Temperate kelp forests contribute significantly to marine primary productivity and fuel many benthic and pelagic food chains. A large proportion of biomass is exported from kelp forests as detritus into recipient marine ecosystems, potentially contributing to Blue Carbon sequestration. The degradation of this organic material is slow and recent research has revealed the preservation of photosynthetic functions over time. However, the physiological correlates of detrital breakdown in Laminaria spp. have not yet been studied. The warming climate threatens to reshuffle the species composition of kelp forests and perturb the dynamics of these highly productive ecosystems. The present study compares the physiological response of degrading detritus from two competing North East Atlantic species; the native Boreal Laminaria hyperborea and the thermally tolerant Boreal-Lusitanian L. ochroleuca. Detrital fragment degradation was measured by a mesocosm experiment across a gradient of spectral attenuation (a proxy for depth) to investigate the changes in physiological performance under different environmental conditions. Degradation of fragments was quantified over 108 days by measuring the biomass, production and respiration (by respirometry) and efficiency of Photosystem II (by PAM fluorometry). Data indicated that whilst degrading, the photosynthetic performance of the species responded differently to simulated depths, but fragments of both species continued to produce oxygen for up to 56 days and sustained positive net primary production. This study reveals the potential for ostensibly detrital kelp to contribute to Blue Carbon fixation through sustained primary production which should be factored into Blue Carbon management. Furthermore, the physiological response of kelp detritus is likely dependent upon the range of habitats to which it is exported. In the context of climate change, shifts in species composition of kelp forests and their detritus are likely to have wide-reaching effects upon the cycling of organic matter in benthic ecosystems.

温带海带森林对海洋初级生产力做出了重大贡献，并为许多底栖和中上层食物链提供了燃料。很大一部分生物质作为碎屑从海带森林出口到接收者海洋生态系统中，可能有助于蓝碳固存。这种有机材料的降解速度很慢，最近的研究表明，随着时间的推移，光合作用功能得以保存。然而，海带属碎屑分解的生理相关性。尚未研究。气候变暖可能会重新调整海带森林的物种组成，并扰乱这些高产生态系统的动态。本研究比较了两个东北大西洋竞争物种降解碎屑的生理反应；原生的北方海带 (Boreal Laminaria hyperborea)和耐热的北方-卢西塔尼亚L. ochroleuca 。通过光谱衰减梯度（深度的代表）的中宇宙实验测量碎屑碎片降解，以研究不同环境条件下生理性能的变化。通过测量生物量、产量和呼吸作用（通过呼吸测定法）以及光系统 II 的效率（通过 PAM 荧光测定法），对 108 天内的碎片降解进行了量化。数据表明，在退化过程中，该物种的光合性能对模拟深度的反应不同，但这两个物种的碎片在长达 56 天的时间里持续产生氧气，并维持正净初级生产力。这项研究揭示了表面上碎屑海带通过持续的初级生产促进蓝碳固定的潜力，这应该纳入蓝碳管理。 此外，海带碎屑的生理反应可能取决于其出口的栖息地范围。在气候变化的背景下，海带森林及其碎屑物种组成的变化可能对底栖生态系统中有机物的循环产生广泛影响。