ABSTRACT
Seagrass meadows are declining globally at alarming rates due to multiple stressors. Efforts are underway to preserve and restore these valuable ecosystems. Several frameworks for seagrass restoration exist, and some restoration attempts are being made at scale; however, poor outcomes are widespread, suggesting our understanding of the processes that drive seagrass performance is still limited. We argue that plant-sediment interactions influence almost all components of restoration, yet they are poorly incorporated in restoration design and frameworks. We synthesise the current information on how belowground interactions influence seagrass health and identify which of these are amenable to manipulation and at what scale they could be employed to improve restoration strategies and decision-making frameworks. We identified three key, interdependent areas by which belowground interactions influence seagrass health and performance. Those three areas include how (1) sediment microbial communities control nutrient and chemical cycling for seagrass, (2) the response of seagrass to sediment processes may be influenced by their life history and genetics of seagrass species targeted for restoration and (3) other species may interact with sediments to promote or inhibit seagrass survivorship and growth. Decision-making frameworks should be extended to include belowground interactions because they are of fundamental concern for determining initial site suitability and affect subsequent decisions and planning for restoration. This, in turn, will improve restoration outcomes and community engagement, critical for the successful management of these endangered ecosystems.
