Bathymetric adaptations of corals at Davies Reef, Great Barrier Reef: Light saturation

Corals were collected by scuba along 2 transects at Davies Reef in October 1980, and February, July and December 1981. Transect A-B ran from 1-17 m deep on the seaward margin of the reef flat. Transect C-D ran from 1-51 m deep on the seaward reef slope. Collection date, sea surface temperature, transect, depth and coral species were recorded.For the experiments, either a group of four 12 cm terminal branches of Acropora formosa or Acropora valenciennesi, or one 9 cm diameter colony of all other species were placed in a chamber and changes in dissolved oxygen content measured. Light measurements of photosynthetic photon flux density were in units of microEinsteins (400-700 nm) per square metre per second. Corals were incubated in the dark and light for periods of 20-30 min, arranged in order of increasing light intensity.The corals were frozen at the end of the experiment; chlorophylls and accessory pigments were extracted with 3 volumes of 20% tetrahydrofuran in methanol (v:v), separated and quantified by high performance liquid chromatography. Ten replicate coral samples were analysed for protein content. To establish:- whether photoadaptations occur in reef-building corals- whether photoadaptations occur as continuous gradients correlated to ambient light intensity- whether relationships between photoadaptations and ambinet light intensity can be mathematically described- whether corals from high/low light environments correspond to definitions of sun/shade plants Data analyses were part of a series of three papers addressing:1. Long-term growth responses (data not held by AIMS)2. Light saturation curves for photosynthesis and respiration3. UV-B absorbing compounds (see separate metadata record)

1980年10月及1981年2月、7月、12月，研究人员通过水肺潜水在戴维斯礁（Davies Reef）的2条样带上采集珊瑚样本。样带A-B布设于礁坪向海边缘，水深范围为1至17米；样带C-D布设于礁坡向海区域，水深范围为1至51米。本次采集记录了样本的采集日期、海表温度、样带编号、采样水深及珊瑚物种信息。

实验环节中，研究人员将4段12厘米长的鹿角珊瑚属（Acropora）顶枝（鹿角杯形珊瑚（Acropora formosa）或瓦氏鹿角珊瑚（Acropora valenciennesi））组成一组，或是选取其他所有珊瑚物种的1个直径9厘米的珊瑚群体，放置于密闭培养舱内，监测溶解氧含量的变化。光合光子通量密度的光照测量单位为每平方米每秒微爱因斯坦（400-700纳米波段）。珊瑚样本分别在黑暗与光照条件下培养20至30分钟，培养顺序按光照强度递增排布。

实验结束后，研究人员对珊瑚样本进行冷冻保存；采用3倍体积的甲醇-20%四氢呋喃混合液（体积比v:v）提取叶绿素及辅助色素，通过高效液相色谱（high performance liquid chromatography，HPLC）完成分离与定量分析。同时对10份重复珊瑚样本开展蛋白质含量测定。

本研究旨在验证四项科学问题：
1. 造礁珊瑚是否存在光适应现象；
2. 光适应是否以与环境光照强度相关的连续梯度形式存在；
3. 光适应与环境光照强度之间的关系能否通过数学方法进行描述；
4. 来自高/低光照环境的珊瑚是否符合阳生/阴生植物的定义。

本次数据分析隶属于三篇系列研究论文的工作内容，该三篇论文分别探讨：
1. 珊瑚长期生长响应（相关数据未由澳大利亚海洋科学研究所（Australian Institute of Marine Science，AIMS）持有）；
2. 光合作用与呼吸作用的光饱和曲线；
3. 紫外-B吸收化合物（详见独立元数据记录）。