Halimeda growth on the Great Barrier Reef

Growth of the two most common Halimeda species (H. copiosa and H. opuntia) was studied at 4 sites on Davies Reef over 6 tagging periods between February 1981 and February 1982. Comparative data was collected from Myrmidon Reef for one tagging period (November 1981 to January 1982).A total of 1685 branch tips were tagged over the period of a year during visits to the reef at approximately 2-month intervals. New growth was recorded by detailed drawings mid-way and at the end of the period. If growth was too complex to record in the field, those samples were collected and taken back to the laboratory; new batches were tagged as replacements. The laboratory samples were photocopied, dried and weighed, and the total surface area measured with a Licor LI-3000 area meter.Variables recorded were: days, number of samples, time of year (Feb/Mar, Apr/May, Jun/Aug, Aug/Oct, Oct/Dec, Dec/Feb). Halimeda community habitat variables were: hole, bommie, leeward slope, windward slope.Rates were calculated for number of new segments per day. Rates of production were calculated in two ways based on (1) the number of branch tips per unit biomass and the rate of new segment production; and (2) the rate of loss of tagged branches in conjunction with rates of new segment production. Rates of contribution of Halimeda debris to sediment composition were also calculated. To quantify the growth of Halimeda on the central Great Barrier Reef. Supplements a study of Halimeda on reefs (of which Davies is one) across the Great Barrier Reef, see separate metadata record.

针对两种最常见的仙掌藻属（Halimeda）物种——H. copiosa与H. opuntia——的生长情况，研究人员于1981年2月至1982年2月间，在戴维斯礁（Davies Reef）的4个采样点开展了为期6个标记周期的观测研究。同时于1981年11月至1982年1月的1个标记周期内，从默米顿礁（Myrmidon Reef）采集了对比数据。本研究以约2个月为间隔开展礁区实地考察，全年累计标记了1685个藻枝尖端。研究人员通过中期与末期的详细绘图记录新生长量；若野外无法完整记录复杂的生长情况，则采集对应样本带回实验室开展后续分析，并补充标记新的藻枝尖端作为替换。实验室样本经影印、干燥称重后，采用Licor LI-3000型面积仪测定其总表面积。本次研究记录的变量包括：观测天数、样本数量、采样时段（2-3月、4-5月、6-8月、8-10月、10-12月、12-2月）。仙掌藻群落的生境变量涵盖：洞穴、礁丘、背风坡、迎风坡。研究人员计算了每日新生藻节的生成速率。生长速率通过两种方式测算：其一基于单位生物量对应的藻枝尖端数量与新生藻节生成速率；其二结合标记藻枝的脱落速率与新生藻节生成速率进行综合计算。此外还测算出仙掌藻碎屑对沉积物组成的贡献速率。本研究的核心目标为量化大堡礁中部区域仙掌藻的生长状况。本研究为大堡礁全礁区仙掌藻相关研究的补充项目（戴维斯礁为该研究的一处采样礁体），完整元数据请查阅独立元数据记录。