两种蔷薇珊瑚骨骼微结构观察及钙化过程分析

摘要

Montiporais the second species-rich scleractinian genus that is widely distributed in the Indo-Pacific Ocean. Montipora digitata andMontipora fragilis, two species of branchingMontipora, from the South China Sea were selected in this study, and its skeletal microstructures and calcification processes were observed and analyzed using Scanning Electron Microscopy (SEM) combined with Energy Dispersive Spectrometer (EDS). The results showed that the two species of Montipora skeletal basic elements were substantially the same (including calice, septum, theca, dissepiment, etc.), but there were many differences in details. Coenosteum surface ofM. digitata was glabrous and recticular formation with shorter spines (about 40μm) and each calices (about 1 mm) were separated by big interval. The septa of the first cycle was poorly developed except that the shape of its direct septum was sheet. In addition, teeth along the margin of septa developed well and had flat shape. The coenosteum surface of M. fragiliswas tuberculate and recticular formation with many small spines (about 100μm) and irregular nodular ridge between the calices. Compared withM. digitata, the first-cycle septa ofM. fragilis had degenerated teeth. Main ingredients of the two kinds of coral skeletons were aragonite crystals, with most being tufted-crystals and a few being pebble-crystals. EDS analysis showed that the components of calcium carbonate from the skeleton were not directly generated, but formed in the following four processes: 1) the calcium was concentrated to develop calcium point; 2) calcium combined with carbon and oxygen, and the content of carbon was higher than that of oxygen; 3) aragonite crystals tended to look regular, and the content of carbon decreased and that of oxygen increased; and 4) a lot of aragonite crystals gathered into sclerodermite in orderly arrangement to form mature skeleton.%蔷薇珊瑚属是印度—太平洋地区第二大造礁石珊瑚属,本研究选取两种分枝状蔷薇珊瑚——指状蔷薇珊瑚Montipora digitata与脆蔷薇珊瑚Montipora fragilis,利用扫描电子显微镜和能谱仪观察分析其骨骼微结构和钙化过程。结果表明,两种蔷薇珊瑚骨骼基本组成结构(包括珊瑚杯、隔片、体壁、鳞板等)大体相同,但也存在诸多细节差异。指状蔷薇珊瑚共骨为平滑型网状,表面有较短的小刺(长约40μm),珊瑚杯之间间隔较大(约1mm),第一轮隔片除直接隔片大而呈薄片状外,其他隔片发育不完整,隔片刺较发达呈扁平狭板状。脆蔷薇珊瑚共骨为瘤突型网状,表面有众多的小刺(长约100μm),珊瑚杯之间有隆起的脊,第一轮隔片退化成短刺状。脆蔷薇珊瑚体壁上的小孔比指状蔷薇珊瑚的大。蔷薇珊瑚骨骼主要成分为文石晶体,多为簇状,少数为鹅卵石状。能谱分析表明,珊瑚碳酸钙骨骼并非直接生成,而是经历以下4个过程：1)钙的富集,形成钙点；2)钙结合碳与氧,此时碳多氧少；3)文石晶体趋于规则,碳元素减少,氧元素增多；4)大量的文石晶体聚集成羽簇,有序地排列形成成熟的骨骼。