不同紫外波段对中肋骨条藻光合生理特性的影响

Effects of different ultraviolet wavelength bands on the photosynthetic physiological characteristics of Skeletonema costatum

人类活动导致臭氧层变薄和混合层变浅,迫使混合层的浮游植物暴露在更高的紫外辐射下。实验以中肋骨条藻(Skeletonema costatum)为研究对象,在自然光照条件下,通过在暗盒上方覆盖不同的截止型滤光板,获得不同波段紫外辐射,探讨不同紫外波段对其生理特性的影响。本实验通过在室外培养,模拟赤潮爆发状态,对中肋骨条藻进行7种不同紫外波段的处理(分别使用280、300、320、340、360、380、400 nm截止型滤光板)。实验结果表明:紫外辐射会显著抑制中肋骨条藻的光合固碳速率,随着紫外波段逐步被滤除,光合固碳速率越来越高;>280 nm和>300 nm波段下的比生长率显著低于>400 nm波段处理;280 nm^300 nm波段紫外对叶绿素a有显著的漂白效应,同时也会显著减少类胡萝卜素的含量;这表明紫外辐射对中肋骨条藻的抑制效应主要是紫外辐射B导致的,而紫外辐射A的作用不显著。在估测浮游植物海洋初级生产力的过程中,紫外辐射的作用往往被忽视。

Since the Industrial Revolution began around 1750,human activities have contributed substantially to climate change.Stronger short-wave ultraviolet(UV)radiation reaches the ground through depleted ozone layer existing in the earth’s atmosphere.At the same time,global warming has resulted in shallower and mixed seawater layers,thereby exposing phytoplankton to higher UV radiation.Red tide caused by algae blooms frequently occurs in coastal waters,and Skeletonema costatum is one of the typical algae species responsible for red tide.Studying the effects of different ultraviolet wavelengths on its physiological characteristics are of great significance.In this experiment,the species Skeletonema costatum was cultured outdoors,and the state of red tide was simulated.Then they were treated with UV bands of seven different wavelengths(using 280,300,320,340,360,380,and 400 nm cut-off filters,respectively).The experimental results showed that UV radiation could considerably reduce the rate of photosynthetic carbon fixation of Skeletonema costatum.The photosynthetic carbon fixation rate was increased as the UV bands were gradually filtered out;the specific growth rates of treatments at>280 nm and>300 nm were considerably lower than that of treatment at>400 nm;280 nm–300 nm had a significant bleaching effect on chlorophyll a,and it also considerably reduced the content of carotenoids;this study indicated that the inhibitory effect of UV on Skeletonema costatum is mainly caused by UV whereas the effect of ultraviolet A is not considerable.In the process of estimating the primary productivity of phytoplankton in the ocean,the role of ultraviolet radiation is often overlooked.Therefore,in the context of global warming,this study provides a certain reference value for accurately estimating the daily productivity of phytoplankton.