Marine Biological Association of the United Kingdom, The Laboratory, Citadel Hill, Plymouth, UK.
J Phycol. 2023 Jun;59(3):481-495. doi: 10.1111/jpy.13332. Epub 2023 Apr 11.
Coastal marine ecosystems are threatened by a range of anthropogenic stressors, operating at global, local, and temporal scales. We investigated the impact of marine heatwaves (MHWs) combined with decreased light availability over two seasons on the ecophysiological responses of three kelp species (Laminaria digitata, L. hyperborea, and L. ochroleuca). These species function as important habitat-forming foundation organisms in the northeast Atlantic and have distinct but overlapping latitudinal distributions and thermal niches. Under low-light conditions, summertime MHWs induced significant declines in biomass, blade surface area, and Fv/Fm values (a measure of photosynthetic efficiency) in the cool-water kelps L. digitata and L. hyperborea, albeit to varying degrees. Under high-light conditions, all species were largely resistant to simulated MHW activity. In springtime, MHWs had minimal impacts and in some cases promoted kelp performance, while reduced light availability resulted in lower growth rates. While some species were negatively affected by summer MHWs under low-light conditions (particularly L. digitata), they were generally resilient to MHWs under high-light conditions. As such, maintaining good environmental quality and water clarity may increase resilience of populations to summertime MHWs. Our study informs predictions of how habitat-forming foundation kelp species will be affected by interacting, concurrent stressors, typical of compound events that are intensifying under anthropogenic climate change.
沿海海洋生态系统受到一系列人为胁迫的威胁，这些胁迫作用于全球、地方和时间尺度。我们研究了海洋热浪（MHWs）与两个季节光照减少相结合对三种大型褐藻物种（Laminaria digitata、L. hyperborea 和 L. ochroleuca）的生态生理响应的影响。这些物种是东北大西洋重要的栖息地形成基础生物，具有不同但重叠的纬度分布和热生态位。在低光照条件下，夏季 MHWs 导致冷水种大型褐藻 L. digitata 和 L. hyperborea 的生物量、叶片表面积和 Fv/Fm 值（光合作用效率的衡量标准）显著下降，尽管下降程度不同。在高光条件下，所有物种在很大程度上都能抵抗模拟的 MHW 活动。在春季，MWHs 的影响很小，在某些情况下还促进了大型褐藻的表现，而光照减少导致生长速度下降。虽然一些物种在低光照条件下夏季 MHWs 受到负面影响（特别是 L. digitata），但它们在高光条件下通常对 MHWs 有很强的抵抗力。因此，保持良好的环境质量和水清晰度可能会提高种群对夏季 MHWs 的抵抗力。我们的研究为预测栖息地形成的基础大型褐藻物种将如何受到相互作用的并发胁迫的影响提供了信息，这些胁迫是在人为气候变化下加剧的复合事件的典型特征。
