| 摘要: |
| 海藻场是生物多样性最高的生态系统之一, 其内部的沉积物有机质是支撑海藻场生物多样性的重要物质基础之一。本研究以浙江省嵊山岛北部无人村沿岸的天然海藻场为研究对象, 在大型海藻凋落期6~8月采集沉积物和端元生物样本, 分析了沉积物样本的粒径组成、总有机碳 (TOC)、总氮(TN)、碳氮比值(C/N)和碳氮稳定同位素(δ13C和δ15N), 通过贝叶斯稳定同位素混合模型评估了沉积物有机质的来源及变化规律。结果显示, 1)海藻场沿岸沉积物中粉砂占比最大, 砂的占比最低, 沉积物类型为黏土质粉砂; 2)沉积物TOC、TN、C/N、δ13C和δ15N范围分别为0.70%~2.41%、0.11%~0.41%、5.53~6.48、–21.79‰~–19.60‰和1.56‰~4.26‰, 在空间分布上, TOC与TN含量均随离岸距离增加而下降; 3)沉积物粒径组成、C/N比值、δ13C和δ15N之间的关系显示沉积物有机质主要来源于大型海藻和浮游植物的混合贡献; 4)根据贝叶斯同位素混合模型计算结果显示, 大型海藻对沉积物有机质贡献率在2.30%~45.60%, 在空间分布上, 大型海藻对沉积物有机质的贡献率随离岸距离增加而下降; 5)海藻碎屑产生量和沉积物有机碳沉积量评估结果显示, 大型海藻产生的碎屑有机质中有11.98%进入海藻场及沿岸海域的表层沉积物中。本研究为评估海藻场碎屑的产生规模和时空分布, 以及渔业资源养护功能提供了数据支撑。 |
| 关键词: 海藻场 沉积物有机质 稳定同位素 来源 贡献率 |
| DOI：10.11759/hykx20210531003 |
| 分类号:Q178.1 |
| 基金项目:国家自然科学基金(41876191); 现代农业产业技术体系专项(CARS-50); 国家重点科研计划(2019YFD0901303) |
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| Distribution characteristics and sources of organic matter in surface sediments along the coast of natural seaweed bed |
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ZHANG Jian, LI Xunmeng, CHENG Xiaopeng, ZHANG Shouyu, HUANG Hong, WANG Kai
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College of Marine Ecology and Environment, Shanghai Ocean University, Shanghai 201306, China
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| Abstract: |
| Seaweed beds are among the most biodiverse ecosystems, and sedimentary organic matter is one of the important material foundations supporting the biodiversity of seaweed beds. In this study, the natural seaweed bed along the coast of northern Shengshan Island, Zhejiang Province, was selected as the research area, and sediments and endmember samples were collected from June to August during macroalgae littering. The grain-size composition, total organic carbon (TOC), total nitrogen (TN), carbon–nitrogen ratio (C/N), and stable carbon and nitrogen isotopes (δ13C and δ15N) of the sediment samples were analyzed. The source and variation of the sedimentary organic matter were evaluated using the Bayesian stable isotope mixing model. The results are summarized as follows: 1) The silt content was the largest, and the sand content was the lowest in the sediments along the seaweed bed. Thus, the sediment type was clayey silt. 2) The TOC, TN, C/N, δ13C, and δ15N ranges of sediments were 0.70%–2.41%, 0.11%–0.41%, 5.5 ‰–6.48‰, -21.79‰–-19.60‰, and 1.56‰–4.26‰, respectively. In terms of spatial distribution, the TOC and TN decreased with increasing offshore distance. 3) The relation among the grain-size composition, C/N ratio, δ13C, and δ15N showed that the sedimentary organic matters were mainly derived from the mixed contribution of macroalgae and phytoplankton. 4) According to the Bayesian isotope mixing model, the contribution rate of macroalgae to sediment organic matter was 2.30%–45.60%. In terms of spatial distribution, the contribution rate of macroalgae to sediment organic matter decreased with increasing offshore distance. 5) The assessment results of macroalgal detritus production and sediment organic carbon deposition showed that 11.98% of the detrital organic matter produced by macroalgae was deposited into the surface sediments along the seaweed bed. This study provides data support for assessing the production scale and spatiotemporal distribution of macroalgae debris and the conservation function of fishery resources of the seaweed bed. |
| Key words: seaweed bed sedimentary organic matter stable isotope source contribution rate |
