Study On The Carbon Fixation Function Of Seagrasses In The Coastal Area Of Shandong Peninsula

In the present study，we carry out the basic research of the seasonal variations ofmorphology and growth of eelgrass in Swan Lake. The photosynthesis and respirationof eelgrass to environmental factors (salinity, temperature, illumination, copper ionand sulfur) response were investigated. We compare the decomposition speed ofeelgrass of different organization in different seasons and the effect of differentmaterials, different environment and different screen on the decomposition speed ofeelgrass. The findings of the research can indicate the role of eelgrass in ShandongPeninsula in the carbon cycle and provide basic data for seagrass morphologicalcharacteristics and ecological studies. The main results are summarized as follows:1. From August in2012to July in2013, the surface water temperature and themorphological characteristics, plant density, biomass and primary productivity ofeelgrass in Swan Lake were monitored monthly. The results indicated that themorphological characteristics, plant density, biomass and primary productivity ofeelgrass showed obvious seasonal variations. Eelgrass grew slowly and was small inwinter as a result of low temperature, and the growth accelerated with temperaturerising in spring. Optimal water temperature for eelgrass growth was achieved in earlysummer, as a result, the biomass and productivity reached maximum. While thebiomass, shoot density and productivity of eelgrass began to decrease in late summerbecause of exorbitant water temperature. These seasonal variations were stronglycorrelated with seasonally varied water temperature.2. The impact of salinity, temperature, illumination, copper ion and sulfide on thephotosynthesis and respiration of eelgrass were carried out indoors from March toApril in2013. The results indicated that eelgrass is a euryhaline plant, and the photosynthetic rate was highest when the salinity was between31and40. What’smore, the tolerance of eelgrass to high salinity is higher than that to low salinity. Thephotosynthetic rate was highest at the temperature of15℃. The light compensationpoint was11.59umolm-2s-1at the temperature of17.3℃. High concentration of copperion concentration (more than1mgL-1) and sulfide (0.8mmolL-1) would cause thephotosynthetic rate dropped significantly.3. The decomposition speed of eelgrass was studied in Olympic sailing base inQingdao and Swan Lake in Rongcheng from September in2012to November in2013.According to the results, the decomposition speed was fastest in the summer, and wslowest in winter. The decomposition speed of older leaf and rhizome were slowerthan the younger. The decomposition speed of eelgrass was related with the exposurein the waves and currents. The greater the degree of exposure of the waves andcurrents, the faster the degradation speed. Eelgrass degradation process need befurther researched.