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Salinity is an important factor in determining the distribution of aquatic organisms. Nevertheless, there are some species adapted to a wide range of osmotic conditions, including fish \cite{21444822}, insects \cite{25886355}, and plants \cite{Garrote_Moreno_2014}. Submerged aquatic vegetation (SAV) are plants that are rooted in the sediment and remain fully submerged most of the time. They are a polyphyletic assemblage restricted to shallow waters by light penetration. They posses several, convergent adaptations to life underwater, including the loss of a waxy cuticle, air cells that allow leaves to float, and specialized epidermal osmoregulartory cells \cite{Les_1997}. The presence of SAV is known to influence the structure, density, and metabolic activity of sediment microbial communities \cite{Regier_2012}\cite{Zhao_2013}\cite{Menon_2013}\cite{Meng_2015}, and there is some evidence that SAV species may have an effect on rhizosphere microbial community structure \cite{Gagnon_2007}\cite{Meng_2013}. Whether the microbial communities found in association with SAV (i.e., the SAV microbiome) play any role in plant adaptation to a fully aquatic lifestyle, and in particular, in plant adaptation to high salinity, is unknown.   The Chesapeake Bay is the largest estuary in the United States, fed by over 100 rivers and flowing into the Atlantic Ocean. One of these, the Potomac River has a salinity gradient that ranges from 0 to 12.5 ppt ppt,  and SAV in the Potomac River exhibit variation in their ability to thrive across this salinity gradient. For example, Ruppia maritima is known to survive in water ranging from fresh up to 70ppt 70 ppt  \cite{Kantrud_1991} (for reference, ocean salinity averages 30-35ppt). 30-35 ppt).  Other species are more restricted, like Vallisneria americana, which grows poorly at a salinity of 8 ppt, and does not tolerate 18 ppt \cite{Boustany_2009}. The James River also flows into the Chesapeake Bay, and offers the opportunity to study a second, parallel salinity gradient. In this study, we aimed to characterize the microbial communities associated with the SAV species found along a salinity gradient in both the Potomac and James Rivers. For this, we had the opportunity to join a field trip planned by our colleague (Andrew Whitehead) to sample killifish at 6 sites along each river. Unfortunatley, while killifish were abundant at all sites, SAVs proved to be more elusive, and in fact were never found at the sites along the James River. Therefore, we report here our findings for a total of 5 species of SAV, collected from 4 sites along the Potomac River.