Geochemical responses of scleractinian corals to nutrient stress
Geochemical responses of scleractinian corals to nutrient stress
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DOI：
10.1016/j.gca.2023.04.011
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发表时间：
2023-04
影响因子：
5
通讯作者：
C. Standish;T. B. Chalk;M. Saeed;F. Lei;M. C. Buckingham;C. D. ’. Angelo;J. Wiedenmann;G. Foster;C. Rollion-Bard
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文献类型：
--
作者：
C. Standish;T. B. Chalk;M. Saeed;F. Lei;M. C. Buckingham;C. D. ’. Angelo;J. Wiedenmann;G. Foster;C. Rollion-Bard
尽管许多珊瑚礁的营养平衡受到人为活动的干扰，但营养条件的变化对珊瑚地球化学指标的影响知之甚少。在这里，研究了热带珊瑚Acropora Polystoma和Porites地衣在培养条件下生长后对营养物质丰富和枯竭的地球化学响应，以评估营养物质对温度和珊瑚内部碳酸盐系统的传统地球化学指标的影响。在140日的时间里，珊瑚被暴露在四种不同的营养处理下：(1)充分处理，具有最佳水平的硝酸盐(∼4.5mμM)和磷酸盐(∼0.6mμM)，(2)营养耗竭处理，可忽略硝酸盐和磷酸盐，(3)高硝酸盐(∼73μM)和可忽略的磷酸盐处理，和(4)高磷酸盐处理(∼5.7mμM)和可忽略的硝酸盐。结果表明，到目前为止，营养物质在珊瑚骨骼元素(Li/Ca，B/Ca，Mg/Ca，Sr/Ca，Li/Mg)和同位素(δ11B)组成中的作用一直被低估，内部碳酸盐化学也受到影响。例如，与两种植物的充分处理相比，营养不平衡和耗竭处理中的镁/钙和锶/钙较低，而锂/镁较高。在不平衡的营养条件下养殖的珊瑚碳酸盐系统的破坏，最好的解释是细胞外钙化介质中溶解的无机碳通量的减少。营养物浓度的变化--或营养物失衡--可能对重建的海洋表面温度和海洋或钙化pH产生显著影响，重建的温度从−7°C到+52°C不等，δ11B派生的pH最高可达0.13pH单位。因此，在使用珊瑚骨骼档案生成环境的时间记录时，应考虑到人类造成的营养干扰的影响。
The impact of changing nutrient conditions on scleractinian coral-based geochemical proxies is poorly understood, despite the nutrient balance in many coral reefs being disturbed by anthropogenic activity. Here, the geochemical responses of tropical coralsAcropora polystomaandPorites lichento nutrient enrichment and depletion are examined following growth under cultured conditions, to assess the impact of nutrients on traditional geochemical proxies for both temperature and the coral internal carbonate system. The corals were exposed to four different nutrient treatments over a period of 140 days: (1) a replete treatment with optimal levels of nitrate (∼4.5 μM) and phosphate (∼0.6 μM), (2) a nutrient depleted treatment with negligible nitrate and phosphate, (3) a treatment with high nitrate (∼73 μM) and negligible phosphate, and (4) a treatment with high phosphate (∼5.7 μM) and negligible nitrate. Results suggest nutrients play a hitherto under-appreciated role in coral skeleton elemental (Li/Ca, B/Ca, Mg/Ca, Sr/Ca, Li/Mg) and isotopic (δ11B) composition, with the internal carbonate chemistry also impacted. For example, Mg/Ca and Sr/Ca are lower, and Li/Mg higher, in the nutrient imbalanced and deplete treatments compared to the replete treatment for both species. Disruption to the carbonate system in corals cultured under imbalanced nutrient conditions is best explained by a decrease in dissolved inorganic carbon flux to the extracellular calcifying medium. Variations in nutrient concentration — or nutrient imbalance — can have dramatic consequences on both reconstructed sea surface temperatures and ocean or calcification pH, with reconstructed temperatures varying from −7°C to +52 °C, and δ11B-derived pH by up to 0.13 pH units. The impact from anthropogenically-induced nutrient disturbances should therefore be considered when generating temporal records of environments using coral skeletal archives.