Changes in morphology and diet of the coral Stylophora pistillata along a depth gradient
Changes in morphology and diet of the coral Stylophora pistillata along a depth gradient
复制标题
DOI：
10.3354/meps07908
复制
发表时间：
2009-01-01
影响因子：
2.5
通讯作者：
Tchernov, Dan
中科院分区：
文献类型：
--
作者：
Einbinder, Shai;Mass, Tali;Tchernov, Dan
由于技术限制，热带珊瑚礁的光限制环境尚未得到深入研究。研究这片珊瑚礁对于理解珊瑚-藻类共生的生态和生理意义以及确定水下光场对其测深分布的边界至关重要。在本研究中，我们描述了 Stylophora pistillata 珊瑚群落的形态变化，并沿着其完整的测深分布跟踪其碳源（自养/异养行为）的变化。造血型珊瑚的生长形式必须在促进光合作用的最佳捕光表面与加强对浮游动物等营养丰富来源的利用的其他结构和/或机制之间进行折衷。这种结构调节受到物种特定的结构和生物学特征的限制。我们发现，大量分枝的 S. pistillata 菌落从高光环境下的亚球形形态转变为深度下的平面结构。宿主珊瑚组织的稳定碳同位素组成（δ C-13）从浅水中的 -15 ppm 变为深礁石中的 -23 ppm。后一个值表示稳定同位素组成等于或低于 -23 ppm 的碳源，或者宿主和藻类之间涉及同位素分馏 (epsilon) 的内部碳循环。 Delta C-13 值显示与形态性状显着相关，但在性状内发现了矛盾的趋势。异养的明显转变并不明显，因此，这表明内部循环和 Rubisco 活性是决定同位素组成的主要过程。
The light-limited environment of tropical coral reefs has not been intensively studied due to technical limitations. Studying this vast part of the coral reef is paramount to understanding the ecological and physiological significance of coral-algae symbiosis and defining the boundaries imposed on its bathymetric distribution by the underwater light field. In the present study we describe morphological changes in colonies of the coral Stylophora pistillata and track changes in its carbon sources (autotrophic/heterotrophic behavior) along its full bathymetric distribution. The growth form of hermatypic corals must compromise between an optimal light-trapping surface facilitating photosynthesis and other structures and/or mechanisms that enhance exploitation of nutrient-rich sources such as zooplankton. That architectural modulation is constrained within the species-specific structural and biological characteristics. We found that the profusely branched S. pistillata colonies shift between subspherical morphology at high-light environments to a planar structure at depth. The stable carbon isotopic composition (delta C-13) of the host coral tissue changed from a value of -15 parts per thousand in shallow water to -23 parts per thousand, at the deep reef. The latter value indicates either a carbon source with a stable isotope composition equal or below -23 parts per thousand or, alternatively, internal carbon cycling between host and algae that involves isotopic fractionation (epsilon). The delta C-13 values showed significant correlation to morphological traits, but contradicting trends were found within the traits. A clear shift to heterotrophy was not apparent, which, therefore, suggests that the internal cycling and Rubisco activity are the dominant processes determining isotopic composition.