Australasian Science: Australia's authority on science since 1938

Barnacles Trace Turtle Migration

The shell chemistry of barnacles may enable scientists to determine the migratory origin of endangered loggerhead turtles.

“To conserve loggerhead turtles, we need to know which parts of the ocean they use and when they use them,” says PhD student Ryan Pearson of Griffith University. “Scientists have tried to do this by measuring the chemical composition of the turtles, but this doesn’t always work. Not all turtles within a group eat the same things in the same places, so sampling skin tissues from a few doesn’t always tell us the big picture.”

Enter barnacles. “Because barnacles are filter feeders, they all eat the same things in the same places, so their chemical composition will more accurately reflect where they’ve been in the ocean compared with the turtles.”

Pearson is attempting to circumvent the concerns of using turtle tissues by analysing the stable isotope signals within shell layers of barnacles that go along for the ride on migrating south Pacific loggerhead turtles. “These shell layers offer chemical information about the area of the ocean in which the turtle has been swimming and, therefore, could allow us to identify the migratory origin of nesting turtles,” he said.

“If successful, this method has the exciting potential to be applied not just to loggerheads but to any other migrating marine species that has commensal barnacles,” said Prof Angela Moles, Vice President of the Ecological Society of Australia, which has awarded Pearson its 2015 Jill Landsberg Applied Conservation Scholarship.

“Ultimately there is also the potential to track the source of other objects that wash up on our shores, perhaps even components of missing aircraft or ships,” Moles said, referring to the recent discovery of barnacle-encrusted debris from missing Malaysian Airlines flight MH370.