Assessing the variability and vulnerability of carbon function in coastal soft sediment ecosystems to inform protection.

Coastal soft sediment ecosystems can sequester and process large quantities of carbon, making these environments important in mitigating the impacts of climate change. However, demersal fishing methods can resuspend sediment, releasing CO2, and in the longer term change the physical, biological, and biogeochemical characteristics of the seafloor. Within the global response to climate change, there is a need for tools to support the identification of sites within our coastal zones that can maximize carbon storage and where marine protection will be most beneficial for both blue carbon budgets and biodiversity recovery. We assess multiple aspects of carbon cycling in coastal soft sediment environments to explore the drivers of function and their vulnerability to seafloor disturbance. This information is interpreted to demonstrate how it can support decision-making for enhancing blue carbon and marine protection for climate change mitigation. We found carbon cycle functionality is driven across multiple gradients, and sites with large infauna were more vulnerable to resuspension-induced CO2 release. The results demonstrate that by accounting for environmental variability and complexity in marine protection, we have the opportunity to enhance multiple aspects of carbon cycling, protect biodiversity, and manage the vulnerability of sites to resuspension-induced CO2 release.