Abstract:

Intertidal macroalgae experience continual alternation of photosynthesis between aquatic state at high tide and aerial state at low tide. The comparative photosynthetic responses to inorganic carbon were investigated in the common intertidal macroalga Ulva lactuca L. along the coast of Shantou between aquatic and aerial state. The inorganic carbon dissolved in seawater at present could fully (at 10 ℃ or 20 ℃) or nearly (at 30 ℃) saturate the aquatic photosynthesis of U. lactuca. However, the aerial photosynthesis was limited by current ambient atmospheric CO2 level, and such a limitation was more severe at higher temperature (20-30℃) than at lower temperature (10℃). The carbon saturated maximal photosynthesis of U. lactuca under aerial state was much greater than that under aquatic state at 10℃ and 20 ℃, while the maximal photosynthesis under both states was similar at 30℃. The aerial values of Km(CO2) for photosynthesis were higher than the aquatic values. On the contrary, the values of apparent photosynthetic CO2 conductance under aerial state were considerably lower than that under aquatic state. It was concluded that the increase of atmospheric CO2 would enhance the primary productivity of U. lactuca through stimulating the photosynthesis under aerial state during low tide.

在水生与气生状态下石莼光合作用对无机碳的响应
邹定辉1  高坤山1，2*

（1. 汕头大学科技中心海洋生物研究所，广东汕头515063；2. 中国科学院水生生物研究所，武汉430072）

摘要： 潮间带海藻光合作用总是处于水生 (高潮时 )与气生 (低潮时 )两种连续变化的环境状态下进行。对汕头沿岸常见的潮间带海藻石莼 (Ulvalactuca L .)在水生和气生不同状态下光合作用对无机碳的响应特性进行了比较研究。在水生状态下 ,现有海水中溶解性无机碳浓度能充分饱和 (10℃和 2 0℃时 )或接近饱和 (30℃时 )石莼的光合作用 ;而在气生状态下 ,石莼光合作用受大气CO2 浓度的限制 ,且这种限制作用在较高温度 (2 0 - 30℃ )下比在低温(10℃ )下更严重。在 10℃和 2 0℃时 ,石莼在气生状态下比在水生状态下具有更高的碳饱和最大光合速率 ;而在30℃时 ,石莼在这两种状态下的碳饱和光合速率相似。石莼光合作用的Km(CO₂ )值在气生状态下比在水生状态下高 ;而在气生状态下石莼对CO₂ 的表观光合导度远小于其在水生状态下的值。认为大气CO₂ 浓度升高将通过促进石莼在气生状态下的光合作用而增加其初级生产力。

关键词： 石莼；光合作用；无机碳；水生；气生；大气CO₂ 浓度升高

!通讯作者。E-mail:ksgao @ stu.edu.cn

Key words: Ulva lactuca, photosynthesis, inorganic carbon, aquatic, aerial, atmospheric CO2 rise