Effects of sea surface warming on the production and composition of dissolved organic matter during phytoplankton blooms: results from a mesocosm study
Effects of sea surface warming on the production and composition of dissolved organic matter during phytoplankton blooms: results from a mesocosm study
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DOI：
10.1093/plankt/fbq122
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发表时间：
2011-03-01
影响因子：
2.1
通讯作者：
Riebesell, Ulf
中科院分区：
文献类型：
--
作者：
Engel, Anja;Haendel, Nicole;Riebesell, Ulf
进行了一项实验研究，以测试预估的海面变暖（根据IPPC情景）对寒冷海域（< 4℃）海洋浮游植物大量繁殖期间溶解有机物（DOM）积累和组成的影响。8个类似于1400 L的天然海水培养皿中，分别以+0、+2、+4、+6℃的温度培养2个重复培养皿。封闭的水体最初被无机营养物施肥，以诱导浮游植物大量繁殖，然后以硅藻为主。在4周的时间里，溶解的组合碳水化合物（DCCHO）和溶解的氨基酸（DAA）被确定为新鲜生产的，不稳定到半不稳定的DOM的主要成分。在所有中胚层中，DCCHO浓度在叶绿素a浓度达到峰值后急剧增加，此时营养物逐渐枯竭。温度升高导致DCCHO和联合葡萄糖的积累更早、更快、更高。在+0、+2、+4和+6℃处理下，DCCHO产量分别占总组合碳水化合物的35%、40%、49%和59%。DAA的积累较为连续，平均积累速率为0.79 +/- 0.20 nmol L-1 h(-1)，但不受温度升高的影响。由于DCCHO积累量的增加，DOM的C:N比值在开花过程中显著增加，且温度较高。我们的研究表明，变暖增加了浮游植物细胞外碳水化合物的释放，因此，可能会影响未来寒冷海域微生物循环的自下而上控制。
An experimental study was conducted to test the effects of projected sea surface warming (according to the IPPC scenarios) on the accumulation and composition of dissolved organic matter (DOM) during marine phytoplankton blooms in cold seas (< 4 degrees C). Eight mesocosms (similar to 1400 L) were filled with natural seawater, and two replicate mesocosms each were incubated by raising temperature by +0, +2, +4 and +6 degrees C, respectively. The enclosed water was initially fertilized with inorganic nutrients to induce the development of phytoplankton blooms, which were then dominated by diatoms. Over a 4-week period, dissolved combined carbohydrates (DCCHO) and dissolved amino acids (DAA) were determined as major components of freshly produced, labile to semi-labile DOM. In all mesocosms, the increase in DCCHO concentration occurred sharply after the peak of chlorophyll a concentration, when nutrients became depleted. Rising temperature resulted in an earlier, faster and higher accumulation of DCCHO and of combined glucose predominantly. DCCHO yielded a maximum percentage of 35, 40, 49 and 59% of total combined carbohydrates in the +0, +2, +4 and +6 degrees C treatments, respectively. Accumulation of DAA occurred more continuously and at an average rate of 0.79 +/- 0.20 nmol L-1 h(-1), but was not affected by rising temperature. Owing to the higher accumulation of DCCHO, the C:N ratio of DOM increased strongly during the course of the bloom, with higher ratios in the warmer treatments. Our study suggests that warming increases the extracellular release of carbohydrates from phytoplankton and, therefore, may affect the bottom-up control of the microbial loop in cold seas in the future.