Effects Of Phosphorus And Illumination On Growth Of Laminaria Japonica And Respond Of Microalgae Interaction To Phosphorus And Heavy Metals

Firstly, this thesis investigate the effects of phosphorus and illumination on the growth of Laminaria japonica. Then studied the interaction between microalgae under the influence of different phosphorus concentrations. In the experiment, the new culture method "filter membrane connecting multi-microalgae culture" were established. At last, using this method to study the interaction between microalgae under the influence of heavy metals.Results show:1.Effects of phosphorus and illumination on the growth of Laminaria japonicaDuring our experiment the marine microalgae have the similar trend:their relative cell count decreased with the phosphorus concentration decreasing. The cell growth of mix-cultured Phaeodactylum tricornutum was inhibited by Chlorella vulgaris and Chlorella vulgaris is enhanced by Phaeodactylum tricornutum. Under low P concentration the photosynthesis is weak, indicating that low P concentration inhibite algal’s photosynthesis, so algae at low P conditions are subject to growth stress.The QY and Fv/Fo of mix-cultured Phaeodactylum tricornutum is higher than single-cultured Phaeodactylum tricornutum. and the difference is significant (P<0.05), the difference of Chlorella vulgaris is not significant. For green algae and diatoms,in terms of the P element competitive, the green algae is predominate.2.The interaction between microalgae.under the influence of different phosphorus concentrationsPhosphorus concentration and illumination have a great impact on the growth of Laminaria japonica. High light and low phosphorus concentration will cause some damage on physiological conditions. During the experiment, the Laminaria japonica of 24000 lux and 0.64mg/L,0.32mg/L occured white rotten firstly. But finally,the Laminaria japonica of 30000 lux and 0mg/L,0.08mg/L became white rotten seriously. Corresponding SOD, POD activity rose to the highest, but the last day decrease to minimize, under the conditions Laminaria japonica has been severely damaged.Meanwhile, the growth is measured, the high illumination and high P group growing fastest. Under high light and low P conditions, SOD, POD activity is higher. We concluded that white rot is caused together by high light and low phosphorus.3.The interaction between microalgae,under the influence of heavy metalsDuring our experiment the two marine microalgae have the similar trend:their relative growth rate K gradually decreased with the increasing concentration of heavy metals in the experiment concentration. The result show that toxic effects of three kinds of heavy metal irons was obviously different, the trend was Cu2+>Cd2+>Zn2+: Under the influence of three heavy metals, mix-cultured Phaeodactylum tricornutum is inhibited by Chlorella vulgaris And at certain concentrations, mix-cultured Chlorella vulgaris is enhanced by Phaeodactylum tricornutum. The experimental results show that, under certain ions stimulation.the mix-cultured microalgae produced allelopathy.1)Cd2+ affects the growth of Chlorella vulgaris and Phaeodactytum tricornutum, and low concentration promoted, high concentration inhibited. Wherein the adaptability of Phaeodactylum tricornutum is better than Chlorella vulgaris, the photosynthesis of Phaeodactylum tricornutum is strong, vitality is more exuberant. Therefore, the inhibition of Cd2+ is more significant for the survival of Chlorella vulgaris.2)Zn2+ affects the growth of Chlorella and Phaeodactylum tricornutum, and low concentration promoted, high concentration inhibited. Wherein the adaptability of Chlorella vulgaris is better than Phaeodactylum tricornutum,the photosynthesis of Chlorella vulgaris is strong,vitality is more exuberant. Therefore, the inhibition of Zn2+ is more significant for the survival of Phaeodactylum tricornutum.3)The growth of Chlorella vulgaris and Phaeodactylum tricornutum are both inhibited by Cu2+. Under different Cu2+ concentrations, the photosynthesis of Chlorella vulgaris increased slowly as the culture time increased. Phaeodactylum tricornutum photosynthes increased at first and then began to weaken, so the adaptability of Chlorella vulgaris is better than Phaeodactylum tricornutum. Therefore, the inhibition of Cu2+ is more significant for the survival of Phaeodactylum tricornutum.