Coralline algae are important components in a large variety of ecosystems. Among them, rhodoliths are a group of free-living coralline red algae that cover extensive coastal areas, from tropical to polar regions. In contrast to other ecosystem engineers, limited research efforts preclude our understanding of their physiology, underlying mechanisms, drivers and potential differences related to species under varying environments. In this study, we investigated the photosynthetic and calcification mechanisms of six Atlantic rhodolith species from different latitudes, as well as intra-specific differences in one species from four locations. Laboratory incubations under varying light levels provided simultaneous photosynthesis- and calcification-irradiance curves, allowing the assessment of inter- and intra-specific differences on the coupling between these two processes. Stable isotope analysis and specific inhibitor experiments were performed to characterize and compare carbon-concentrating mechanisms (CCMs), as well as the involvement of specific ion-transporters for calcification. Our findings showed significant differences in rhodolith physiological mechanisms that were partially driven by local environmental conditions (light, temperature). High variability was found in the coupling between photosynthesis and calcification, in CCM-strategies, and in the importance of specific ion transporters and enzymes involved in calcification. While calcification was strongly correlated with photosynthesis in all species, the strength of this link was species-specific. Calcification was also found to be reliant on photosynthesis- and light-independent processes. The latter showed a high plasticity in their expression among species, also influenced by the local environment. Overall, our findings demonstrate that (1) rhodolith calcification is a biologically-controlled process and (2) the mechanisms associated with photosynthesis and calcification display a large variability among species, suggesting potential differences not only in their individual, but also community responses to environmental changes, such as climate change.

珊瑚藻是多种生态系统中的重要组成部分。其中，rhodoliths是一组自由生活的珊瑚红藻，覆盖从热带到极地地区的广泛沿海地区。与其他生态系统工程师相比，有限的研究工作使我们无法理解它们的生理学、潜在机制、驱动因素以及在不同环境下与物种相关的潜在差异。在这项研究中，我们调查了来自不同纬度的六种大西洋石榴石物种的光合和钙化机制，以及来自四个地点的一个物种的种内差异。在不同光照水平下的实验室孵化提供了同时的光合作用和钙化辐照度曲线，允许评估这两个过程之间耦合的种间和种内差异。进行了稳定同位素分析和特异性抑制剂实验，以表征和比较碳浓缩机制 (CCM)，以及特定离子转运蛋白对钙化的参与。我们的研究结果表明，红石生理机制存在显着差异，这部分是由当地环境条件（光、温度）驱动的。在光合作用和钙化之间的耦合、CCM 策略以及参与钙化的特定离子转运蛋白和酶的重要性方面发现了高度可变性。虽然钙化与所有物种的光合作用密切相关，但这种联系的强度是物种特异性的。还发现钙化依赖于光合作用和光独立过程。后者在物种间的表达中表现出高度的可塑性，也受到当地环境的影响。总体而言，我们的研究结果表明（1）红石钙化是一个生物控制的过程，（2）与光合作用和钙化相关的机制在物种之间表现出很大的差异，这表明不仅个体存在潜在差异，而且群落对环境的反应也存在潜在差异。变化，例如气候变化。