Study On The Ecological Adaptability And Intrusion Research Of Karenia Mikimoto

Marine biological invasion is a phenomenon that making the non-origin species introduced from the original distribution area to a new area,and cause certain damage to the of local marine ecosystems. Marine biological invasion has become one of the four major problems in world’s marine ecosystems. red tide with large-scale become the most typical of marine organism invasion problem in China’s, especially the invasion of harmful algae blooms. which caused irreparable damage, Karenia mikimoto would be one worthy of more attention.Karenia mikimotoi is toxic algae, and algal toxins could cause the death of nekton and benthos. Nearly 20 years, k.mikimotoi bloom happen in many sea aera of China,and caused serious damage to local marine ecosystems,and billions of RMB in economic losses to the marine aquaculture industry.Taking the harmful algae K.mikimotoi as the research object, under the ecological conditions of different environmental factors, ambient ratios of N and P,and different degrees of nutritional. Studying the competition between Skeletonema costatum and k.mikimotoi respectively in different nitrogen and ratio N and P,different initial Cha raito; combing with the experimental results and related literature,evaluated intrusion of K.mikimotoi through the introduction of alien marine organism invasion risk assessment system.1. Effects of different environmental factors on the growth of K.mikimotoi We study the effects of temperature, salinity and total suspended particles(TSS)effect on growth of K.mikimotoi. The results showed that the suitable growth temperature, salinity is 25 ℃ and 30‰ respectively. It can grow well between the temperature of 20.0-27.5℃ and salinity of 25‰-35‰. TSS K.mikimotoi could limits the growth of algae severely, the lower the content of TSS was more conducive to the growth. Three effects of environmental factors on the growth of K.mikimotoi were TSS>salinity> temperature.2.The influence of different ambient ratios of N and P and different degrees of nutritional to the K.mikimotoi growth.The most suitable ambient ratios of N and P of K.mikimotoi growth is 50, and maintain good growth in the range of 25-75, the improvement of nutrition level(oligotrophic, mesotrophic and eutrophic) is conducive to the growth of K.mikimotoi populations. In different trophic levels and environmental factors(temperature,salinity) jointly interference, the effect of nutrition level is higher than that of environmental factors on the growth of K.mikimotoi.3.Effects of different nitrogen and phosphorus ratio and different initial cell density on K.mikimotoi algae and S.costatum population competition When cultured alone, the best ambient ratios of N and P of K.mikimotoi and S.costatum are 50:1(N:150 mol/L, P:3 mol/L). In mixed culture, the environmental loading capacity(K) and growth rate(R) of these two microalgae were lower than that cultured alone. In all of ambient ratios of N and P, S. costatum are in advantage, the K.mikimotoi inhibition parameter β is higher than that of K.mikimotoi of S.costatum inhibition parameters α,and β: α increased with ambient ratios of N and P increased.When cultured alone, the initial density of the two species almost had no effect to microalgae K value; In mixed culture, when their initial Chl-a ratio is 1:1, 4:1 and 1:4,1:10, S.costatum occupy a dominant position; and when the initial Chl-a ratio is 10:1,K.mikimotoi occupied a dominant position. The results of filtrate culture showed that the two species of microalgae could affect each other, which may be due to the different growth strategies and the effects of microalgae Chemical action play a decisive role in the competition between the two species.4.Invasive risk assessment of K.mikimotoi algae.References to "alien marine species intrusion risk assessment model" as K.mikimotoi invasion risk assessment model, combining the experimental results and the relevant historical documents, determine the evaluation coefficient(intrusion risk index R and invasion potential P, severity index S), obtained by calculation of K.mikimotoi R, P and S values were 0.78, 0.613 and 0.478, intrusion risk level is high,which belongs to the high risk marine invasion of microalgae.