Jacob Allgeier was always drawn to the water. After he earned his Bachelor of Science degree, he studied salmon in Alaska. He then went to Africa and South America and “became obsessed with the Amazon.”
A friend and research mentor invited him to work with him in The Bahamas—a proposition that would ultimately change the trajectory of Allgeier’s career in conservation work. On Abaco Island in the northern Bahamas, he set up residence between a mangrove swamp and the ocean, sleeping in a hammock and living out of his car. He got into a routine of trekking two miles along the beach to a mouth of a creek where he’d catch fish and cook his meals on an open fire.
The hammock, the ocean, and especially the fish: It all drew him in. “That’s when I knew I wanted to continue working and studying here. The water had excitement and newness. You can’t see much in jungle waters,” he says. “This water, though, you could see everything happening under the surface.”
Today, Allgeier is an assistant professor of ecology and evolutionary biology at LSA. He brings his passion for conservation and personal stories from the Caribbean to the classroom, teaching Coastal Ecology and Sustainability. His goal: To provide a sense of hope and optimism for preserving coastal ecosystems while improving the livelihood of coastal organisms by putting ecological theory to the test.
“Coastal organisms include mangroves, fish, and even humans,” he says. “There’s an increasing need for food security in coastal societies, and I hope my work can help achieve that.”
So, what work is that, exactly?
Fish excretions. Yes, that’s fish pee. Could it improve food security in the Caribbean? Allgeier thinks so, and it might even help slow global warming.
Allgeier studies how fish behavior, and the variations of movement among different species, affect ecosystem function. When he began his work on Abaco Island, he and his team radio-tracked 33 gray snappers and 25 cubera snappers. They found that these two fish types spent most of their time swimming and foraging for food, increasing their metabolism. This resulted in more nutrient excretion.
Once Allgeier’s team understood how fish moved and their ability to transport nutrients, they began to further explore fish urine—and manipulating the location of those nutrients—and the growth of primary producers, or seagrass.
“Working with artificial reefs allowed us to test the effect of fish pee because of the way artificial reefs mimic patch reefs and function as an experimental model that can be manipulated,” Allgeier says.
This work would allow Allgeier to better understand the benefits of artificial reefs, their ability to promote ecosystem health, and their relationship with aquatic organisms.
Over the past 13 years, he and local teams glued together thousands of cinder blocks to create over 100 artificial reefs in seagrass beds, which led to the finding that more nutrients in the water leads to the plants that are exposed to that fertilizer growing more, providing more food at the base of the food web.
The evidence was clear: the reefs attracted fish, sustaining a rich diversity of fish that, when aggregated, recycled nutrients faster.
“Recycling nutrients” is science-speak for swimming around and peeing a lot. Areas with high rates of chemicals cycling between organisms and the environment are called “biogeochemical hotspots,” and Allgeier’s research between 2013 and 2017 showed that fish urine provides among the largest sources of nutrients to coral reefs, including nitrogen and phosphorous.
“Fish will pee no matter what, so if we can focus those nutrients somewhere, it can become a fertilizer that helps seagrass and algae grow—the ecosystem’s primary food source,” he says.
In short: More fish aggregation means more fish urine in a particular area; more fish urine means bigger plants; bigger plants lead to more food for invertebrates—which means more food for fish.
The promising results of artificial reefs on Abaco Island inspired Allgeier to expand this work in Haiti, where local fishers have to go out farther and deeper for their food because of the diminishing fish population close to shore.
“Haiti is heavily overfished, and some of our artificial reefs there have higher densities of fish than I would bet most fishers younger than 30 have ever seen before. The responses from local fishers to the densities on these artificial reefs has blown my mind,” he says.
The benefits from Allgeier’s work go beyond the potential to increase fisheries, though.
When these plants are fertilized by the fish pee, they grow faster and take in more carbon from the atmosphere and shunt it into the sediment. Carbon is one of the greatest contributors to global warming, so increasing the storage of carbon in the oceans is an important mechanism for mitigating climate change.
Allgeier emphasizes that his work is not that of an outsider swooping in and making decisions for local people. He has worked directly with fishers to construct and study artificial reefs, including holding community meetings to increase interest and awareness of conservation strategies in the area, with a long-term goal of increasing sustainability in coastal ecosystems.
“Once you commit to working with communities, taking time to engage them is inherently part of the job,” he says. He adds that he spends a lot of his time with the fishers, discussing future projects or results from their ongoing efforts in the area. He shows videos and photos of the project, and they ask questions and offer suggestions that help direct the next steps.
Since 2019, thanks to a five-year grant from the Packard Foundation, Allgeier has been using a radio-tracking system to study the feeding behaviors and excretion patterns of hundreds of fish in an area where he’s built several artificial reefs.
His team is creating deliverables for governments and practitioners like a seagrass carbon storage map. The map, which will cover the entire Caribbean, presents a strong case for the value of artificial reefs because of their ability to sequester a primary facilitator of global warming.
“I think there’s potential for us to scale the construction of artificial reefs up to regional levels. I think that’s actually possible,” he says. “If I could just scale up this research in the one area I worked in, helping put more food on people’s tables, that would be amazing. But my aspirations are to keep broadening the impact of this work.”
Allgeier is also building collaborations to work with fishing communities and artificial reefs in the Dominican Republic.
“I love my job because I get to see new places and meet amazing people. A primary goal is to provide education and conduct research that promotes conservation in one of most degraded ecological systems in the world,” he adds. “The need for conservation is urgent, and we need great ideas rooted in science. Fortunately, I see a lot of hope with fish.”
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