Study Of Effects Of Spectrum On The Growth Of Skeletonema Costatum And Prorocentrum Lima

Harmful algal bloom is the abnormal phenomenon which the marine phytoplankton fulminant breeding to cause discoloration of the water body. It is the marine disaster which harasses many coastal countries, and has seriously hampered the sustainable economic development of coastal countries, and many coastal countries attach great importance to it. The red tide brings serious harm into marine ecological balance, marine fisheries and aquatic resources as well as human health. There are a wide variety of phytoplankton can caused red tide, such as the diatoms and dinoflagellates are main algae species of marine phytoplankton species, they are the typical dominant species of the formation of red tide, thus researchers are particularly concerned about them. Skeletonema costatum is one of the dominant species which causes red tide, and it has a eurythermal and euryhaline, that have widely distributed in the world sea. Prorocentrum Lima is an attached nature of dinoflagellate which can produce diarrhetic shellfish poison, and it widely distributed in the world sea also. The mechanism of occurrence of red tide is very complex and has not yet been identified, however, initial analysis showed that the factors of the occurrence of red tide relate to sea temperature, salt, nutrients and light and other factors. The light is a major environmental factor of the occurrence of red tide and one of the most important environmental factors on the growth of red tide algae. Therefore, the study of light on the growth of the red tide algae is very meaningful work.Light as an important ecological factor on affecting the growth of microalgae, that mainly from three aspects, including the photoperiod, light intensity and spectral to influence its growth. It is reported that few studies have reported on Skeletonema costatum and Lima Prorocentrum, mainly concentrated in the Photoperiod and light intensity. From the light source point of view, the study of white light on the growth of microalgae are most, however, less research on the special light source, especially the impact of spectrum on the growth of red tide algae. LED as a new type of light source, has high stability, low energy consumption, applicability, short response time, multi-color light, etc., and has been widely used in eco-lighting and display.In this work, we use the monochromatic light-emitting diode (LED) as the light source and study the effects of three monochromatic lights and its combination on the growth of Skeletonema costatum and Prorocentrum Lima, meanwhile discuss the effects of different spectra on the growth of microalgae from the three aspects of the spectral absorption coefficient, saturation light intensity and growth rate. The results show that:The light intensity on the growth of the two red tide algae have a significant effect, there is an optimal light intensity in each light for Skeletonema costatum and Prorocentrum Lima, and its growth will be inhibited while higher or lower than the saturation intensity. For the monochromatic light, the saturation light intensities of Skeletonema costatum and Prorocentrum Lima are both the lowest in the blue light, and the saturation light intensity of Skeletonema costatum and Prorocentrum Lima about is40μmol·m-2·s-1and60μmol·m-2s-11, respectively, the saturation light intensities of Skeletonema costatum is the highest in the green light(50μmol·m-2·s-1), and the value of Prorocentrum Lima is in the red light(80μmol·m-2s-1). Overall, the Lima Prorocentrum optimum light intensity is higher than Skeletonema costatum optimal light intensity.The effect of different spectra on the growth of the two red tide algae is significant differences. The growth rates of Skeletonema costatum and Prorocentrum Lima are both the highest in the blue light within saturated light intensity, and the growth rate of Skeletonema costatum is better than green in the red light, and that the growth rate of Prorocentrum Lima is better than red light in the green light. In the same light intensity, the combination of two light is more conducive to growth of algae than either a monochromatic light alone.It is concluded that the relationship of the spectral absorption coefficient of the two algae and its growth rate and saturation intensity, the growth rates of Skeletonema costatum and Prorocentrum Lima are positive correlation with the spectrum absorption coefficient within saturated light intensity, saturated light intensities are negative correlation with the spectrum absorption coefficient in the monochromatic light.The results show that the influence of monochromatic light on the growth of Skeletonema costatum and Prorocentrum Lima, and it provides a basis for further study of other types of red tide algae and provides a basis information for the generation mechanism of the red tide.