Effects Of Ocean Acidification And Increasing Temperature On The Photosynthesis And Nitrogen Metabolism Of Laminaria Japonica

Due to increased human activities, atmospheric CO2 levels increased year by year, which leads to global warming. Meanwhile the ocean as a buffer to absorb greenhouse gases by almost 30% CO2, prompting seawater pH decreases, and water chemistry system has undergone significant changes, and thus the formation of the "ocean acidification" phenomenon. The increasing temperature directly affectes the growth and biological metabolism of marine organisms.Ocean acidification produces a variety of positive, neutral and reverse impact on marine organisms as well. In this experiment, we studied Laminaria japonica mainly to manifest the effects of ocean acidification and temperature on the photosynthetic characteristics and nitrogen metabolism.The temperature range of shallow sea for Laminaria japonica survival the whole year is 5℃-25℃.So five temperature gradient was arranged,including 5℃,10℃,15℃,20℃ and 25℃,to detect the effects of temperature variation on Laminaria japonica.Then five CO2 concentration gradient was arranged, including 280ppm,400ppm,700ppm,1000ppm and 2000ppm,to detect the effects of different degree of acidification on the photosynthesis and nitrogen metabolism of Laminaria japonica.While the effects of temperature and acidification is not exist in isolation in the actual situation,we arranged cross experiment to study the combined impacts of ocean acidification and temperature on the photosynthetic characteristics and nitrogen metabolism of Laminaria japonica.Tht main results are as follows:The optimum temperature range for Laminaria japonica growth and metabolism is 10-15℃.The growth and biological metabolism was restrained and various physiological parameters oegan to aecime over 150.The increase of CO2 concentration promoted the growth of seaweed, and improved the efficiency of photosynthesis and nitrogen uptake to some extent.But the chemical equilibrium of the water was destroyed while CO2 concentration was too high, causing a lot of bad phenomena,much lower pH for example,which had an negative effect on the growth and metabolism of Laminaria japonica.High temperature inhibited the growth and biological metabolism of Laminaria japonica, while the inhibition was alleviated by the increasing of CO2 concentration to some extent.