A leader of amphibian ecology and wetland conservation, Semlitsch is well-known for his research on the mechanisms of persistence of amphibian populations in altered habitats. His studies on the chemical contamination of farmlands have documented that tolerance to direct contaminants, such as insecticides, varies among species of amphibians, and that sub-lethal concentrations for amphibians have an indirect effect on food resources that cause mortality. He also established the ecological connection between aquatic and terrestrial environments for semi-aquatic amphibian species and defined the land around wetlands as an essential part of a species' "core habitat" and critical for management and protection.

"Dr. Semlitsch's research has spanned from basic ecology and life history evolution of amphibians to applied work on conservation of amphibians — work that will have a lasting impact on the way we will conduct science for years to come," said Michelle D. Boone, associate professor of zoology at Miami University, who nominated Semlitsch for the award.
Recently, he drew popular attention with research that showed that amphibian populations could thrive in properly buffered golf course ponds as well as in sustainably timbered forests.