Estimation of photosynthesis and calcification rates at a fringing reef by accounting for diurnal variations and the zonation of coral reef communities on reef flat and slope: a case study for the Shiraho reef, Ishigaki Island, southwest Japan
Estimation of photosynthesis and calcification rates at a fringing reef by accounting for diurnal variations and the zonation of coral reef communities on reef flat and slope: a case study for the Shiraho reef, Ishigaki Island, southwest Japan
复制标题
DOI：
10.1007/s00338-008-0454-8
复制
发表时间：
2009-03
期刊：
影响因子：
3.5
通讯作者：
T. Nakamura;T. Nakamori
中科院分区：
文献类型：
--
作者：
T. Nakamura;T. Nakamori
在日本石垣岛白穗边缘礁上划分了7个珊瑚礁群落。净光合作用和钙化率是通过在10个地点的原位孵育来测量的，这些地点包括6个已定义的群落，它们占据了礁滩和斜坡上的大部分区域。总体而言，礁滩的净光合作用为正，但礁滩作为大气CO2的来源，因为测量到的钙化/光合作用比为2.5大于临界比1.67。礁坡的净光合作用为负。几乎所有来自礁滩的多余有机产品都将被排出到外礁，并被那里的群落消耗。因此，整个珊瑚礁系统的总净有机产量可能几乎为零，整个珊瑚礁系统也作为大气CO2的来源。礁坡珊瑚的净钙化率远低于分支珊瑚。前者的累积速率约为0.5 m kyr−1，后者的累积速率约为0.7 ~ 5 m kyr−1。因此，在全新世期间，礁坡珊瑚的生长速度不足以跟上或赶上海平面的上升。另一方面，分支珊瑚的生长速度足以跟上海平面的上升。因此，在全新世早期和现在的珊瑚礁群落之间的过渡是预期的。当珊瑚礁的生长与海平面上升保持同步时，分支珊瑚群落将占主导地位，珊瑚礁是由分支珊瑚框架构成的。然后，这个框架的外部被礁坡珊瑚覆盖和建造，形成了今天的珊瑚礁。
Seven coral reef communities were defined on Shiraho fringing reef, Ishigaki Island, Japan. Net photosynthesis and calcification rates were measured by in situ incubations at 10 sites that included six of the defined communities, and which occupied most of the area on the reef flat and slope. Net photosynthesis on the reef flat was positive overall, but the reef flat acts as a source for atmospheric CO2, because the measured calcification/photosynthesis ratio of 2.5 is greater than the critical ratio of 1.67. Net photosynthesis on the reef slope was negative. Almost all excess organic production from the reef flat is expected to be effused to the outer reef and consumed by the communities there. Therefore, the total net organic production of the whole reef system is probably almost zero and the whole reef system also acts as a source for atmospheric CO2. Net calcification rates of the reef slope corals were much lower than those of the branching corals. The accumulation rate of the former was approximately 0.5 m kyr−1and of the latter was ~0.7–5 m kyr−1. Consequently, reef slope corals could not grow fast enough to keep up with or catch up to rising sea levels during the Holocene. On the other hand, the branching corals grow fast enough to keep up with this rising sea level. Therefore, a transition between early Holocene and present-day reef communities is expected. Branching coral communities would have dominated while reef growth kept pace with sea level rise, and the reef was constructed with a branching coral framework. Then, the outside of this framework was covered and built up by reef slope corals and present-day reefs were constructed.