Planning and Prospects: Will We Find the Mysterious Clams?

A man looking for something on a rocky coast next to bright blue water

Searching for driftwood 

This is the seventh in a series of posts by Associate Curator of Invertebrate Zoology Janet R. Voight as she heads out on an expedition to Norway. There, she and colleagues will look for a wood-boring clam, Xylophaga dorsalis, to study its, well, poo. Read the first post and stay tuned for upcoming posts to find out what they discover.

We’re now in our third day here in Bergen, Norway, without having found any living wood-boring clams. The idea that we will spend the entire trip without a living wood-borer coming into our hands has been eating at me. It’s something that I suspected—I even said in the proposal, “the hardest thing about this project will be finding the animals.” In early summer, the people at the marine station here emailed me saying that they don’t see them very often. Ken Halanych, the co-principal investigator on the proposal, encountered the clams often during previous work a bit farther north, where the fjords have a different shape. He has a sense that they are also common here, but the people at the station don’t agree. Wood does, of course, wash from the land into the sea and in time sinks. The problem is finding the wood that has been on the bottom long enough for the larvae to have colonized it, settled and grown—but not so long that they have eaten ALL the wood. But, even at only 15 meters depth, how do you find it? As I have been thinking of these animals and their enigmatic borehole filling habit for a long time, wondering why they use the filler that they do, I fear disappointment ahead.

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A forested coastline
Searching for driftwood that may contain the wood-boring clams along the Norwegian coast

In our first morning, as we met the people at the station and found our way around, we met Professor Torleiv Brattegard. He has been a part of the station since beginning his master’s work a half-century ago. He has recorded the collections of new species in the area through the years on index cards and, more recently, computers. He records two Xylophaga dorsalis in the area. Bergen’s natural history museum has 40 lots of the species, but without online data, I don’t know where they came from. Their storage is off-site, meaning I can’t get to them for some time. When specimens are in off-site storage and a visitor makes a request to see something, a staff member has to go and get the material and bring it into the museum so it can be accessed. (I’m so glad we have our underground Collections Resource Center at The Field Museum to keep our specimens in the building, even if it is a bit of a hike and two elevator rides.)  

Will we find the live animals? I don’t know. In a week, we will have use of the larger boat, the RV (research vessel) Hans Brattström, which in the interim has been charted for other uses. As Henrik (who fed us the night we arrived) explained the issues that will complicate sampling, the knot in my stomach tightened. Because Bergen is Norway’s second largest city and is growing, more lobster traps and fiber optic cables are present at the depths where we want to work. Salmon farms line some of the fjords and have anchors that snag or rip nets. Of course, as good neighbors, those who work at the marine station don’t want to risk perturbing these and alienating their owners or losing their net.

The thing I rely on when my doubts grow is my experience working with remotely operated underwater vehicles (ROVs) in the deep sea. I once had a 14-day dive cruise in which the ROV did not work for 13 days. They fixed it, and on the final day, we collected the only known specimens of a new species of snail from hydrothermal vents that had hosted hundreds of dives. Sometimes you just have to be at the right place at the right time. 

Read on in Part 8: Tracking the Impact of Climate Change on Marine Animals

Funding for this project was provided by the Robert A. Pritzker Center for Meteoritics and Polar Studies established by a grant from the Tawani Foundation.