Berta.

Her name is Berta. 

She spends most days lying on Polarstern's stern. Sometimes, she goes for a long, deep swim. She is made of metal and mesh. Her insides hold untold mysteries of the Arctic deep sea. 

I was pretty pleased with my completed net.

That's right, Berta is a piece of sampling gear - an epibenthic sledge, to be exact. There's a team on board Polarstern right now that uses their affectionately-named sledge to collect samples from right above the seafloor. The more I talked to the team leader, Saskia, the more we realized that Berta could be a valuable tool for collecting larvae, too. 

In my seemingly endless search for Arctic deep-sea larvae, the hardest habitat to reach is the water right above the seafloor. Yet, that's where I suspect many of the larvae might be. I've tried all sorts of different ways to collect and filter water from the very bottom of the ocean - I have deployed a high-volume plankton pump on a lander and even left long-term larval traps on the seafloor. Why not try an epibenthic sledge? 

Berta's mesh is 300 μm, which might sound small to you but is actually quite large for larvae. They would pass right through. Thankfully, I had brought spare 63 μm mesh on board Polarstern. Saskia and I struck a deal. If I could make a net that fit inside Berta, Saskia's team would figure out a way to attach it. After each deployment, we would sieve the contents of my net at 300 μm. Saskia's crew would take anything that was retained on the sieve, and I would get anything that flowed through. They get larger animals; we get larvae. 

One of the polychaetes we caught, magnified 50x.

This isn't the first time I've spontaneously fabricated new sampling gear from the scraps I have with me at sea. These days, I travel with plenty of spares, just in case an opportunity crops up. I gathered the materials I would need: my spare mesh, a ratchet strap to reinforce the seams, an embroidery needle (also used to manipulate larvae under the microscope), and dental floss (it's stronger than thread and actually preferable for plankton nets). Rummaging through my spares, I found my nail polish, which can help seal and reinforce Frankenstein-style repairs to ripped nets, but I wouldn't need it for this job. It was actually pretty satisfying to find everything I needed right away. Ain't my first rodeo. 

My net was bolted into Berta's frame and baptized at 2500 m depth. The coolest part is that we actually caught something - two segmented worms (polychaetes) from the water right above the seafloor. We have no idea what species the worms are, but that will be a problem for DNA analysis back home. I'm grateful to Saskia for allowing me to try something new and look forward to slowly building our dataset of Arctic deep-sea larvae!