Sorbonne Université, UPMC Université Paris VI, IFD-ED 129, Paris Cedex 05, France; Centre Scientifique de Monaco, Coral Ecophysiology Team, 8 Quai Antoine I(er), MC 98000, Monaco.
Centre Scientifique de Monaco, Coral Ecophysiology Team, 8 Quai Antoine I(er), MC 98000, Monaco.
Sci Total Environ. 2023 Feb 1;858(Pt 2):159944. doi: 10.1016/j.scitotenv.2022.159944. Epub 2022 Nov 7.
Phosphorus (P) is an essential but limiting nutrient for coral growth due to low concentrations of dissolved inorganic concentrations (DIP) in reef waters. P limitation is often exacerbated when concentrations of dissolved inorganic nitrogen (DIN) increase in the reef. To increase their access to phosphorus, corals can use organic P dissolved in seawater (DOP). They possess phosphatase enzymes that transform DOP into DIP, which can then be taken up by coral symbionts. Although the concentration of DOP in reef waters is much higher than DIP, the dependence of corals on this P source is still poorly understood, especially with different concentrations of DIN in seawater. As efforts to predict the future of corals increase, improved knowledge of the P requirements of corals living under different DIN concentrations may be key to predicting coral health. In this study, we investigated P content and phosphatase activities (PAs) in Stylophora pistillata maintained under nutrient starvation, long-term nitrogen enrichment (nitrate or ammonium at 2 μM) and short-term (few hours) nitrogen pulses. Results show that under nutrient depletion and ammonium-enriched conditions, a significant increase in PAs was observed compared to control conditions, with no change in the N:P ratio of the coral tissue. On the contrary, under nitrate enrichment, there was no increase in PAs compared to control conditions, but an increase in the N:P ratio of the coral tissue. These results suggest that under nitrate enrichment, corals were unable to increase their ability to rely on DOP and replenish their cellular P content. An increase in cellular N:P ratio is detrimental to coral health as it increases the susceptibility of coral bleaching under thermal stress. These results provide an overall view of the P requirements of corals exposed to different nutrient conditions and improve our understanding of the effects of nitrogen enrichment on corals.
磷（P）是珊瑚生长的必需但有限的营养物质，因为珊瑚礁水中的溶解无机磷（DIP）浓度较低。当珊瑚礁水中的溶解无机氮（DIN）浓度增加时，P 限制通常会加剧。为了增加对磷的获取，珊瑚可以利用溶解在海水中的有机磷（DOP）。它们拥有磷酸酶，可将 DOP 转化为 DIP，然后被珊瑚共生体吸收。尽管珊瑚礁水中的 DOP 浓度远高于 DIP，但珊瑚对这种磷源的依赖仍然知之甚少，尤其是在不同浓度的 DIN 存在的情况下。随着预测珊瑚未来的努力增加，更好地了解生活在不同 DIN 浓度下的珊瑚的磷需求可能是预测珊瑚健康的关键。在这项研究中，我们研究了在营养饥饿、长期氮富集（硝酸盐或铵盐 2 μM）和短期（数小时）氮脉冲下维持的石珊瑚（Stylophora pistillata）中的 P 含量和磷酸酶活性（PA）。结果表明，与对照条件相比，在营养耗尽和铵盐富集条件下，PA 显著增加，而珊瑚组织的 N:P 比值没有变化。相反，在硝酸盐富集下，与对照条件相比，PA 没有增加，但珊瑚组织的 N:P 比值增加。这些结果表明，在硝酸盐富集下，珊瑚无法增加依赖 DOP 的能力并补充细胞内的 P 含量。细胞 N:P 比值的增加对珊瑚健康有害，因为它会增加珊瑚在热胁迫下白化的易感性。这些结果提供了暴露于不同营养条件下的珊瑚的 P 需求的整体视图，并提高了我们对氮富集对珊瑚的影响的理解。
Zotero 插件