| LIU Songlin,JIANG Zhijian,ZHOU Chenyuan,WU Yunchao,ARBI Iman,ZHANG Jingping,HUANG Xiaoping,TREVATHAN-TACKETT Stacey M.. 2018. Leaching of dissolved organic matter from seagrass leaf litter and its biogeochemical implications. Acta Oceanologica Sinica, 37(8):84－90 |
| Leaching of dissolved organic matter from seagrass leaf litter and its biogeochemical implications |
| 海草凋落叶的溶解有机物的释放及其生物地球化学意义 |
| Received:November 09, 2017 Revised:February 24, 2018 |
| DOI：10.1007/s13131-018-1233-1 |
| Key words:dissolved organic matter Thalassia hemprichii Enhalus acoroides leaf litter leaching |
| 中文关键词: 溶解有机物 泰来草 海菖蒲 凋落叶 释放 |
| 基金项目:The National Basic Research Program of China under contract Nos 2015CB452905 and 2015CB452902; the National Natural Science Foundation of China under contract No. 41730529; the National Specialized Project of Science and Technology under contract No. 2015FY110600. |
| Author Name | Affiliation | E-mail | | LIU Songlin | Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China
University of Chinese Academy of Sciences, Beijing 100049, China | | | JIANG Zhijian | Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China | | | ZHOU Chenyuan | Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China
University of Chinese Academy of Sciences, Beijing 100049, China | | | WU Yunchao | Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China
University of Chinese Academy of Sciences, Beijing 100049, China | | | ARBI Iman | Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China
University of Chinese Academy of Sciences, Beijing 100049, China | | | ZHANG Jingping | Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China | | | HUANG Xiaoping | Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China
University of Chinese Academy of Sciences, Beijing 100049, China | xphuang@scsio.ac.cn | | TREVATHAN-TACKETT Stacey M. | School of Life and Environmental Sciences, Centre for Integrative Ecology, Deakin University, Victoria 3125, Australia | |
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| Abstract: |
| Dissolved organic matter (DOM) represents a significant source of nutrients that supports the microbial-based food web in seagrass ecosystems. However, there is little information on how the various fractions of DOM from seagrass leaves contributed to the coastal biogeochemical cycles. To address this gap, we carried out a 30-day laboratory chamber experiment on tropical seagrasses Thalassia hemprichii and Enhalus acoroides. After 30 days of incubation, on average 22% carbon (C), 70% nitrogen (N) and 38% phosphorus (P) of these two species of seagrass leaf litter was released. The average leached dissolved organic carbon (DOC), dissolved organic nitrogen (DON) and dissolved organic phosphorus (DOP) of these two species of seagrass leaf litter accounted for 55%, 95% and 65% of the total C, N and P lost, respectively. In the absence of microbes, about 75% of the total amount of DOC, monosaccharides (MCHO), DON and DOP were quickly released via leaching from both seagrass species in the first 9 days. Subsequently, little DOM was released during the remainder of the experiment. The leaching rates of DOC, DON and DOP were approximately 110, 40 and 0.70 μmol/(g·d). Leaching rates of DOM were attributed to the nonstructural carbohydrates and other labile organic matter within the seagrass leaf. Thalassia hemprichii leached more DOC, DOP and MCHO than E. acoroides. In contrast, E. acoroides leached higher concentrations of DON than T. hemprichii, with the overall leachate also having a higher DON:DOP ratio. These results indicate that there is an overall higher amount of DOM leachate from T. hemprichii than that of E. acoroides that is available to the seagrass ecosystem. According to the logarithmic model for DOM release and the in situ leaf litter production (the Xincun Bay, South China Sea), the seagrass leaf litter of these two seagrass species could release approximately 4×103 mol/d DOC, 1.4×103 mol/d DON and 25 mol/d DOP into the seawater. In addition to providing readily available nutrients for the microbial food web, the remaining particulate organic matter (POM) from the litter would also enter microbial remineralization processes. What is not remineralized from either DOM or POM fractions has potential to contribute to the permanent carbon stocks. |
| 中文摘要: |
| 溶解的有机物质（DOM）是一种重要的营养物质，并支持海草生态系统中的微生物食物网。然而，关于海草凋落叶释放的不同组分的DOM对沿岸生物地球化学影响的研究较少。因此，我们利用热带海草泰来草和海菖蒲进行了为期30天的凋落叶释放实验。在30实验后，海草凋落叶平均释放出22%的碳（C）、70%氮（N）和38%的磷（P），其中，释放出的溶解有机碳（DOC）、溶解有机氮（DON）和溶解有机磷（DOP）分别约占其总释放的55%、95%和65%。在没有微生物的条件下，约75%的DOC、单糖（MCHO）、DON和DOP在前9天从海草凋落叶迅速释放，仅有小部分的DOM在实验的剩余培养时间释放。在30天的培养期内，DOC、DON和DOP的释放速率分别为110、40和0.7μmol/（g.d），这主要是由于海草叶片中的非结构性碳水化合物和其他活性有机物的释放。泰来草比海菖蒲释放出更多的DOC、DOP和MCHO，但海菖蒲释放更多的DON并有更高的DON： DOP比率。这些结果表明，泰来草比海菖蒲能释放出更多的DOM。根据DOM释放的对数模型和原位海草的凋落量（海南新村湾），这两种海草的海草叶凋落物可向海水中释放约4×103 mol/d， 1.4×103 mol/d DON和25 mol/d DOP。这些DOM除了为微生物食物网提供现成的营养物质外，凋落叶中残留的颗粒有机物（POM）也将进入微生物再矿化过程。凋落物中没有矿化的DOM或POM组分有可能形成永久碳储量。 |
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