onsite add nutreint or CO₂impact on the carbon fix not the same. In low nutrient level,add nutrient can remarkable enhance the O2evolution rate （RO）; however add nutrientmay have no significant effect on both DIC and the composition of DIC uptake rate.Add CO₂have significante effect on DIC fix rate.No add CO₂,DIC uptake rate ofSargassum thunbergii is （maximum423.36μmol/gDW·h） higher than Ulva lactuca andSargassum muticum;CO₂uptake rate of Ulva lactuca is （maximum12.34μmol/gDW·h）higher than Sargassum thunbergii and Sargassum muticum; HCO₃^-uptake rate ofSargassum thunbergii is （maximum572.34μmol/gDW·h） higher than Ulvalactuca,Sargassum muticum.Add CO₂,DIC uptake rate of Ulva lactuca is （maximum777.19μmol/gDW·h） higher than Sargassum thunbergii and Sargassum muticum;CO₂uptake rate of Ulva lactuca is （maximum64.84μmol/gDW·h） higher than Sargassumthunbergii and Sargassum muticum; HCO₃^-uptake rate of Ulva lactuca is （maximum966.64μmol/gDW·h） higher than Sargassum thunbergii,Sargassum muticum.Photosynthetic Quotient （PQ） in this study is range from0.36to1.18.3) Macroalgae is one of the important food sources for consumer in the food web.Fix carbon through photosynthesis and uptake nutrient then transmit energy andmaterial to next trophic. Macroalgae has its own DIC uptake mechanism lead to uniqueδ¹³C value. Through carbon and nitrogen stable isotope, measure the contribution ofMacroalgae to the abalone and sea cucumber Apostichopus japonicus in spring andautumn. The macroalgae community seasonal changes effect on the consumer, the δ¹³Cvalue of macroalgae:（-34.6^-12.3）‰; δ¹⁵N value of macroalgae（4.9⁹.5）‰.Dictyopteris undulata is improtant for abalone in the spring, so do the Phaeophyta to the Apostichopus japonicus; Ulva lactuca is improtant for abalone in the autumn, so dothe Chlorophyta to the Apostichopus japonicus.