Does epilithic biofilm community structure affect the mayfly microbiome?

Epilithic biofilm communities are influenced by abiotic and biotic forces such as flow conditions and invertebrate grazing, respectively. However, there is very little understood about how biofilm community successional characteristics affect grazer feeding preference in stream ecosystems. Epilithic biofilms were grown on unglazed porcelain tiles under ambient and modified flow treatment conditions in a third order stream of southwest of Ohio. The influence of modified flow (increased turbulence) on biofilm community succession was characterized at 7, 14, 21, and 28 days. At each stage of growth, these biofilm communities were then subjected to mayfly (Ephemeroptera: Heptageniidae) grazing in laboratory microcosms, and the gut microbiome was evaluated for community structure shifts after feeding on different biofilm communities. Modified flow was associated with increased biofilm primary production and biomass at 21d and there were substantial changes in community structure described using ARISA and 454 pyrosequencing. Biofilm communities at later stages of growth were differentially grazed by the mayflies, with significant biofilm reduction in those grown under modified flow after 21d. There were also notable shifts in the mayfly gut microbiome depending on the flow conditions and biofilm successional state. These results provide a better understanding of how abiotic conditions mediate the grazing activity and mayfly gut microbiome in aquatic ecosystems.