Simon F.S. Li Marine Science Laboratory, School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China.
Mar Environ Res. 2021 Jul;169:105352. doi: 10.1016/j.marenvres.2021.105352. Epub 2021 May 6.
Intertidal benthos link tertiary predators and primary producers in marine food webs as well as directly contribute to sediment CO emission. However, current methods for studying food sources of marine benthos are time-consuming and does not allow direct estimates on feeding regime-related (including different diets, active versus dormant) CO production. We examined the food sources of mangrove crabs and gastropods as well as their corresponding CO production using cavity-ring down spectroscopy to measure the δC-CO respiration for consumers, considering the effects of feeding regime, benthos taxa, and dominant feeding habit. Benthos taxa and feeding habit have significant impact on δC-CO respiration. Particularly, the δC-CO respiration for crabs (-23.9 ± 0.4‰) was significantly lower than that for gastropods (-17.5 ± 1.3‰). The δC-CO respiration for deposit-feeders was significantly higher than that for detritivores. There are significant differences in the amount of CO emitted and δC-CO respiration for crabs under different feeding regimes. The differences reflect diet-switching and fuel-switching by the crabs, i.e. 'you breathe what you eat'. Significant differences in CO production of crabs also exist between those feeding on microphytobenthos in the laboratory (0.13 ± 0.02 mmol g day) and on field collection (i.e. just collected from the field) (0.31 ± 0.03 mmol g day). CO production of crabs is strongly related to carapace width and length. The δC-CO respiration for mangrove crabs reflects their diet while crab-respired CO flux is related to crab size. These relationships enable partitioning the feeding habit and food sources of key benthos, and help incorporate their contribution into the overall sediment-atmosphere CO fluxes in mangrove forests.
潮间带底栖生物作为海洋食物网中的三级捕食者和初级生产者联系在一起，它们直接促进了沉积物 CO 的排放。然而，目前研究海洋底栖生物食物来源的方法既费时又不能直接估计与摄食模式相关的 CO 生成（包括不同的食物、活跃和休眠状态）。我们使用腔衰减全反射光谱法（cavity-ring down spectroscopy）来测量消费者的 δC-CO 呼吸，以检查红树林蟹和腹足动物的食物来源及其相应的 CO 生成，同时考虑摄食模式、底栖生物分类群和主要摄食习性的影响。底栖生物分类群和摄食习性对 δC-CO 呼吸有显著影响。特别是，蟹的 δC-CO 呼吸（-23.9 ± 0.4‰）明显低于腹足动物的 δC-CO 呼吸（-17.5 ± 1.3‰）。摄食沉积物的生物的 δC-CO 呼吸显著高于摄食碎屑的生物。在不同的摄食模式下，蟹的 CO 排放量和 δC-CO 呼吸有显著差异。这些差异反映了蟹的饮食转换和燃料转换，即“你呼吸你所吃的”。在实验室中以微藻为食的蟹（0.13 ± 0.02 mmol g day）和在野外采集的蟹（即刚从野外采集的蟹）（0.31 ± 0.03 mmol g day）之间，蟹的 CO 生成也存在显著差异。蟹的 CO 生成与甲壳宽度和长度密切相关。红树林蟹的 δC-CO 呼吸反映了它们的饮食，而蟹呼吸的 CO 通量与蟹的大小有关。这些关系使我们能够对关键底栖生物的摄食习性和食物来源进行划分，并有助于将它们的贡献纳入红树林生态系统的整体沉积物-大气 CO 通量中。
