Enhancing Coral Survival on Deployment Devices With Microrefugia

This study examined the effects of microhabitat features on the survival of Acropora tenuis spat in a year-long experimental field deployment of two types of artificial settlement devices.

Fragments of mature gravid Acropora tenuis (Dana 1846) colonies were collected from Backnumbers Reef on the central mid shelf of the Great Barrier Reef ahead of coral spawning in Nov 2018. The corals were transported back to the Australian Institute of Marine Science National Sea Simmulator (SeaSim) facility and kept in temperature controlled outdoor aquaria. Egg-sperm bundles were collected during spawning from six colonies and cross-fertilized. Larvae were maintained in the culture tank until used in the experiment.

Two types of experimental settlement devices—lattice-grids and grooved-tiles—were designed and manufactured to test larval settlement choice and post-settlement survival. Prior to settlement, all experimental devices were conditioned in the SeaSim for approximately 4 weeks to develop a biofilm and recruit crustose coralline algae (CCA) for larval settlement induction.

Eight days after fertilization larvae were left to settle on the devices for 4 days. Images of the lattice-grids and grooved-tiles racks were taken 9 and 11 days after larval introduction (approx. 5-7 days after settlement).

The settlement devices were then deployed at Backnumbers Reef onto three replicate racks on a shallow, central mid-shelf reef of the Great Barrier Reef. Survival of A. tenuis recruits was tracked by assessment of in situ images, taken on SCUBA, of the upper- and under-sides of each device. Images were taken at 41, 95, 185, 246, and 311 days and then imaged again upon retrieval from the field on 16th December 2019 at the final time point of 376 days post settlement.

本研究通过两种人工附着装置的为期一年野外实验布设，探究了微生境特征对细枝鹿角珊瑚（Acropora tenuis）幼体存活率的影响。

2018年11月珊瑚产卵前，研究人员从大堡礁中部陆架区的巴克纳斯礁（Backnumbers Reef）采集成熟怀卵的细枝鹿角珊瑚（Acropora tenuis，Dana 1846）群落断枝。将珊瑚转运至澳大利亚海洋科学研究所国家海洋模拟设施（SeaSim），置于温控室外水族箱中暂养。于产卵期从6个珊瑚群落中收集精卵束，进行异体受精。幼虫在培养缸中培育至实验使用阶段。

研究人员设计并制备了两种实验附着装置——格状网格与带槽陶砖，用于测试幼虫的附着偏好与附着后存活率。附着实验开展前，所有装置均在SeaSim中驯化约4周，以形成生物膜并接种壳状珊瑚藻（CCA），用于诱导幼虫附着。

受精后8天，将幼虫放置于装置上进行4天的附着培养。幼虫投放后第9天与第11天（约附着后5-7天），分别对格状网格架与带槽陶砖架进行成像记录。

随后将附着装置部署至大堡礁中部陆架浅水区的巴克纳斯礁，布设3个重复架。通过水肺潜水获取各装置上下表面的原位图像，追踪细枝鹿角珊瑚招募体的存活情况。分别于附着后41、95、185、246和311天采集图像，并于2019年12月16日从野外回收装置时完成最后一次成像，此时为附着后376天的最终时间节点。