Infectious disease in marine life linked to decades of ocean warming

The paper, "Increases and decreases in marine disease reports in an era of global change," was published Oct. 9 in Proceedings of the Royal Society B.

Understanding oceanic trends is important for evaluating today's threats to marine systems, and disease is an important sentinel of change, according to senior author Drew Harvell, professor of marine biology at Cornell University.

"Disease increases and decreases can both be bad news," said lead author Allison Tracy, who studied with Harvell. "The long-term changes in disease that we see here may result from anthropogenic pressure on plants and animals in the ocean."

The researchers examined marine infectious disease reports from 1970 to 2013, which transcend short-term fluctuations and regional variation. They examined records of corals, urchins, mammals, decapods, fish, mollusks, sharks, rays, seagrass and turtles.

For corals and urchins, reports of infectious disease increased over the 44-year period. In the Caribbean, increasing coral disease reports correlated with warming events. It is widely known that coral bleaching increases with warming, but Harvell said they have established a long-term connection between warming and coral disease.

"We've finally linked a coral killer like infectious disease to repeated warming bouts over four decades of change," she said. "Our study shows that infectious disease reports are associated with warm temperature anomalies in corals on a multi-decadal scale."

These results improve understanding of how changing environments alter species interactions, and they provide a solid baseline for health of marine life in the period studied.

The research was funded by a National Science Foundation Ecology and Evolution of Marine Infectious Diseases grant.