珊瑚礁区碳循环研究进展

珊瑚礁是海洋中生产力水平最高的生态系统之一,其碳循环受到有机碳代谢(光合作用/呼吸作用)和无机碳代谢(钙化/溶解)两大代谢过程的共同作用,过程十分复杂.珊瑚礁植物的光合作用保证了有机碳的有效补充,动物摄食及微生物降解等生物过程驱动了珊瑚礁区有机碳高效循环,只有不超过7％的有机碳进入沉积物,而向大洋区水平输出的有机碳通量变化幅度较大,主要受到水动力条件的影响.珊瑚礁区碳酸盐沉积(无机碳代谢)是全球碳酸盐库的重要组成部分,年累积量达到全球CaCO3年累积量的23%～26%,是影响大气CO2浓度的重要组成;珊瑚礁是大气CO2源或汇则取决于净有机生产力与净无机生产力的比值(ROI),当ROI <0.6时,珊瑚礁区是大气CO2的源,反之,则是大气CO2的汇.

Recent development in the research of carbon cycle in coral reef ecosystem

The carbon cycle in coral reefs, one of the most productive ecosystems in the ocean, includes the combination of organic carbon metabolism (photosynthesis/ respiration) and inorganic carbon metabolism (calcification / dissolution). The photosynthesis of plants in coral reefs converts CO_2 into organic carbon, making a useful supplement to organic carbon cycle. Because of the highly efficient organic carbon cycle facilitated by coral reef animals′ feeding activities and micro-biological degradation, there are no more than 7% of organic carbon being precipitated into sediment. While the horizontal flux of organic carbon transported into ocean is greatly controlled by hydrodynamic conditions and can vary widely. The carbonate precipitated during inorganic carbon metabolism on coral reefs is an important part of global carbonate reservoir, which contributes 23%-26% of global CaCO_3 accumulation and affects atmospheric CO_2 concentration. Net organic-to-inorganic carbon production ratio (ROI) is developed as a criterion in reflecting the sink/source behavior of CO_2 on coral reefs. When ROI is less than 0.6, the coral reef is the source of atmospheric CO_2, otherwise the coral reef acts as a sink of atmospheric CO_2. The recent work has established the preliminary understanding on the biogeochemical process of coral reef carbon cycle, thus the ongoing research will cover the mechanism of efficient organic carbon cycle of coral reefs, the function of coral reef organisms on carbon cycle, and the response of coral reef carbon cycle to climate change etc.