海水酸化对米氏凯伦藻和盐生杜氏藻种群增长和种间竞争的影响

OCEAN ACIDIFICATION ON POPULATION GROWTH AND INTER-SPECIES COMPETITION BETWEEN KARENIA MIKIMOTOI AND DUNALIELLA SALINA

大气中CO_2浓度升高导致的海水酸化改变了海洋生物赖以生存的化学环境,将对其生长、繁殖和代谢产生深远影响。本研究采用实验生态学的方法,以米氏凯伦藻(Karenia mikimotoi)和盐生杜氏藻(Dunaliella salina)为研究对象,探究在海水酸化条件下两种微藻种群增长和种间竞争关系的变化。结果发现:(1)在单培养体系中,随着二氧化碳浓度升高,米氏凯伦藻的环境负载能力(K)升高,而对其生长率进入拐点的时间(T_p)、内禀增长率(r)、进入指数增长期(T_(Ep))和静止期的时间(T_(Sp))均无显著性影响;对盐生杜氏藻而言,二氧化碳浓度升高显著降低了盐生杜氏藻的T_p和r值,而对其K、T_(Ep)、T_(Sp)均无显著性影响;(2)在共培养体系中,两种微藻的K值均受到显著抑制,与单培养体系相比差异显著(P<0.05);二氧化碳升高改变了两种微藻的竞争关系,微藻之间的竞争表现为向有利于米氏凯伦藻的方向发展。(3)米氏凯伦藻去藻过滤液对盐生杜氏藻产生抑制作用,二氧化碳浓度升高加剧了这种抑制作用。

The effect of CO2-induced ocean acidification on population growth and inter-species competition between microalgae Karenia mikimotoi and Dunaliella salina were investigated in different pCO2 at 390（modern）, 1000（predicted value in 2100）, and 2000（predicted value in 2300） ppmv（parts per million by volume） under controlled laboratory conditions. The results showed that in mono-culture, pCO2 could significantly increase the maximum environmental capacity（K） of K. mikimotoi, while had no significant effects on the time at inflexion point（Tp）, the intrinsic rate of increase（r）, the time for entering exponential（TEp）, and stationary growth phases（TSp）; for D.salina, the values of r and Tpdecreased with elevated pCO2, while the value of K, TEp and TSp were not significantly affected by elevated pCO2. Both K values of the microalgae in co-culture were inhibited as compared to mono-culture（P〈0.05）, and their competition changed simultaneously with elevated pCO2. It seemed that elevated pCO2 broke the competitive balance and shift the competition gradually in favor of K. mikimotoi. In the filtrate cultivation experiment, we found that K. mikimotoi filtrate could significantly inhibit the growth of D. salina, and the inhibitory effect was more significant under higher pCO2 conditions.