The Chesapeake Bay, the largest estuary in the continental United States, weaves its way south from Maryland, collecting waters from West Virginia, Delaware, DC, Pennsylvania and New York along the way. Like many major ecosystems and watersheds, the Chesapeake Bay is being substantially changed by ongoing environmental crises. Now, researchers from the Virginia Institute of Marine Science (VIMS) are using supercomputing power to understand these changes, lending insight into the Chesapeake Bay as well as changes in broader coastal waters.

Specifically, the researchers – led by Pierre St-Laurent, a research scientist at VIMS – simulated the effects of historical increases in fertilizer concentrations in the bay, as well as the effects of increasing carbon dioxide concentrations in the atmosphere, over a period of about a hundred years (from the early 1900s to the early 2000s). To run these simulations, the research team used the Comet supercomputer at the San Diego Supercomputer Center (SDSC). Comprising 1,944 Intel Haswell-based compute nodes and 72 Nvidia-based GPU nodes, Comet delivers 2.76 peak petaflops.

“Without Comet, we would have had to scale down our experiments drastically, affecting the scientific scope of the study and leaving important questions unanswered,” St-Laurent told SDSC’s Kimberly Mann Bruch in an interview. “Because our research spanned two periods of time covering the early 1900s to the early 2000s, our computational requirement vastly exceeded the resources available at our local research center, but they were well within the computing capacities at SDSC.”

The simulations found that those changes in emissions and fertilizers had effectively forced the estuary to develop stronger carbon sequestration abilities — a trend that they say is “likely to continue in the decades to come.” The concentrations of chemicals from fertilizers, on the other hand, they expect to wane in the wake of fading nitrogen-driven farming activity.

“Upon studying what happened during the last 100 years, we determined that the bay now absorbs slightly more carbon dioxide than it releases into the atmosphere,” St-Laurent said. “This result exemplifies the particularity of the continental U.S.’s largest estuary, but also may be indicative of the magnitude of the changes that are ongoing in coastal waters throughout the world.”

St-Laurent and his team are hopeful that their research – which was published in a recent issue of Biogeosciences – will help shed light on the challenges facing the Chesapeake Bay so that decision-makers can help preserve the environmentally and economically crucial watershed (and those like it).

“Our study provides valuable perspective to watershed managers as it compares the long-term impact of fertilizer usage with other global changes,” St-Laurent said. “Not only is the health of the Chesapeake Bay important for ecological reasons, but also for economic purposes as the seafood industry driven by these waters is estimated to contribute around two billion dollars in sales each year and approximately 40,000 jobs, according to the Chesapeake Bay Foundation.”