Dr. Joel Hoffman's research on fish habitat is broadly concerned with the effects of non-point pollution on fish ecology and habitat in the Great Lakes. He is interested in how non-point source pollution – particularly nutrients and sediment – affect coastal water bodies. He is looking at coastal eutrophication and how local fish species react at the species level.

"Now we can say we’ve actually altered the very nature of the carbon and nitrogen nutrients in the carbon cycle."

One of the tools Joel uses is mathematical modeling, looking at the statistical probability that a certain species will be in a certain place relative to degradation of the ecosystem. He is also looking at how their geographic range may be altered as a reaction to ecosystem degradation, using chemical markers in tissues to make these assessments. These markers are stable isotopes – carbon and nitrogen – and stable isotope signatures are unique. "Because of the differing quantities of cycling carbon and nitrogen, as these signatures travel up the food web we can tell where the fish is spending its time," says Joel. "So as a wetland degrades we can ask: 'Is the fish spending less time there?'" These signatures are sensitive indicators for changes to the ecosystems and can reflect how a loss of value can occur.