Organisms in the Chesapeake Bay face rapid changes of salinity, water temperature, and dissolved oxygen levels in the summer months due to seasonally increased volumes of hypoxic water. We know that these environmental changes produce a large variation in microbiomes collected from the water column. However, we do not know the extent to which they alter microbiomes within host species with distinct life histories and differing salinity tolerances. Two organisms with habitats in Chesapeake Bay that tolerate salinity variability through osmoregulation are the American Blue Crab (Callinectes sapidus) and the Eastern Oyster (Crassostrea virginica). Additionally, these organisms are extremely important resources to the economy of Maryland. A few studies suggest that oyster microbiomes vary across individuals exposed to the same environmental conditions. However, we hypothesize that this may not apply to other species.
To test this, we used two species with different life histories: a sessile species (the Eastern Oyster, Crassostrea virginica), and a horizontally migratory species (the American blue crab, Callinectes sapidus). Each of these species will have their gill microbiomes undergo 16S rRNA amplicon sequencing to discover potential endosymbionts. We will examine whether the gill microbial communities extracted from the same species will be similar when samples were collected close to each other and become more dissimilar when their hosts were collected further away from each other. We expect to see a more randomized microbiome across oysters; however, we anticipate seeing a more similarities amongst gill microbiomes from the American Blue Crab since these organisms have more control over which environments they inhabit. In so far as American Blue Crabs and Eastern Oysters do not select their microbiome, we would expect to see similar gill microbiomes from hosts living in similar environmental conditions. Additionally, we anticipate dissolved oxygen to be a major factor that contributes to gill microbiome changes seen between samples extracted from the same species but in separate locations. We are currently analyzing sequence data to see if our data follows these anticipated results.