Coastal and Ocean Processes, Virginia Institute of Marine Science, William & Mary, Gloucester Point, Virginia, USA.
Ecosystem Health, Virginia Institute of Marine Science, William & Mary, Gloucester Point, Virginia, USA.
Ecology. 2024 Sep;105(9):e4385. doi: 10.1002/ecy.4385. Epub 2024 Jul 19.
Consumers can directly (e.g., consumption) and indirectly (e.g., trophic cascades) influence carbon cycling in blue carbon ecosystems. Previous work found that large grazers have nuanced effects on carbon stocks, yet, small, bioturbating-grazers, which remove plant biomass and alter sediment properties, remain an understudied driver of carbon cycling. We used field-derived and remote sensing data to quantify how the purple marsh crab, Sesarma reticulatum, influenced carbon stocks, flux, and recovery in salt marshes. Sesarma caused a 40%-70% loss in carbon stocks as fronts propagated inland (i.e., ungrazed to recovered transition), with front migration rates accelerating over time. Despite latitudinal differences, front migration rate had no effect on carbon stocks, flux, or time to replacement. When we included Sesarma disturbance in carbon flux calculations, we found it may take 5-100 years for marshes to replace lost carbon, if at all. Combined, we show that small grazers cause a net loss in carbon stocks as they move through the landscape, and irrespective of migration rate, these grazer-driven impacts persist for decades. This work showcases the significant role of consumers in carbon storage and flux, challenging the classic paradigm of plant-sediment feedbacks as the primary ecogeomorphic driver of carbon cycling in blue carbon ecosystems.
消费者可以直接（例如，消费）和间接（例如，营养级联）影响蓝碳生态系统中的碳循环。以前的研究发现，大型食草动物对碳储量有细微的影响，但小型、生物扰动食草动物会去除植物生物量并改变沉积物特性，它们仍然是碳循环的一个研究不足的驱动因素。我们使用实地数据和遥感数据来量化紫蟹 Sesarma reticulatum 如何影响盐沼中的碳储量、通量和恢复。Sesarma 导致碳储量减少 40%-70%，因为前沿向内陆传播（即未放牧到恢复过渡），前沿迁移率随时间加速。尽管存在纬度差异，但前沿迁移率对碳储量、通量或替代时间没有影响。当我们将 Sesarma 的干扰纳入碳通量计算中时，我们发现如果有的话，盐沼可能需要 5-100 年的时间才能取代失去的碳。总之，我们表明，当小型食草动物在景观中移动时，它们会导致碳储量净损失，并且无论迁移率如何，这些食草动物驱动的影响都会持续数十年。这项工作展示了消费者在碳储存和通量中的重要作用，挑战了植物-沉积物反馈作为蓝碳生态系统碳循环主要生态地貌驱动因素的经典范式。
