Studies On Growth And Biochemical Characteristics Of Halophila Ovalis(R.BR) In Liusha Bay

Halophila ovalis(R.BR) as advantage species of subtropical seaweed bed which has ability to form large seaweed beds in intertidal zone, so it plays an important ecological service function in coastal ecosystems. But due to the lack of understanding of the seaweed, the research of Halophila ovalis was almost blank in present. In recent years, Halophila ovalis of seagrass beds are suffered severe damage as influenced by human activities and natural factors, so it is very urgent to protect and repair measures of the seagrass beds. therefore, this research use an advantage species of seaweed in Liusha Bay——Halophila ovalis as research object, We carried on anniversary investigation of growth dynamic of Halophila ovalis in Liusha Bay by biological investigation means, and combined with the growth of environmental conditions, analysis the influence of environment factors on the growth. We made an analysis on anniversary of the dynamic characteristics of biochemical composition and nutrient content in Halophila ovalis. In addition, we studied the different level of nitrogen and phosphorus on the influence of growth characteristics of Halophila ovalis by adding nutrient experimental in the laboratory. It is show from the study results as followed:1. Physical and chemical factors in water presented seasonal variation characteristics in seaweed bed of Liusha Bay. Water temperature range for the whole year was 16.5~33.6 ℃, the mean value was 26.2 ℃. Salinity range for the whole year was 30.1~33.4‰, the mean value was 31.7‰. pH value variation was rang from7.75 to 8.43, the mean value was 8.02. The total annual rainfall was 1300 ~ 1500 mm, and mainly concentrated in the spring and summer which account for 90% of the whole year. Spring and summer of the tide occured in the evening, the autumn and winter spring tide occurred in the day.2. Nutrient content in Water and sediment of seaweed bed in Liusha Bay presents seasonal variation characteristics. the contents range variation of active phosphorus 、ammonium nitrogen、nitrate nitrogen、nitrite nitrogen in Water was 0.924~0.701 μM、0.478~5.33 μM、0.818~9.63 μM and 0.112~1.52 μM respectively, the mean value was 0.402 μM、2.04 μM、3.65 μM and 0.426 μM respectively. the contents range variation of active phosphorus、ammonium nitrogen、nitrate nitrogen + nitrite nitrogen in sediment was 7.83~20.4 μM、30.5~82.9 μM and 8.66~11.9 μM respectively, the mean value was 12.5 μM、51.8 μM、9.46 μM respectively.3. By means of annual investigation in March of 2014 to February of 2015, the average coverage for Halophila ovalis was 28.5%, average biomass was 12.5 gDW/m2 in Liusha Bay, coverage and biomass has the maximum value in summer and a minimum value in winter, which presents in summer significantly greater than in winter(P<0.001). Aerial and underground part of biomass of Halophila ovalis in different shore zone showed that: Littoral zone < Shore zone < Far shore zone, but aerial and underground part of biomass was no difference. AGR and RGR for Halophila ovalis appear negative values in autumn, which account for Halophila ovalis fall into recession in autumn. Chlorophyll and carotenoid content for Halophila ovalis was accumulated more in winter.4. By means of Person correlation analysis from coverage、biomass、 photosynthetic pigment and the main environmental factors of Halophila ovalis, we learn about that water temperature and nitrogen content was major environmental factor which influenced for growth of seasonal change of Halophila ovalis.5. The mean value for Soluble sugar content within the organization of Halophila ovalis(R.BR) was 19.3%, Soluble sugar content within the underground part was much higher than those in overground part(P<0.05). soluble protein content’s mean value of Halophila ovalis was 0.376 mg/g FW, and which within the overground part was much higher than those in underground part(P<0.01). Nitrogen and phosphorus content in average for Halophila ovalis was 19.2 mg N/g DW and 10.5 mg P/g DW respectively, N/P Ratio average value was 7.3<14, which presents Halophila ovalis was limited by nitrogen.6. By means of nitrogen and phosphorus add experiment in laboratory, the results show that Halophila ovalis in the lower level of nitrogen and phosphorus(N/P=2:1) which growth status was best.