Scripps Institution of Oceanography, University of California San Diego, San Diego, CA, United States of America.
Department of Marine Sciences, University of Puerto Rico Mayagüez, Mayagüez, Puerto Rico.
PLoS One. 2024 Oct 23;19(10):e0312263. doi: 10.1371/journal.pone.0312263. eCollection 2024.
Coral reefs are facing threats from a variety of global change stressors, including ocean warming, acidification, and deoxygenation. It has been hypothesized that growing corals near primary producers such as macroalgae or seagrass may help to ameliorate acidification and deoxygenation stress, however few studies have explored this effect in situ. Here, we investigated differences in coral growth rates across a natural gradient in seawater temperature, pH, and dissolved oxygen (DO) variability in a nearshore seagrass bed on Dongsha Atoll, Taiwan, South China Sea. We observed strong spatial gradients in temperature (5°C), pH (0.29 pH units), and DO (129 μmol O2 kg-1) across the 1-kilometer wide seagrass bed. Similarly, diel variability recorded by an autonomous sensor in the shallow seagrass measured diel ranges in temperature, pH, and DO of up to 2.6°C, 0.55, and 204 μmol O2 kg-1, respectively. Skeletal cores collected from 15 massive Porites corals growing in the seagrass bed at 4 sites revealed no significant differences in coral calcification rates between sites along the gradients. However, significant differences in skeletal extension rate and density suggest that the dynamic temperature, pH, and/or DO variability may have influenced these properties. The lack of differences in coral growth between sites may be because favorable calcification conditions during the day (high temperature, pH, and DO) were proportionally balanced by unfavorable conditions during the night (low temperature, pH, and DO). Alternatively, other factors were simply more important in controlling coral calcification and/or corals were acclimated to the prevailing conditions at each site.
珊瑚礁正面临着各种全球性变化压力源的威胁，包括海洋变暖、酸化和缺氧。有人假设，在大型藻类或海草等初级生产者附近生长的珊瑚可能有助于缓解酸化和缺氧的压力，但很少有研究在现场探索这种影响。在这里，我们在南海东沙环礁的近岸海草床中，调查了海水温度、pH 值和溶解氧 (DO) 变异性的自然梯度下珊瑚生长率的差异。我们观察到海草床宽 1 公里范围内温度（5°C）、pH 值（0.29 pH 单位）和 DO（129 μmol O2 kg-1）的空间梯度很强。同样，浅水海草中自主传感器记录的昼夜变化也测量了温度、pH 值和 DO 的昼夜变化范围，最高可达 2.6°C、0.55 和 204 μmol O2 kg-1。在海草床中生长的 15 个巨石珊瑚的骨骼核心在 4 个地点采集，结果表明，沿着梯度的各个地点之间珊瑚钙化率没有显著差异。然而，骨骼延伸率和密度的显著差异表明，动态温度、pH 值和/或 DO 变异性可能会影响这些特性。站点之间珊瑚生长没有差异的原因可能是白天（高温、高 pH 值和高 DO）有利于钙化的条件与夜间（低温、低 pH 值和低 DO）不利的条件成比例地平衡。或者，其他因素在控制珊瑚钙化方面更为重要，或者珊瑚已经适应了每个地点的流行条件。
