International Journal of Marine Science, 2024, Vol.14, No.5, 321-331 http://www.aquapublisher.com/index.php/ijms 327 opportunities for predators to access coral fragments (Rogers and Miller, 2020). The absence of bite marks and predator species other than Drupelia spp. is probably due to the choice of the experimental area, distant approximately 678 meters from the house reef, displaying a lower coralivorous species abundance. Survival rates for Acropora aspera, Acropora muricata, and Montipora digitata were approximately 86%, 80%, and 90%, respectively, after 6 months, with higher mortality observed in the initial 2~4 months followed by stabilization. The results suggest that while survival rates were not significantly affected by nursery design or depth, the initial period is critical for coral establishment and survival. During the recent bleaching event we observed that shallower depths, such as ⁓ 2 meters, were associated with higher mortality rates. Specifically, Anantara’s nursery at ⁓2 meters experienced a 50% mortality rate (except for Montipora digitata), whereas corals grown at ⁓5 meters had only a 20% mortality rate (personal observation). While shallower depths generally promote faster growth and higher survival rates under normal conditions (Kuffner and Toth, 2012), they also expose corals to greater temperature fluctuations during heat stress events (McClanahan et al., 2004; Hughes et al., 2012). This highlights the importance of selecting nursery depths with consideration for potential thermal anomalies and/or bleaching events. Rope-based nurseries, as demonstrated in our study, offer notable advantages including reduced predation and increased ecological volume. They reduce predation rates and contribute to a more favorable microhabitat for coral fragments (Rogers and Miller, 2020). An additional advantage of rope nurseries is their mobility. This characteristic is increasingly important in the context of risings sea temperature and frequent bleaching events. The ability to relocate entire ropes or, on a larger scale, entire nurseries, to different depths or areas allow for adaptive management strategies, potentially improving coral survival rates during thermal stress events. By integrating a comprehensive bleaching monitoring program, managers can optimize the placement of rope-based nurseries to mitigate the impacts of bleaching and other environmental stressors. From an economic perspective, the initial setup costs for rope-based nurseries are generally lower compared to metal table designs, making them a cost-effective option for initial implementation (Edmunds and Elahi, 2007). In terms of maintenance, rope nurseries require relatively minimal upkeep. Regular maintenance primarily involves cleaning the ropes to remove algae, competing invertebrates and fouling organisms and periodically lifting the ropes as coral colonies grow and increase in weight. These tasks are less demanding compared to the extensive maintenance often required for metal table designs, which can suffer from issues like rusting and structural degradation (Baker and Vize, 2015). The metal staples used in the rope-based nurseries, typically last between 8~10 years before needing replacement, reflecting their durability (personal observation). Outplanting from rope-based nurseries is also straightforward. Once the coral colonies have reached maturity, they can be outplanted individually using several methods such as epoxy, cement, or nails. Alternatively, entire ropes can be relocated and outplanted together. In such cases, the rope is secured to the substrate using natural materials or additional nails, facilitating the establishment of the coral colonies in their new environment (Harrison and Wallace, 2012). This flexibility in outplanting methods adds to the practicality of rope-based nurseries, making them a versatile tool for coral restoration. Despite the challenges, large-scale coral restoration using rope-based nurseries has the potential to deliver substantial ecological and economic benefits. Healthy coral reefs support vital ecosystem services, including fisheries, tourism, and coastal protection. The economic feasibility of these nurseries is supported by their contributions to reef health and the associated benefits to local economies. Demonstrating the effectiveness of these nurseries through pilot projects and securing funding from governmental, non-governmental, and private sectors will be critical for scaling up and sustaining these efforts. This study also considered the use of Montipora digitata, a species known for its high growth rates and greater resistance to environmental stress compared to other Acroporidae species. Montipora digitata is particularly suitable for restoration projects due to its robust nature and rapid colonization capabilities (Gomez et al., 2011). This species has been reported to withstand varying environmental conditions better than more sensitive species
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