Nihal Guennouni: Understanding ecosystem dynamics through cannibal crabs
As a seventh grader growing up in Reston, Virginia, Nihal Guennouni M.S. ’25 developed an early fascination with the ocean, fueled by a love of animals and a steady stream of National Geographic magazines. That interest deepened when she conducted an interview for a school project with a researcher at the Smithsonian Environmental Research Center (SERC)—an experience that planted the first seed of a career in marine science.
Though she stayed on the biology track through high school and initially began her undergraduate studies at George Mason University, Guennouni eventually transferred to Christopher Newport University (CNU) to pursue a curriculum focused on environmental science. It was there that her academic path became clear. Research with a CNU professor on oyster reef restoration and living shorelines drew her into the world of applied science—science that directly supports coastal resources management and community resilience.
After considering various paths, including medical school and environmental law, Guennouni ultimately chose to pursue an M.S. at William & Mary’s Batten School & VIMS. A lecture on environmental justice further solidified her desire to use research as a tool for societal benefit.
“I wanted to do science that eventually helps people,” Guennouni explained. “The Batten School & VIMS offered a chance to engage in applied science with real-world management and policy implications.”
Guennouni’s master’s thesis focused on an essential Chesapeake Bay species, the blue crab. Specifically, her research explored how cannibalism—a common trait among blue crabs—affects the spread of a parasitic disease and overall population dynamics. Working under academic advisor Professors Romuald Lipcius and committee member Professor Jeff Shields, Guennouni examined whether high rates of cannibalism could naturally limit disease transmission by removing infected crabs from the population.
Her findings ran counter to long-held assumptions. Contrary to expectations, infected crabs were less likely to be eaten, particularly when provided with structured habitat like seagrass. Their lethargy and limited movement appeared to reduce their visibility to predators, while healthier, more active crabs became frequent targets.
“The sick ones weren’t being eaten more, they were actually surviving longer,” said Guennouni.
The research was part of a broader National Science Foundation-funded project (NSF-EID 2207343) examining disease dynamics in blue crabs, with components ranging from ecological modeling to classroom outreach. Guennouni contributed both in the lab and in classrooms. As part of the Virginia Scientists & Educators Alliance (VA SEA) program, she designed a seventh-grade lesson plan based on her thesis work—introducing students to concepts of cannibalism and population control through an interactive game of predator-prey tag.
In addition to her thesis work and outreach, Guennouni immersed herself in the tight-knit community at the Batten School of Coastal & Marine Sciences & VIMS. “I have a problem where I don’t say no,” she laughed, reflecting on the many projects and collaborations she joined.
However, the desire to be involved in and learn new things is part of the wisdom that she would share with others following a similar path.
“Marine science is a huge field, and it can be overwhelming trying to figure out what you want to do,” said Guennouni. “My advice is to take advantage of opportunities as they come. Your ability to apply the components of your research is going to be more important than what you specifically studied, and it allows you to home in on the things you love.”
In her next chapter, Guennouni will be applying her knowledge as a marine scientist with the South Carolina Department of Natural Resources. Her time at the Batten School & VIMS also reshaped how she sees the environment.
“Everything in the ocean plays a role,” Guennouni said. “Even something that seems small can have massive implications for fisheries and management. The more I’ve learned, the more connected I feel to the Bay, to the ocean, to everything.”