Ødegård set off aboard the Arctic University of Norway’s research vessel Helmer Hanssen last summer, with the aim of finding Dutch ships sunk by the French in the 17th century. Using historical reports made to France’s King Louis XIV, Ødegård and his team pinpointed promising spots. But when they deployed underwater drones for a closer look, they not only failed to find Franklin-esque wrecks—they found nothing at all.
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The absence suggested an awful possibility: The wrecks—which no one had attempted to find in the past—had once been there, but had vanished. The suspected culprit? Shipworms, one of the world’s most voracious destroyers of underwater heritage.
Not worms at all, shipworms are tunneling, tube-shaped mollusks that thrive on cellulose. A sizable infestation can destroy a sunken ship in just a few years, exposing to the elements the trove of historical treasures contained inside, from human remains to archaeological artifacts.
Shipworms have long been a recognized threat, but before 2016 no one had realized they could endanger the abundant but unexplored wreckage sprawled across the Arctic seafloor—where it was assumed to be far too cold for them to thrive. That year, however, Arctic University of Norway marine biologist Jørgen Berge led an expedition (which also included Ødegård) to the water off Svalbard to investigate a Norwegian whaler called the Figaro, the world’s northernmost-known wreck. The Figaro appeared in good shape. But during the expedition, the team also hauled up a seven-meter tree trunk riddled with live shipworms.
The idea that shipworms may be threatening Arctic wrecks was reinforced in 2019 when Ødegård’s team found boreholes in wood collected from Svalbard beaches. A closer inspection of the Figaro also turned up previously missed evidence of shipworm infestation.
Taken together, the findings suggest that underwater heritage in Svalbard—and perhaps across the world’s northern oceans—may not simply be lying in situ, cleanly preserved and waiting to be discovered. They also raise new questions about the role that ocean currents and climate change may be playing in bringing masses of warm water into the Arctic and subarctic. Researchers aren’t sure whether the shipworms found in 2016 were a southern species that’s moved north or a newly discovered species that thrives in colder waters; genetic sequencing is underway.
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“There’s an imminent need to explore more widely,” says Berge. “If [wrecks] are already in the process of being eaten up, we may already have lost our chance to learn from them.”
Ødegård is now planning to collaborate with other researchers to get a better handle on the shipworm situation in the western Arctic. Once the COVID-19 pandemic permits, climate historian Matthew Ayre of the University of Calgary in Alberta hopes to work with Ødegård to locate wrecks near Greenland and assess the shipworm threat there.