五种典型藻类对C，N，P吸收动力学分析及种间竞争模拟

目的:获得五种典型藻类(甲藻属微小亚历山大藻(Alexandrium minutum)和锥状斯氏藻(Scrippsiella trochoidea),赤潮硅藻中肋骨条藻(Skeletonema costatum)以及绿藻属杜氏藻(Dunaliella salina)和青岛大扁藻(Platymonas helgolandica tsingtaoensis))对C,N,P营养的吸收动力学参数,并利用经典藻类种间竞争模型,构建一个藻类混合共存的生态平衡体系,揭示藻类种间竞争规律,为赤潮爆发机制和预测的研究提供一个新思路。方法:监测批次培养过程中藻体的生长规律以及培养基中C,N,P营养的消耗,计算出藻类营养吸收动力学参数,将参数代入Huisman-Weissing竞争模型,模拟藻类种间竞争。结果:(1)在单独培养条件下,杜氏藻具有最高的比生长率(0.834 d~(-1))和最大细胞浓度(3.4×10~6 cells/mL),锥状斯氏藻和微小亚历山大藻的比生长率μ和最大细胞浓度与其它三种藻相比均明显偏低,p0.01;(2)随着环境总碳浓度从5 mM提高到20 mM,五种藻的比生长率和最大细胞浓度均显著上升,其中杜氏藻和青岛大扁藻对C浓度改变的响应更加敏感;(3)杜氏藻和中肋骨条藻理论最大比生长率(μmax)明显高于其它三种藻类,锥状斯氏藻和微小亚历山大藻对C,N,P营养盐的需求量相比于其它三种藻明显偏高,p0.01;(4)藻类共生平衡系统中,N营养添加有利于杜氏藻和中肋骨条藻发挥更好的种间竞争优势,P营养添加有利于微小亚历山大藻和锥状斯氏藻发挥种间竞争优势;结论:不同环境条件下,五种藻类最大比生长速率μmax和营养吸收半饱和常数Ks直接影响它们的种间竞争能力,基于藻类动力学参数的种间竞争模型为赤潮爆发机制和预测的研究提供一个新思路。

The Investigation on C, N, P Nutrient Consumption Kinetics and Simulated Inter-specific Competition of Five Typical Microalgal Species

ABSTRACT Objective: In this study, two dinoflagellate species (Alexandrium minutum, Scrippsiella trochoidea), one diatom species (Skeletonema costatum), and two green algae (Dunaliella salina, Platymonas helgolandica tsingtaoensis) are selected as the experimental subjects to obtain their main kinetic parameters for carbon, nitrogen and phosphorous absorption, and then we build a coexisting balanced system for several algae by the typical algal inter-species competition model, from which the rules of algal inter-species competition are revealed, providing a new thinking for the study of the mechanism and prediction of algae bloom. Methods: By adding different concentrations of nutrients into the ecosystem, the breakage of the eco-balance as well as the formation of a new balance were simulated to study the impact of the sudden changes in nutrient concentrations on the competitive relations among those species. Results: (1) in the single batch culture, Dunaliella salina achieved the highest cell concentration (3.4×10⁶ cells/mL) and the maximum specific growth rate (0.834 d^-1), while Alexandrium minutum and Scrippsiella trochoidea presented a relatively lower level of growth; (2) Both the specific growth rate and the highest cell counts for each species were found increased with carbon concentration. Both Dunaliella salina and Platymonas helgolandica tsingtaoensis demonstrated a higher sensitivity to the changes in carbon concentration; (3) according to the kinetics analysis, the maximum specific growth rate for either Dunaliella salina or Skeletonema costatum was significantly higher than the other species. Both Alexandrium minutum and Scrippsiella trochoidea showed the greater saturation constants for carbon, nitrogen and phosphorus compared to the others; (4) additional nitrogen injection brought competitive advantages to Dunaliella salina and Skeletonema costatum, while adding phosphorus to the system was found beneficial to the competition of Alexandrium minutum and Scrippsiella trochoidea. Conclusion: The maximum specific growth rate and Ks of five algae can directly affect their inter-species competition under different environmental conditions. The inter-species competition model based on nutrient consumption kinetics provides the mechanism and forecasting of algae blooms with a new thinking.