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In the spring of 2021, Shaily Rahman embarked from Cocodrie, Louisiana aboard the US�� bound for study sites near the Mississippi River Delta in the Gulf of Mexico. Her goal was a one-off trip to collect sediment samples over 2 days at sea. But just two weeks after her return, Hurricane Ida roared into the gulf with such force that it��.��

The storm devastated the Louisiana coastline. For Rahman and her students, it also created a scientific opening. Her sampling effort offered a pre-storm baseline that — if combined with subsequent data — could provide insight into how extreme weather affects the Gulf’s nutrient cycles.

Shaily Rahman takes a much-needed moment of respite aboard the RV Pelican, a boat in the . (Courtesy)

Rahman quickly secured funding through the National Science Foundation to return to the gulf. Since then, she has returned to the delta seven more times. This week, she is back again from another 10-day cruise aboard the Pelican with samples that will keep her lab busy for months.

Rahman’s focus is silicon, the second most abundant element in the Earth’s crust and an essential nutrient for life. Rivers like the Mississippi transport silicon into the ocean, where much of it is incorporated into the skeletons of single-celled plankton called diatoms. When the diatoms die, they sink to the ocean floor.��

While the amount of silicon and other nutrients entering the gulf via the Mississippi River is well-understood, Rahman’s research aims to discern what nutrients are released by the seabed.��

“How much of that nutrient flux is being recycled into the water column from the seabed and then available to algae?” Rahman posed.

Extreme weather, like Hurricane Ida, further complicates this question — and makes it more interesting. Heavy storms churn up the seabed and suspend sediment in the water. Rahman and her collaborators aim to discern if this disturbance may release a sudden pulse of nutrients before resettling.

��“It’s already a hard question to answer, and when you add in hurricanes and extreme weather — that makes it even harder,” she said.

These processes aren’t just theoretical, they have real-world tangible impacts. Diatoms, which rely on silicon, form the basis of the gulf’s marine food web. That food web, in turn, supports commercial fishing and tourism industries that��.�� Diatoms are also responsible for more than 15% of Earth’s oxygen production

The right balance of silicon, and other nutrients like nitrogen and phosphorus, can support a thriving marine ecosystem with plentiful fish. Yet, the wrong balance can lead to a proliferation of harmful algae that strip the gulf of oxygen leading to massive fish kills —��.

Rahman’s research questions are among many others aboard the Pelican. One researcher, for instance, is investigating the overlapping effects of the silicon cycle and the carbon cycle — research that could have major implications for future predictions of greenhouse gas warming.��

Rahman will also return to Boulder with a cooler full of preserved sediment samples for use in various graduate student research efforts. Collectively, these inquiries will help to demystify how chemicals move through the sediment, water, and air of the Gulf of Mexico. The results could help regional managers predict and mitigate negative outcomes.

“Developing a baseline is good for predictive models,” Rahman said. “Are the fish going to die, or is your food web going to be more productive?”

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