DNA-Based Detection and Patterns of Larval Settlement of the Corallivorous Crown-of-Thorns Sea Star (Acanthaster sp.)

219 larval settlement collectors were deployed on the Great Barrier Reef during 4 sampling periods between October 2016 and February 2020.

Deployments were approx. 2.5 months in duration, coinciding with the COTS summer reproduction and spawning season

All larval settlement collectors were deployed at three sampling locations in northern (near Lizard Island and Cairns) and central GBR (near Townsville), at three different depths (4-6m, 7-9m and 10-12m) and at three sites per reef.

Larval settlement collectors were constructed using 2 leaf baskets ¿lled with about 60–70 aquarium ¿lter Ovi-Flow bio balls. During deployment, each collector was secured to the substrate and allowed to float approx. 1m above the substrate.

All larval settlement collectors were deployed at sites with relatively steep reef slopes, de-¿ned by a high cover of coral rubble encrusted with coralline algae, which is where COTS juveniles are typically observed.

Following retrieval, each apparatus was processed to remove all sample material (see Doll et al. (2021) for more details). DNA extraction allowed for genetic analysis to explore spatial and temporal settlement patterns.

2016年10月至2020年2月的4个采样周期内，研究人员在大堡礁（Great Barrier Reef, GBR）共布设219个幼体附着收集器。单次布设周期约为2.5个月，与棘冠海星（Crown-of-Thorns Starfish, COTS）的夏季繁殖及产卵期高度重合。所有幼体附着收集器均布设至大堡礁北部（蜥蜴岛与凯恩斯附近）及中部（汤斯维尔附近）的3个采样区域，每个礁体设置3个采样位点；布设深度分为3组：4~6米、7~9米及10~12米。幼体附着收集器由2个叶片采样篮（leaf baskets）组装而成，内部装填约60~70个水族过滤用Ovi-Flow生物球（Ovi-Flow bio balls）。布设阶段，每个收集器均固定于底质之上，并悬浮于底质上方约1米处。所有幼体附着收集器均布设至礁坡较陡的点位，该类点位以覆盖有珊瑚藻结壳的珊瑚砾石覆盖率高为特征，而这也是棘冠海星幼体的典型观测生境。完成采样回收后，对每个装置进行处理以提取全部样本（详细操作流程参见Doll等（2021）的研究）。通过DNA提取开展遗传分析，以探究幼体附着的空间与时间分布模式。