Sarah Gray, PhD, has dutifully worked on a funded research project since 2007 to study the impact of watershed development on coral reefs in St. John, U.S. Virgin Islands.
The research project, which casts a wide net on assessments, has enabled Gray, a USD Marine Science and Environmental Studies professor, to utilize more than a dozen USD students and to put their research skills to work.
Gray’s environmental sustainability project, annually funded by the National Oceanic and Atmospheric Administration (NOAA), has included a few undergraduates, but mostly students in USD’s Marine Science graduate program. The project gives them valuable, hands-on experience and data that gets published. In one instance, a student’s research helped nonprofit organizations in this tropical community reap nearly $3 million in stimulus funding to build and repair the watersheds and reduce the amount of sedimentation going in the coral reefs.
The latest student to get involved Gray’s project is Robert “Bobby” Harrington, a second-year Marine Science graduate student who arrived after earning his undergraduate degree in geology at the University of Maine. Prior to that, he served six years in the U.S. Navy.
Harrington’s passion for studying rocks and his interest in geochemistry fit Gray’s needs as other graduate students concluded their research in St. John.
“We don’t have a geology major (at USD) so I was really happy when Bobby came. He gives us a geologist capable of doing this important research,” Gray said.
Harrington showcased his work in poster form at last Thursday’s Graduate Research Day, titled “Ridge to Reef Assessment of Metal Concentration and Mineralogy in Rocks and Sediments on St. John, U.S. Virgin Islands.”
His work is tailored to Gray’s examination of sedimentation and how “development around the island has increased (land-derived) sedimentation in coastal bays with coral reefs.”
Harrington explained further: “Hydrothermally altered bedrock in the watersheds contributes metal-rich sediment to ephemeral streams and bays around St. John. To determine if land-based sedimentation is affecting sensitive benthic reef environments, we’ve compared the chemistry and mineralogy among bay sediment (reef and shore) and watershed sediment and bedrock.”
The geologist’s two visits to the research site were successful: “The objectives are to determine how the distribution of metal concentrations and mineralogy change as bedrock and sediment are eroded from the ridge and transported to reefs and how much land-derived metals are present at fringing reefs.”
Harrington used “X-ray fluorescence” to measure major and trace concentrations of rock and sediments. Mineralogy determination involved the analysis of 35 sediment and rock thin sections.
His data ultimately showed “major and trace elements that derive from (land-derived) sources are present at fringing reef sites in Coral Bay and Great Lameshur Bay.” It also showed “higher concentrations of terrestrial-derived metals are detected below developed watersheds compared to undeveloped.”
While his work on the project is not completed — his summer will mainly be spent on writing his research — Harrington has thrived on the experience and is proud of his contribution to something that will have a lasting impact.
“Geochemistry can be done anywhere, but I like finding and studying rocks and, at the same time, doing research in a beautiful place,” he said of St. John. “It’s been great, too, because what I really like about this project is we’re using science to make a change in the community. This is science that’s educating people, it’s helping them better understand how the environment is working.”
— Ryan T. Blystone