School of Environment & Science and Australian Rivers Institute - Nathan Campus, Griffith University, 170 Kessels Road, Brisbane, Nathan, Queensland, 4111, Australia.
Laboratory of Phycology, Department of Botany, Center for Biological Sciences, Federal University of Santa Catarina, 88040-970, Florianópolis, SC, Brazil.
Sci Rep. 2019 Feb 13;9(1):1932. doi: 10.1038/s41598-018-35670-3.
The ultimate effect that ocean acidification (OA) and warming will have on the physiology of calcifying algae is still largely uncertain. Responses depend on the complex interactions between seawater chemistry, global/local stressors and species-specific physiologies. There is a significant gap regarding the effect that metabolic interactions between coexisting species may have on local seawater chemistry and the concurrent effect of OA. Here, we manipulated CO and temperature to evaluate the physiological responses of two common photoautotrophs from shallow tropical marine coastal ecosystems in Brazil: the calcifying alga Halimeda cuneata, and the seagrass Halodule wrightii. We tested whether or not seagrass presence can influence the calcification rate of a widespread and abundant species of Halimeda under OA and warming. Our results demonstrate that under elevated CO, the high photosynthetic rates of H. wrightii contribute to raise H. cuneata calcification more than two-fold and thus we suggest that H. cuneata populations coexisting with H. wrightii may have a higher resilience to OA conditions. This conclusion supports the more general hypothesis that, in coastal and shallow reef environments, the metabolic interactions between calcifying and non-calcifying organisms are instrumental in providing refuge against OA effects and increasing the resilience of the more OA-susceptible species.
海洋酸化（OA）和变暖对钙化藻类生理学的最终影响在很大程度上仍然不确定。响应取决于海水化学、全球/局部胁迫和物种特异性生理学之间的复杂相互作用。共存物种之间代谢相互作用可能对局部海水化学产生的影响以及 OA 的并发影响方面存在重大差距。在这里，我们操纵 CO 和温度，以评估来自巴西热带浅海沿海生态系统的两种常见光自养生物的生理反应：钙化藻类 Halimeda cuneata 和海草 Halodule wrightii。我们测试了海草的存在是否会影响 OA 和变暖条件下广泛存在且丰富的 Halimeda 物种的钙化率。我们的结果表明，在升高的 CO 下，H. wrightii 的高光合速率有助于将 H. cuneata 的钙化率提高两倍以上，因此我们认为与 H. wrightii 共存的 H. cuneata 种群可能对 OA 条件具有更高的恢复力。这一结论支持更普遍的假设，即在沿海和浅礁环境中，钙化和非钙化生物之间的代谢相互作用对于提供抵御 OA 影响的避难所和增加更易受 OA 影响的物种的恢复力至关重要。
