The researchers quantified parasites and free-living organisms in the Carpinteria Salt Marsh in California, and in the Bahia San Quintn and Estero de Punta Banda estuaries in Baja California. Their study included 199 species of free-living animals, 15 species of free-living vascular plants, and 138 species of parasites.
"A lot of work we've done has suggested that parasites are important in ecosystems," said Lafferty. "But no one's actually looked at them as a group throughout an ecosystem."
"Also, no one's considered parasites from the perspective of how much they weigh, because it's always been assumed they weigh almost nothing," he said. "Now we know that's not true."
For example, in an estuary there are more kilograms of trematode worms--parasites--than kilograms of birds, the scientists found.
The study's results have a potential impact on the perceived role of parasites in the ecosystem. From an ecological perspective, parasites serve both as regulators to prevent species from becoming numerically dominant, and as indicators of the health of a particular ecosystem.
"No one debates whether it's important for ensuring human welfare to understand how ecosystems work," said Hechinger. "How can we understand something without accounting for its major parts?"
According to Kuris, understanding the enormity of parasite biomass and the burden it places on available hosts could lead to new strategies in the management of infectious diseases.
Treatment protocols might put greater emphasis on enhancing the host's ability to defend itself against parasitic disease and slow the rate of energy uptake by the parasites and pathogens.
"The total amount of energy f
|Contact: Cheryl Dybas|
National Science Foundation