Hawai'i Institute of Marine Biology, School of Ocean & Earth Sciences & Technology, University of Hawai'i at Mānoa, Moku o Lóe, Kānéohe, Hawai'i, USA.
Environmental Science and Monitoring, The Red Sea Development Company, Riyadh, Saudi Arabia.
PeerJ. 2022 Jul 18;10:e13653. doi: 10.7717/peerj.13653. eCollection 2022.
The global decline of coral reefs has driven considerable interest in active coral restoration. Despite their importance and dominance on mature reefs, relatively few coral restoration projects use slower growth forms like massive and encrusting coral species. Micro-fragmentation can increase coral cover by orders of magnitude faster than natural growth, which now allows cultivation of slow growing massive forms and shows promise and flexibility for active reef restoration. However, the major causes of variation in growth and survival of outplanted colonies remain poorly understood. Here, we report simple outplanting assays to aid in active reef restoration of slower growing species and increase the likelihood of restoration success. We used two different micro-fragmentation assays. Pyramid assays were used to examine variation associated with fragment size (ranging from ≈1-9 cm), nursery residence time (for both and nurseries), and 2D . 3D measurements of growth. Block assays were used to examine spatial variation among individual performance at outplanting sites in the field. We found 2D and 3D measurements correlated well, so measured survivorship and growth using top-down planar images for two of the main Hawaiian reef building corals, the plating and the massive . Pyramid assays housed and outplanted from the nursery showed no effect of residence time or size on overall survivorship or growth for either species. Results from the nursery, however, varied by species, with again showing no effect of nursery residence time or size on survivorship or growth. In contrast, nursery culture resulted in improved survivorship of small fragments, but net growth showed a weak positive effect of nursery time for medium fragments. Small fragments still suffered higher mortality than either medium or large fragments. Due to their lower mortality, medium fragments (≈3 cm) appear to be the best compromise between growth and survivorship for outplanting. Likewise, given weak positive gains relative to the investment, our results suggest that it could be more cost-effective to simply outplant medium fragments as soon as possible, without intermediate culture in a nursery. Furthermore, the block assay revealed significant differences in survivorship and growth among sites for individuals of both species, emphasizing the importance of considering spatial variation in coral survival and growth following outplanting. These results highlight the value of using short-term micro-fragmentation assays prior to outplanting to assess size, and location specific performance, optimizing the efficiency of active reef restoration activities and maximizing the probability of success for active coral restoration projects.
全球范围内珊瑚礁的衰退促使人们对积极的珊瑚修复产生了浓厚的兴趣。尽管在成熟的珊瑚礁中，块状珊瑚和丛生珊瑚等生长速度较慢的珊瑚种类具有重要性和优势，但相对较少的珊瑚修复项目使用这些珊瑚种类。微碎片技术可以使珊瑚覆盖面积在数量级上比自然生长快得多，这使得缓慢生长的块状珊瑚得以培育，并为积极的珊瑚礁修复提供了灵活性和潜力。然而，外植珊瑚的生长和存活率变化的主要原因仍知之甚少。在这里，我们报告了简单的外植实验，以帮助生长速度较慢的珊瑚种类进行积极的珊瑚礁修复，并提高修复成功的可能性。我们使用了两种不同的微碎片实验方法。金字塔实验用于研究与碎片大小（约 1-9 厘米）、苗圃停留时间（和苗圃）以及 2D 和 3D 生长测量相关的变化。块实验用于研究野外外植地点个体表现的空间变化。我们发现 2D 和 3D 测量结果相关性很好，因此对于夏威夷的两种主要造礁珊瑚，板状珊瑚和块状珊瑚，我们使用自上而下的平面图像来测量存活率和生长。从苗圃中放置和外植的金字塔实验结果表明，对于这两个物种，停留时间或大小对整体存活率或生长都没有影响。然而，来自苗圃的结果因物种而异，对于 ，苗圃停留时间或大小对存活率或生长都没有影响。相比之下，苗圃培养提高了小碎片的存活率，但对于中等大小的碎片，净生长显示出与苗圃时间的微弱正相关。小碎片的死亡率仍然高于中等或大碎片。由于死亡率较低，中等大小的碎片（约 3 厘米）在外植时似乎是生长和存活率之间的最佳折衷。同样，鉴于相对于投资的微弱正收益，我们的结果表明，对于外植，最简单、最具成本效益的方法可能是尽快外植中等大小的碎片，而无需在苗圃中进行中间培养。此外，块实验显示了两种珊瑚的个体在不同地点存活率和生长的显著差异，强调了在珊瑚外植后考虑珊瑚存活和生长的空间变化的重要性。这些结果突出了在进行外植之前使用短期微碎片实验来评估大小和特定位置性能的价值，从而优化积极的珊瑚礁修复活动的效率，并最大程度地提高积极的珊瑚修复项目成功的可能性。
