Arbuscular mycorrhizal fungal establishment in cordgrasses (Sporobolus spp.) at restored and natural Bay of Fundy salt marshes

Abstract

Salt marshes are dynamic ecosystems recognized for their environmental contributions in mitigating climate change. As
known carbon sinks, they are highly productive ecosystems supporting numerous biotic assemblages, including fungal communities. Arbuscular mycorrhizal fungi (AMF) are endomycorrhizal symbionts that form associations with approximately 80% of plant roots, aiding plants in nutrient and water acquisition. Some AMF species can survive halophytic conditions and are known from roots of keystone cordgrass species in the genus Sporobolus (formerly Spartina). We analyzed AMF establishment in three cordgrass species, each species from low, middle, or high marsh elevations, at 10 salt marshes in the upper Bay of Fundy, Nova Scotia. Arbuscular mycorrhizal fungal establishment significantly varied by salt marsh grass species and was highly variable among sites. Sediment phosphorus and sodium had no significant impact on AMF establishment, whereas sediment nitrogen did influence their establishment in addition to other variables (i.e., tidal inundation). The highest % AMF establishment occurred in cordgrasses from middle and high marsh elevations at older restored and reference (natural) sites. We found the highest AMF establishment (94%) at restored salt marshes in Prairie Cordgrass (Sporobolus michauxianus) roots. Given their underappreciated yet potentially critical roles in coastal ecosystems, the contributions of AMF warrant further investigation to understand their ecological significance in supporting coastal salt marsh resilience.