| 摘要: |
| 99-4航次对南沙珊瑚礁区进行了考察, 利用现场投放沉积物捕捉器采集沉降颗粒物样品, 从生物与非生物体系两个侧面对南沙珊瑚礁生态系的碳循环作了深入的研究。结果表明, 无机碳是珊瑚礁生态系中各种样品碳的主要存在形式, 总碳的收支主要受到溶解平衡与钙化作用的控制。有机碳在珊瑚礁泻湖中具有很高的循环效率, 泻湖中垂直转移的颗粒有机碳有93%以上在进入沉积物之前被释放, 其中生物碎屑的颗粒有机碳释放率约为99%。珊瑚礁植物尤其是与珊瑚共生的虫黄藻等的光合作用以及珊瑚礁的拟流网模型、休渔模型分别代表了构成珊瑚礁有机碳循环的两个主要方面, 即: 高效循环和稳定补充。因而珊瑚礁保护应当重点保护珊瑚礁水环境和生物多样性资源。
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| 关键词: 碳循环,珊瑚礁生态系,南沙 |
| DOI：10.11693/hyhz200306002002 |
| 分类号: |
| 基金项目:国家杰出青年科学基金资助项目,49925614号;中国科学院创新重大项目,KZCX1-SW-01-08号 |
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| CARBON CYCLING IN NANSHA CORAL REEF ECOSYSTEM, SOUTH CHINA SEA |
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SONG Jin-Ming, ZHAO Wei-Dong, LI Peng-Cheng, Lü Xiao-Xia
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Institute of Oceanology, The Chinese Academy of Science
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| Abstract: |
| Carbon cycling research is one of the key issues in research of coral reef ecosystem, which relates to the sustainable development of reef ecosystem. The main scientific problems include carbon form and species in its cycle, carbon budget in coral reef ecosystem and organism′s function. Most researches have been undertaken for abiogenic particulate carbon in Nansha Islands coral reefs for past ten years. A systemic research on carbon cycle in coral reef ecosystem is necessary. During the 99-4 cruise, integrated studies on both biotic and abiotic systems in terms of the regulation of carbon cycling in the entire coral reef ecosystem were undertaken. Settling particulate samples were collected by sediment traps deployed in the Zhubi reef lagoon and its outer areas. Other samples include plankton, coral frame, algae, seawater and surface sediments.
Coral reef ecosystems have a high gross productivity while their net productivity is low. The rapid cycling and efficient recycling of carbon are very important in the lagoon. The results indicate that inorganic carbon is the dominant form in the reef ecosystem and is controlled mainly by the balance of carbonate solution and calcification. Cycling of organic carbon in the lagoon is very fast and efficient. More than 93.6% (X1 deployed station) and 95.83% (X2 deployed station) particulate organic carbon (POC) can be released into water before it sinks into sediment. In situ regeneration supplies the most carbon required by the reef communities. Vertical fluxes of carbon in the lagoon are higher than the adjacent atolls. Besides, the release rate of biotic detritus POC is about 99%.
Particulate absorption and organism utilization control the distributions of abiogenic carbon in particulate, organisms and sediments. Element analysis indicated that sinking particulates in the lagoon mainly came from biogenic detritus while part of particulates came from resuspended sediments in the seaward slope of the reef. However, the transfer mechanism of carbon is similar. Hydrodynamics and bioenrichment with feeding processes are probably the key control factors.
Carbon budgets are not always in equilibrium in the coral reef lagoon; it is probable that high production in reef communities is supported by the cooperation of several strategies. The maintenance of high productivity in Nansha coral reef ecosystem depends on both high efficient cycling and stable supply, which can be described by a“simulated driftnet”model and a“Suspension fishing”model, respectively. Suspension fishing strategy can restore the excessive consumed primary productivity. The organism and its metabolic products play an important role in carbon continuous input process. For coral reef protection more attention should be paid to water circumstance and biotic multiformity.
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| Key words: Carbon cycling, Coral reef ecosystem, Nansha |
