Research in marine environments has shown that microbes can play an active role in degrading hydrocarbons, yet, very few studies have examined freshwater ecosystems. The Laurentian Great Lakes comprises over 90% of the surface freshwater in North America and concerns of crude impacts have recently increased due to a pipeline that crosses the Straits of Mackinac, the intersection of Lakes Michigan and Huron. To examine the impacts of crude on microbial communities in the Great Lakes, sediments and water collected from three different ecosystems (beach, coastal wetland, and profundal benthic sediments) were used in microcosm experiments amended with light synthetic crude. Ecosystems with greater diversity (wetland sediments) had a greater ability to resist community change (based on beta diversity) relative to lower diversity sites (sand). When microcosms were exposed to crude, all three ecosystems did show an enrichment of taxa (gammaproteobacterial and <i>Pseudomonas</i>) that have been previously known to degrade crude. Hydrocarbon degradation byproducts, such as methane and ethane, were also documented in the headspace of microcosms when exposed to crude, with coastal wetland sediments having the greatest concentrations. Taken together, these data document a high potential for microbial communities in sites with greater diversity (such as wetlands) to degrade crude, but a more limited ability for microbes in lower diversity sites, like beach sand. Current metagenomic analysis is underway to examine the genetic pathways that wetland communities could be using to degrade this crude.

Comparing the ability of microbial communities within Great Lake sediment ecosystems to degrade light synthetic crude

ACS Fall 2021

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