Parasites have long been cast aside as microscopic pests, but a recent study from UCSB is calling for a reexamination of the role these organisms play in ecosystems.

The study, carried out at three estuaries in California and Mexico by 18 researchers from UCSB, the United States Geological Survey and Princeton University, revealed that parasites greatly outnumber predators not just in numbers, but also in weight.

This revelation — that the biomass of free-living and parasitic species surpassed that of the ecosystem’s prevailing predators — flies in the face of conventional wisdom and could have considerable impact on future biomedical and ecological studies, researchers said. Ryan Hechinger, a researcher at the UCSB Marine Science Institute and co-author of the paper, said the findings represent an opportunity for the scientific community to rethink parasites.

“In this light, I think of our findings mostly as opening the door for creative thinking,” Hechinger said.

For example, Hechinger said, the research may arm scientists with new approaches in fighting disease.

“An appreciation of where most of the biomass lies for an infectious disease might help direct where you focus your efforts in controlling the disease,” Hechinger said. “Therefore, [understanding] that there is a large biomass of infectious agent inside hosts might open the door to new ideas on how to treat the disease.”

Hechinger said a proper understanding of the breakdown of biomass may also aid efforts to combat infectious diseases that have already been contracted by individuals.

“There might be creative ways to deal with being sick that also pay attention to the large biomass and energetics of infectious agents within individual hosts,” Hechinger said. “It might really help us figure out what’s really causing the sickness, or where it would be best to limit or break the success of the infection, or where it would be best to help the host fight the infection.”

According to Hechinger, although parasites are typically ignored because of their microscopic size, they are of great importance to the balance of ecosystems.

“Parasites are generally out of sight and have frequently been out of mind in the planning and implementation of ecological studies,” Hechinger said. “What we’ve found is that they really shouldn’t be out of mind. This is because they are there, and in large amounts.”

The research, published in a July issue of the science journal Nature, was funded by a $2.2 million grant from the Ecology of Infectious Diseases Program and was carried out in the Carpinteria Salt Marsh in California and the Bahia San Quintin and Estero de Punta Banda estuaries in Mexico.