Benthic microalgae are more 13C-depleted than phytoplankton in temperate flooded rice fields
Benthic microalgae are more 13C-depleted than phytoplankton in temperate flooded rice fields
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温带水淹稻田中底栖微藻比浮游植物更缺乏 13C
DOI：
10.1007/s10333-020-00830-7
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发表时间：
2020
影响因子：
2.2
通讯作者：
Kikuchi Eisuke
中科院分区：
文献类型：
--
作者：
Yasuno Natsuru;Kanaya Gen;Takagi Yuya;Shikano Shuichi;Kikuchi Eisuke
研究了日本东北部3个淹水稻田中颗粒有机物（POM）δ 13 C水平的季节变化，POM主要由浮游植物和微型底栖植物组成，稻田施用不同类型的肥料（化学NPK、化学PK或有机肥）。一般而言，在静水淡水系统中，微型底栖植物的δ 13 C水平（约-26 ‰）高于浮游植物（约-32 ‰），这是由于在底栖边界层（BBL）中溶解无机碳（DIC）资源有限的情况下13 C富集。然而，我们的研究结果表明，POM比微型底栖植物更富集13 C，无论施肥类型如何。农田中POM和微型底栖植物δ 13 C的总体平均水平分别为− 27.5 ‰至− 25.2‰和− 30.3 ‰至− 27.0‰。相比之下，土壤有机质中的δ 13 C水平在时间上是稳定的，平均值在− 27.6 ‰到− 26.3‰之间。高δ 13 C水平是由于水稻系统中植物营养素生产力高和水分停滞条件下DIC有限，导致光合作用期间DI 13 C摄入。相反，微植物底栖生物使用更多的13 C-贫化DIC的BBL，这是微生物再生的SOM池。稻田微型底栖植物δ 13 C的季节变化规律相似，在6月下旬急剧下降，随后又回升。这可能是由于DIC的可用性或微型底栖植物的增长率在此期间的变化。研究结果为了解温带稻田湿地浮游藻类和微型底栖藻类生产者δ 13 C的变化提供了基础信息。
We investigated seasonal changes in theδ13C levels of particulate organic matter (POM), which mainly consist of phytoplankton and microphytobenthos from three flooded rice fields treated with different types of fertilizer (chemical NPK, chemical PK, or organic fertilizers) in northeast Japan. Generally, microphytobenthos in lentic freshwater systems show higher levels ofδ13C (about− 26‰) than phytoplankton (about− 32‰) due to13C enrichment under limited resources of dissolved inorganic carbon (DIC) in the benthic boundary layer (BBL). However, our results showed that POM was more13C-enriched than microphytobenthos regardless of the type of fertilizer applied. Overall mean POM and microphytobenthosδ13C levels in the fields ranged from − 27.5 to − 25.2‰ and − 30.3 to − 27.0‰, respectively. In contrast,δ13C levels in soil organic matter were temporally stable, with means ranging from − 27.6 to − 26.3‰. Highδ13C levels in POM were due to limited DIC under conditions of high phytoplanktonic productivity and water stagnation in paddy systems, resulting in DI13C intake during photosynthesis. Conversely, microphytobenthos used more13C-depleted DIC in the BBL, which was microbially regenerated from the SOM pool. Microphytobenthos in the rice fields showed similar seasonal variations inδ13C, decreasing sharply in late June and then increasing again. This was possibly caused by changes in DIC availability or the growth rates of microphytobenthos during that period. The present results provide basal information about producer-specificδ13C variations in two major microalgal producer groups, phytoplankton and microphytobenthos, in temperate rice paddy wetlands.