Snotty biofilm feeds millions

More than a million Western Sandpipers stop to feed on the Roberts Bank mudflats of the Fraser River estuary during their spring migration.

Dr. Bob Elner, Environment and Climate Change Canada Scientist Emeritus, walked out onto the mudflats one spring and wondered why these shorebirds, which normally eat invertebrates, were feeding on the apparently barren mudflats.

His scientific curiosity spurred novel research on the role of biofilm, a thin gelatinous layer secreted by microorganisms, covering the mudflats, in the diet of migrating shorebirds.

The phenomenon of biofilm feeding was first recorded by Dr. Tomohiro Kuwae, a visiting postdoc from Japan, by taking high-speed video footage of the Western Sandpipers feeding on the mudflats. The findings were first published in the journal Ecology in 2008.

Western Sandpipers have hairy tongues covered in mucous, with large batteries of taste buds.

“Their snotty tongues are adapted to slurp up snotty biofilm,” said Dr. Elner. “They love the taste of these rich microbes and polysaccharides.”

Western Sandpipers need the Omega-3 fatty acids produced by diatoms in the biofilm to fuel their long-distance migratory flight to the Arctic to breed. Diatoms form the base of the food chain, and the nutrients they produce help to fatten up many species including polar bears, salmon and Western Sandpipers.

“When these small critters bloom, they produce essential Omega-3 fatty acids, and they are the primary source on earth for them,” said Dr. Elner. “When you’re watching 50,000 shorebirds feeding on biofilm with such intense concentration that you can walk right up to them, you realize the ecological importance of the situation and the need for greater scientific understanding in order to conserve these systems.”

Dr. Elner and his colleagues’ findings are already being used in helping balance coastal development and conservation issues in British Columbia.