Hawaii Institute of Marine Biology, University of Hawaii at Manoa, Kaneohe, Hawaii, United States.
PeerJ. 2022 Jul 14;10:e13707. doi: 10.7717/peerj.13707. eCollection 2022.
Terrestrial-based nutrient pollution has emerged as one of the most detrimental factors to coral health in many reef habitats. Recent studies have shown that excessive dissolved inorganic nutrients can reduce coral thermal tolerance thresholds and even exacerbate bleaching during thermal stress, yet the effects of minor nutrient enrichment under heat stress have not been extensively studied. In this study, , , and colonies under heated conditions (~30.5 °C) were exposed to low and balanced nitrogen and phosphorous concentrations over a 31-day heating period. Coral colonies were collected from Kāne'ohe Bay, O'ahu, which has a unique history of nutrient pollution, and held in mesocosms that allowed for environmental manipulation yet are also influenced by local field conditions. Principal findings included delays in the bleaching of nutrient-enriched heated colonies as compared to heated-only colonies, in addition to relatively greater calcification rates and lower proportions of early-stage paling. Species-specific outcomes were prevalent, with demonstrating no difference in calcification with enrichment under heat stress. By the end of the heating stage, however, many heated colonies were at least partially impacted by bleaching or mortality. Despite this, our findings suggest that low levels of balanced nutrient enrichment may serve as a mitigative force during thermal events. Further field-based studies will be required to assess these results in different reef habitats.
基于陆地的营养污染已成为许多珊瑚礁栖息地中对珊瑚健康最有害的因素之一。最近的研究表明，过量的溶解无机营养物会降低珊瑚的热耐受阈值，甚至在热胁迫期间加剧白化现象，但在热胁迫下，轻微的营养富集的影响尚未得到广泛研究。在这项研究中，在加热条件下（约 30.5°C），将 和 珊瑚虫暴露于低浓度和平衡的氮磷浓度下，为期 31 天的加热期。珊瑚虫从瓦胡岛的卡内奥赫湾收集，该地区具有独特的营养污染历史，并保存在中观生物培养箱中，这些培养箱可以进行环境操纵，但也受到当地现场条件的影响。主要发现包括与仅加热的珊瑚虫相比，营养丰富的加热珊瑚虫的白化延迟，以及相对较高的钙化率和较低的早期苍白比例。不同物种的结果普遍存在， 在热胁迫下，营养富集对其钙化没有影响。然而，到加热阶段结束时，许多加热的珊瑚虫至少部分受到白化或死亡的影响。尽管如此，我们的研究结果表明，低水平的平衡营养富集在热事件中可能是一种缓解因素。需要进一步的实地研究来评估这些结果在不同的珊瑚礁栖息地中的表现。
