Stable carbon isotope fractionation by marine phytoplankton in response to daylength, growth rate, and CO2 availability
Stable carbon isotope fractionation by marine phytoplankton in response to daylength, growth rate, and CO2 availability
复制标题
海洋浮游植物对日长、生长率和二氧化碳可用性的稳定碳同位素分馏
DOI：
--
复制
发表时间：
1999
期刊：
影响因子：
--
通讯作者：
I. Zondervan
中科院分区：
文献类型：
--
作者：
S. Burkhardt;U. Riebesell;I. Zondervan
在营养丰富的条件下，在高光强度的分批培养中，测量了在不同辐照周期中生长的 7 种海洋浮游植物物种的稳定碳同位素分馏 (ep )。与连续光照下的实验相比，当在 12:12 小时、16:8 小时或 18:6 小时光:暗 (L/D) 循环下培养时，所有物种都表现出显着更高的瞬时生长速率 (μ i )，定义为光周期期间的碳固定速率。在 16:8 h L/D 周期中，硅藻中肋骨条藻 (Skeletonema costatum)、Asterionella glacialis、Thalassiosira punctigera 和 Coscinodiscus wailesii（第 1 组）的同位素分馏比连续光照下低 4 至 6 ‰，我们将其归因于 μ i 的差异。相比之下，三角褐指藻、Weissflogii 海藻和甲藻 Scrippsiella trochoidea（第二组）中的 e p 对与日长相关的瞬时生长率差异基本上不敏感。由于其他研究报道了三角褐藻在 N 限制条件下的生长速率依赖性分馏，μ i 对分馏的相关影响显然取决于控制生长速率的因素。我们认为 e p 和 μ i /[CO 2,aq ] 之间的一般关系可能不存在。对于每组中的 1 个物种，我们测试了可变 CO 2 浓度 [CO 2,aq ] 对同位素牵引的影响。[CO 2,aq ] 的减少] 从约 26 到 3 µmol kg -1 导致 e p 下降了不到 3‰。这表明，在一些测试的物种中，μ i 响应日长变化对同位素分馏的影响相似甚至更大。在 24 和 48 小时的时间序列中，在 13 C 期间，较小物种的 e 1 往往更高。然而，藻类同位素组成（δ 13 C）的日振幅≤1.5‰，这表明δ 13 C的日变化相对较小。
Stable carbon isotope fractionation (e p ) of 7 marine phytoplankton species grown in different irradiance cycles was measured under nutrient-replete conditions at a high light intensity in batch cultures. Compared to experiments under continuous light, all species exhibited a significantly higher instantaneous growth rate (μ i ), defined as the rate of carbon fixation during the photoperiod, when cultivated at 12:12 h, 16:8 h, or 18:6 h light:dark (L/D) cycles. Isotopic fractionation by the diatoms Skeletonema costatum, Asterionella glacialis, Thalassiosira punctigera, and Coscinodiscus wailesii (Group 1) was 4 to 6‰ lower in a 16:8 h L/D cycle than under continuous light, which we attribute to diflerences in μ i . In contrast, e p in Phaeodactylum tricornutum, Thalassiosira weissflogii, and in the dinoflagellate Scrippsiella trochoidea (Group II) was largely insensitive to daylength-related differences in instantaneous growth rate. Since other studies have reported growth-rate dependent fractionation under N-limited conditions in P. tricornutum, μ i -related effects on fractionation apparently depend on the factor ( ontrolling growth rate. We suggest that a general relationship between e p and μ i /[CO 2,aq ] may not exist. For 1 species of each group we tested the effect on variable CO 2 concentration, [CO 2,aq ], on isotopic tractionation. A decrease in [CO 2,aq ] from ca 26 to 3 μmol kg -1 caused a decrease in e p by less than 3‰. This indicates that variation in μ i in response to changes in daylength has a similar or even greater effect on isotopic fractionation than [CO 2,aq ] in some of the species tested. In both groups e 1 tended to be higher in smaller species at comparable growth rates. In 24 and 48 h time series the algal cells became progressively enriched in 13 C during the day and the first hours of the dark period, followed by 13 C depletion in the 2 h before beginning of the following light period. The daily amplitude of the algal isotopic composition (δ 13 C), however, was ≤1.5 ‰, which demonstrates that diurnal vanation in δ 13 C is relatively small.