School of Biological Sciences and Aquatic Chemical Ecology Center, Georgia Institute of Technology, Atlanta, GA, United States of America.
Department of Biological Sciences, Institute of Environment, Florida International University, North Miami, FL, United States of America.
PLoS One. 2020 Aug 13;15(8):e0235465. doi: 10.1371/journal.pone.0235465. eCollection 2020.
As carbon dioxide (CO2) levels increase, coral reefs and other marine systems will be affected by the joint stressors of ocean acidification (OA) and warming. The effects of these two stressors on coral physiology are relatively well studied, but their impact on biotic interactions between corals are poorly understood. While coral-coral interactions are less common on modern reefs, it is important to document the nature of these interactions to better inform restoration strategies in the face of climate change. Using a mesocosm study, we evaluated whether the combined effects of ocean acidification and warming alter the competitive interactions between the common coral Porites astreoides and two other mounding corals (Montastraea cavernosa or Orbicella faveolata) common in the Caribbean. After 7 days of direct contact, P. astreoides suppressed the photosynthetic potential of M. cavernosa by 100% in areas of contact under both present (28.5°C and ~400 μatm pCO2) and predicted future (30.0°C and ~1000 μatm pCO2) conditions. In contrast, under present conditions M. cavernosa reduced the photosynthetic potential of P. astreoides by only 38% in areas of contact, while under future conditions reduction was 100%. A similar pattern occurred between P. astreoides and O. faveolata at day 7 post contact, but by day 14, each coral had reduced the photosynthetic potential of the other by 100% at the point of contact, and O. faveolata was generating larger lesions on P. astreoides than the reverse. In the absence of competition, OA and warming did not affect the photosynthetic potential of any coral. These results suggest that OA and warming can alter the severity of initial coral-coral interactions, with potential cascading effects due to corals serving as foundation species on coral reefs.
随着二氧化碳（CO2）水平的上升，珊瑚礁和其他海洋系统将受到海洋酸化（OA）和变暖的联合胁迫。这两个胁迫因素对珊瑚生理的影响已经得到了较为充分的研究，但它们对珊瑚之间生物相互作用的影响却知之甚少。虽然现代珊瑚礁上珊瑚之间的相互作用较少，但记录这些相互作用的性质对于在气候变化面前更好地为恢复策略提供信息是很重要的。通过一项中尺度实验研究，我们评估了海洋酸化和变暖的综合影响是否改变了常见珊瑚石珊瑚（Porites astreoides）和另外两种在加勒比地区常见的堆积珊瑚（Montastraea cavernosa 或 Orbicella faveolata）之间的竞争相互作用。在直接接触 7 天后，在目前（28.5°C 和400 μatm pCO2）和预测的未来（30.0°C 和1000 μatm pCO2）条件下，P. astreoides 在接触区域完全抑制了 M. cavernosa 的光合作用潜力 100%。相比之下，在目前的条件下，M. cavernosa 在接触区域仅降低了 P. astreoides 的光合作用潜力 38%，而在未来的条件下则降低了 100%。在接触后的第 7 天，P. astreoides 和 O. faveolata 之间也出现了类似的模式，但到第 14 天，每一种珊瑚都在接触点将另一种珊瑚的光合作用潜力降低到了 100%，而且 O. faveolata 在 P. astreoides 上产生的病变比相反的情况更大。在没有竞争的情况下，OA 和变暖不会影响任何珊瑚的光合作用潜力。这些结果表明，OA 和变暖可以改变初始珊瑚-珊瑚相互作用的严重程度，由于珊瑚是珊瑚礁的基础物种，因此可能会产生级联效应。
