Dr. Walsh has studied the immune systems of marine vertebrate species, including the cartilaginous fishes (sharks, skates, and rays), marine mammals, and sea turtles, for more than 20 years. Current projects include research on cytotoxic factors produced by cultured shark immune cells, antimicrobial properties of epidermal mucus from stingrays, effects of harmful algal blooms on human health as well as on the health of wildlife species including the Florida manatee and sea turtles.