Population turnover in the soft coral genera Sinularia and Sarcophyton on the Great Barrier Reef

Aspects of the life history of 2 common soft coral genera, Sinularia and Sarcophyton were investigated on 360 tagged colonies over 3.5 years. Measurements were carried out at 18 sites on 6 mid- (Centipede, Grub, Yankee) and outer-shelf reefs (Bowl, Coil, Dip) of the Great Barrier Reef and included rates of growth, colony fission, mortality, sublethal predation and algae infection. Photographic monitoring was carried out on [approximately] an additional 500 colonies from 16 genera.High numbers of the crown-of-thorns starfish, Acanthaster planci, had removed most of the hard coral cover on Grub, Yankee and Dip Reefs 5-8 years prior to the study, relieving soft corals from space competition with hard corals. The other 3 reefs in the study were little affected by Acanthaster planci and had high hard coral cover. Three sites were established on the windward sides of each reef at 10m depth, and percent hard and soft coral cover, current and wave exposure and slope angle were recorded. Turnover rates over the 40 month period were recorded as the proportion of colonies which: remained (R), disappeared (D), or appeared new (A). (The term, 'Colony Groups', was used for clusters of colonies in which the fate of individual colonies could not be followed due to high colony density or movement). To investigate life history characteristics which might allow the 2 genera to achieve such prominence, and to assess the role of space competition with hard corals in population dynamics. Soft coral species:Family Alcyoniidae (Cladiella, Lobophytum, Sarcophyton, Sinularia); Family Asterospiculariidae (Asterospicularia); Family Briareidae (Briareum); Family Clavulariidae (Clavularia); Family Isididae (Isis); Family Nephtheidae (Capnella, Dendronephthya, Lemnalia, Nephthya, Paralemnalia, Stereonephthya); Family Tubiporidae (Tubipora); Family Xeniidae (Efflatournaria, Xenia).

本研究针对2种常见软珊瑚属——指形软珊瑚属（Sinularia）与肉芝软珊瑚属（Sarcophyton）的生活史特征展开调查，历时3.5年，共追踪了360个经标记的珊瑚群体。
研究区域涵盖大堡礁的6座陆架中部礁（Centipede、Grub、Yankee）与陆架外缘礁（Bowl、Coil、Dip），共设置18个采样点，测量指标包括珊瑚生长速率、群体分裂率、死亡率、亚致死捕食压力及藻类感染情况。此外，研究还对16个珊瑚属的约500个珊瑚群体开展了摄影监测。

在研究开展前5至8年，Grub、Yankee与Dip礁海域曾爆发大量长棘海星（Acanthaster planci），导致绝大多数造礁硬珊瑚覆盖率丧失，从而解除了软珊瑚与硬珊瑚之间的空间竞争压力。本研究中其余3座礁体未受长棘海星显著影响，硬珊瑚覆盖率较高。

每座礁体的迎风侧10米水深处均设置3个采样点，记录了硬珊瑚与软珊瑚的盖度百分比、水流与波浪暴露程度以及斜坡坡度。研究记录了40个月周期内的珊瑚群体周转率，以三类群体的占比表征：持续存活（R）、消失（D）以及新增（A）。(注：当珊瑚群体密度过高或存在群体移动导致无法追踪单个群体的命运时，将此类集群称为"群体组（Colony Groups）")。

本研究旨在探究这两种软珊瑚属得以成为优势类群的生活史特征，并评估与硬珊瑚的空间竞争在其种群动态中的作用。

软珊瑚类群涵盖以下科属：
1. 软珊瑚科（Alcyoniidae）：克拉达软珊瑚属（Cladiella）、叶形软珊瑚属（Lobophytum）、肉芝软珊瑚属（Sarcophyton）、指形软珊瑚属（Sinularia）
2. 星针软珊瑚科（Asterospiculariidae）：星针软珊瑚属（Asterospicularia）
3. 柳珊瑚科（Briareidae）：柳珊瑚属（Briareum）
4. 棒形软珊瑚科（Clavulariidae）：棒形软珊瑚属（Clavularia）
5. 等轴珊瑚科（Isididae）：等轴珊瑚属（Isis）
6. 尖穗珊瑚科（Nephtheidae）：卡普纳拉珊瑚属（Capnella）、枝穗珊瑚属（Dendronephthya）、Lemnalia属（Lemnalia）、Nephthya属（Nephthya）、副Lemnalia属（Paralemnalia）、Stereonephthya属（Stereonephthya）
7. 笙珊瑚科（Tubiporidae）：笙珊瑚属（Tubipora）
8. 手星花珊瑚科（Xeniidae）：Efflatournaria属（Efflatournaria）、手星花珊瑚属（Xenia）