藻类光竞争模型构建及水体紊动对竞争的影响

Development of competition model of algae for light and the impact of turbulence on algal competition

光是藻类进行光合作用的重要能量来源,决定藻类的初始生产力,当多种浮游藻类共同生存时,会一起竞争光强.光竞争能力强的浮游藻类浓度增加,光竞争能力较弱的则减少,从而完成水体中浮游藻类优势藻的替代.本文通过在以往建立的单藻模型的基础上,耦合入竞争模型,构建两种(多种)浮游藻类光竞争模型,尝试通过数值模拟,研究不同水体紊动中竞争藻属分别取得竞争优势的机理.模拟结果表明:稳态水体中,竞争藻属的自身垂向迁移决定藻浓度的垂向分布,具有浮力调节能力的微囊藻属占据上层水体优势地位,并取得竞争优势;动态水体中,竞争藻属垂向分布均较为均匀,生长速率决定藻的竞争优势,小球藻属生长速率快,最终易取得竞争优势.此外,考虑浮游藻属的动态自遮蔽,会加速稳态水体中微囊藻属取得竞争优势,并限制动态水体中小球藻属的无限制生长,使得模拟结果更加符合实际情况.

Light intensity is a very important factor for algal growth as one of essential resources.In the nature,a number of algae species live together in water.The population of algae species,who has the advantage of acquiring light,will gain the population,and vice versa.In this paper,a competition model,based on the former uni-species model,was developed.Through numerical simulations,the mechanics of hydrodynamic turbulence on species competition were tried to be explained.The simulation results revealed that migration abilities of each species and the growth rate determined the advantage species in calm water and in turbulent water,respectively.In addition,the modified dynamic self-shading accorded the simulation results with the reality,which not only expedited the advantage of Microcystis in calm water but also restricted the unlimited population increase of Chlorella in turbulent water.