University of Applied Sciences Van Hall Larenstein, Leeuwarden, The Netherlands.
Marine Animal Ecology group, Wageningen University and Research, Wageningen, The Netherlands.
PeerJ. 2024 Apr 30;12:e17291. doi: 10.7717/peerj.17291. eCollection 2024.
The mass mortality event of the herbivorous sea urchin in 1983-1984 has been a major contributor to the diminished resilience of coral reefs throughout the Caribbean. The reduction in grazing pressure resulted in algae proliferation, which inhibited coral recruitment after disturbances such as disease, hurricanes, pollution and climatic change induced marine heat waves. Natural recovery of after the 1983-1984 die-off has been slow. However, the few locations with recovered populations exhibit signs of improvement in coral reef health, prompting interest in restoration. Current restoration strategies include translocation of wild individuals, the restocking of juveniles that are either cultured from gametes or collected as settlers and head-started in a nursery, and assisted natural recovery by providing suitable settlement substrate. Both the collection of wild settlers and assisted natural recovery necessitate an understanding of the local, spatiotemporal trends in settlement. In this study, which was carried out on the Dutch Caribbean Island of Saba, artificial turf settlement collectors were deployed at nine locations around the island and monitored from June 2019 till July 2020 (13 months). The primary objective was to identify trends in larval settlement in space and time, to be able to optimize restoration efforts. Additionally, the small size of Saba allowed us to deploy settlement collectors around the island and compare settlement between windward and leeward sides. Our study showed that on Saba, settlement peaked in June and July, following similar seasonal trends observed around other islands in the Northeastern Caribbean. By far the most settlement occurred at the leeward side of the island, suggesting that hydrodynamic forces entrained larvae in the lee of Saba and/or calmer waters facilitated settlement. Limited settlement occurred on the more exposed windward locations. The identified high settlement locations are candidates for settler collection and restoration attempts. Continued monitoring of settlement, especially in light of the 2022 die-off, holds significance as it can provide insights into the potential of natural recovery.
1983-1984 年食草性海胆的大规模死亡事件是加勒比海整个地区珊瑚礁恢复力减弱的主要原因。由于放牧压力的减少，藻类大量繁殖，这抑制了珊瑚在疾病、飓风、污染和气候变化引起的海洋热浪等干扰后的繁殖。1983-1984 年大量死亡事件后，自然恢复速度缓慢。然而，少数恢复种群的地方显示出珊瑚礁健康状况改善的迹象，这引发了人们对恢复的兴趣。目前的恢复策略包括野生个体的移植、从配子培养或作为定居者收集的幼体的再放养，以及通过提供合适的定居基质来促进自然恢复。野生定居者的收集和自然恢复的辅助都需要了解定居的本地、时空趋势。在这项在荷属加勒比岛屿萨巴进行的研究中，人工草皮定居收集器被部署在岛屿周围的九个地点，并从 2019 年 6 月监测到 2020 年 7 月（13 个月）。主要目标是确定空间和时间上幼虫定居的趋势，以便能够优化恢复工作。此外，萨巴岛的面积较小，允许我们在岛屿周围部署定居收集器，并比较迎风侧和背风侧的定居情况。我们的研究表明，在萨巴，幼虫定居在 6 月和 7 月达到高峰，这与在东北加勒比其他岛屿观察到的类似季节性趋势一致。到目前为止，在岛屿的背风侧发生的定居最多，这表明萨巴岛下风处的水动力迫使幼虫进入背风区，或更平静的水域有利于定居。在更暴露的迎风位置，定居的情况有限。确定的高定居点是定居者收集和恢复尝试的候选地点。继续监测幼虫定居情况，特别是考虑到 2022 年的大量死亡事件，具有重要意义，因为它可以提供有关自然恢复潜力的见解。
