After spending some time in the office of AAAS member Bart De Stasio, Singleton Professor of Biological Sciences at Lawrence University, one understands the significance of the pictures of water fleas that surround him. His current research — which has global implications — depends on the dining habits of these tiny planktonic crustaceans.
As pelicans wheel in the distance, De Stasio describes his interest in the food web of Wisconsin's Green Bay. He explains that when zebra mussels, an invasive species, arrived there from the Black Sea via ships in the 1990s, they caused an increase in blue-green algae. Zebra mussels are hard-shelled creatures that cling in clumps, have no natural predators, and multiply rapidly. They eat phytoplankton but reject eating the naturally occurring blue-green algae in lakes and ponds. This leads to overpopulation of the algae in large "blooms." The mussels also release nutrients that encourage the growth of the algae.
At high levels, this algae (microcystins) is toxic and can be fatal to animals and even humans, causing liver damage. The algae can also affect the taste and odor of municipal water. However, De Stasio has identified a potential solution, a type of water flea that can eat the algae without succumbing to the toxins. Ironically, the water flea, Eurytemora, is itself an invasive species. He has two tanks of them in the lab: one tank eating algae, the other serving as a backup.
"My research last summer and this summer involves doing comparative studies of what's going on in Green Bay with what's going on in the Baltic Sea. Colleagues at Novia University in Finland are seeing the same thing we are. They're coming here this summer to do experiments with me in August when we typically get the worst algae blooms; and I went there with a student last summer to collaborate with them on this research."
De Stasio's love of aquatic biology took hold when he was an undergraduate student at Lawrence. "I came here to be a geneticist," he says, "but when I took a class on aquatic ecology, I fell in love with the field."
Uncertain whether he wanted to concentrate on marine biology or freshwater ecology, De Stasio did his graduate work in oceanography at the University of Rhode Island. But when his advisor left for Cornell, De Stasio followed, and subsequently focused on freshwater ecology. Still, it's handy having a background in both. "I can help students understand the common things that are going on in all aquatic systems," he says.
Every other year, he and another faculty member accompany 16 students to Grand Cayman Island in the Caribbean to study the coral reefs. "Similar things are going on in lakes as they are in the oceans, especially when you're talking about the interactions between animals and plants, and how they are responding to the physical and chemical environments. The examples are different, but the process is the same."
On their most recent trip, the group culled lionfish, an invasive species known for consuming large quantities of reef fish. "It's believed that the lionfish were escapees from an aquarium in Florida during a hurricane," says De Stasio. "They have spread throughout the whole Caribbean all the way up to Cape Cod. We became certified to cull lionfish from the reefs, learning how not to get stung in the process." As proof, his desk displays a Lionfish Culling License that is good indefinitely.
His passion for his work is evidenced by the items in his office, which include fossils of chain coral and honeycomb coral from Door County, Wisc.; a birthday card from a student with a drawing of a giant water flea on it; even a ceramic figure of a turtle made by his son when he was in third grade.
In addition to studying toxic algae, De Stasio's other current project involves monitoring for invasive species in the Lower Fox River system. The species that poses the most immediate risk? "The round goby," says De Stasio. A fish about six inches long, it feeds on the eggs of other species, including perch, bass, and potentially sturgeon. "It could have a large effect on the Lake Winnebago system," he says.
Because the spread of invasive species can't be stopped, only slowed down, De Stasio's goal is to educate students and the public to make them more aware of the potential consequences to the environment — a decrease in the populations of sport fish, degraded water quality on beaches, are just two examples. "These changes potentially affect all of us," he says.