Leaching of dissolved organic matter from seagrass leaf litter and its biogeochemical implications

作     者：LIU Songlin JIANG Zhijian ZHOU Chenyuan WU Yunchao ARBI Iman ZHANG Jingping HUANG Xiaoping TREVATHAN-TACKETT Stacey M. 

作者机构：Key Laboratory of Tropical Marine Bio-resources and EcologySouth China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301China University of Chinese Academy of SciencesBeijing 100049China School of Life and Environmental SciencesCentre for Integrative EcologyDeakin UniversityVictoria 3125Australia 

出 版 物：《Acta Oceanologica Sinica》 (海洋学报（英文版）)

年 卷 期：2018年第37卷第8期

页      面：84-90页

核心收录：

学科分类：0710[理学-生物学] 0908[农学-水产] 07[理学] 0707[理学-海洋科学] 071004[理学-水生生物学] 

基　　金：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 

主　　题：dissolved organic matter Thalassia hemprichii Enhalus acoroides leaf litter leaching 

摘      要：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 4×10~3 mol/d DOC, 1.4×10~3 mol/d DON and 25 mol/d DOP into the seawater. In addition to providing readily a