Coastal Stressor Effects on Sediment and Salt Marsh Cordgrass (Spartina alterniflora) Root-Associated Microbiomes

Abstract

Coastal marshes provide ecological benefits such as processing upstream contaminants, protecting coastlines from high energy storm surges, and providing habitat for a multitude of species. Coastal marshes are dominated by only a small number of key species such as the marsh cordgrass Spartina alterniflora (also known as Sporobolus alterniflorus), and the establishment and productivity of this species is essential to successful coastal marsh restorations. However, human activities (e.g., drainage, development) and climate change (e.g., increased duration and frequency of storms, sea-level rise) have contributed to increased coastal marsh loss. Moreover, environmental conditions, sediment microbiome composition, and S. alterniflora growth all play a vital role in the restoration and maintenance of coastal marshes. Therefore, examining how chemical (e.g., sediment nutrients) factors relate to S. alterniflora root microbiome composition can inform future management approaches for enhancing marsh restoration efforts. This project examined the extent that environmental conditions and the resident sediment microbes influence S. alterniflora root-associated bacterial community composition. I hypothesize that S. alterniflora roots provide carbon resources for microbes and buffer root-associated microbes from dynamic environmental changes in coastal marshes. To test this hypothesis, I characterized microbiome composition of bulk and root-associated sediment microbiomes at three salt marsh locations and measured the effect of location and sample type on microbiome composition using permutational multivariate analysis. This work will serve as foundational knowledge for future studies promoting beneficial plant-microbe relationships in a coastal marsh restoration context.