光照与东海近海中肋骨条藻（Skeletonema costatum）赤潮发生季节的关系

利用船基现场培养实验和模型计算的方法,研究了光照与东海近海春夏季均能发生中肋骨条藻赤潮的关系.结果表明,中肋骨条藻生长的最适光照强度(Iopt)随水温(t)的增加呈"慢升快降"的不对称"倒V"形变化特征,在25℃左右Iopt最大,为121.6 W·m-2, Iopt-t中曲线符合Blanchard方程;由东海海表水温计算的中肋骨条藻Iopt的季节变化特征与东海海面光照强度、海水透明度的季节变化基本同步(R2=0.907±0.115, P<0.001),且滞后于海面光照强度2个月左右,这使春夏季海水中光照最适宜生长的水层均为全年最厚(6m左右).可见,中肋骨条藻对光照的适应性很强,海区海水光照的适宜性是春夏季均能形成大规模中肋骨条藻赤潮的重要原因之一.

Role of Irradiance on the Seasonality of Skeletonema costatum Cleve Blooms in the Coastal Area in East China Sea

With field culture experiments and model calculations, the role of light on why in both spring and summer Skeletonema costatum Cleve blooms can occur in the coastal area in East China Sea were studied. The results show that the growth optimal light intensity (I(opt)) of S. costatum increases gradually to a maximum of 121.6 W x m(-2) with temperature (t) up to 25 degrees C, and a rapid decline in I(opt) accompanies further increases in t beyond 25 degrees C. Such an asymmetric inverse V-shape I(opt)-t curve can be well described by Blanchard's equation. By this equation, I(opt) of each month was calculated based on monthly sea surface temperature, and though changes about 2 months later than light intensity above sea surface (I(0)), I(opt) is closely correlated with seasonal I(0) and transparency of sea water (R2 = 0.907 +/- 0.115, p < 0.001), which indicates that S. costatum adapts to the seasonality of light in sea water in the coastal area by varying I(opt) seasonally. Such an adaptive strategy leads to thick (about 6 m) light-optimal water layers for growth from early spring to late summer. The high adaptability to light and light optimum characteristics in sea water is one of the important reasons for S. costatum blooms in the both seasons in the coastal area in ECS.