Coral reefs in the southern Persian/Arabian Gulf have become increasingly degraded in the past two decades, mainly due to recurrent mass coral bleaching events. The recovery of these reefs will be largely contingent upon the arrival and settlement of coral larvae and their post settlement growth and survival. Spatial and temporal patterns of coral settlement were quantified on 10 sites spanning >350 km of the southern Gulf using settlement tiles for two years when consecutive bleaching events occurred. Coral settlement was highly seasonal, with peak settlement occurring in summer each year (>95% of spat), with the remainder of settlement in autumn. Coral settlement was >2-fold greater in the first year (928 spat) compared to the second year (397 spat) representing overall settlement densities of 95 m−2 yr−1 versus 40 m−2 yr−1. The dramatic declines in larval settlement between years suggests bleaching-related impacts on fecundity occurred during the gametogenic cycle late in the first year, as well as impaired survivorship of larvae and/or spat during the second year when severe bleaching coincided with the peak settlement period. Poritids and merulinids (‘others’) comprised 4% and 94% of the spat, respectively, while acroporids were virtually absent (1 recorded spat), suggesting the continued extirpation of this formerly dominant group and a continuing shift towards more stress-tolerant assemblages. Settlement rates in the southern Gulf are low in comparison to other marginal reef environments, and the bleaching-related suppression of settlement observed here suggests that larval supply is unlikely to be sufficient to support recovery of these increasingly degraded habitats. Given the increasing frequency of bleaching events in the southern Gulf the prognosis for the future of regional reefs is grim.

中文翻译：

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波斯湾/阿拉伯湾南部大规模白化后珊瑚沉降受到抑制

在过去的二十年里，波斯湾/阿拉伯湾南部的珊瑚礁日益退化，这主要是由于反复发生的大规模珊瑚白化事件。这些珊瑚礁的恢复在很大程度上取决于珊瑚幼虫的到达和定居以及它们定居后的生长和存活。当连续发生白化事件时，在两年内使用沉降瓦片在跨越 350 公里南部海湾的 10 个地点量化珊瑚沉降的时空模式。珊瑚沉降具有很强的季节性，沉降高峰发生在每年夏季（> 95% 的卵），其余的沉降在秋季。与第二年（397 个卵）相比，第一年（928 个卵）的珊瑚沉降大于 2 倍，代表总体沉降密度为 95 m-2 yr-1 与 40 m-2 yr-1。年间幼虫沉降的急剧下降表明，在第一年的配子周期后期发生了与白化相关的繁殖力影响，以及在第二年严重白化与沉降高峰期同时发生的幼虫和/或卵的存活率受损. Poritids 和 merulinids（“其他”）分别占卵的 4% 和 94%，而 acroporids 几乎不存在（记录了 1 次），这表明这个以前占主导地位的群体继续消失，并继续转向更具抗压性的组合. 与其他边缘珊瑚礁环境相比，南部海湾的定居率较低，这里观察到的与白化相关的沉降抑制表明，幼虫的供应不太可能足以支持这些日益退化的栖息地的恢复。鉴于海湾南部白化事件越来越频繁，区域珊瑚礁的未来前景不容乐观。