Tape it 'til you make it

For a while now, I have mentored an intern named Hollis. He was matched with me through a mentorship program at his school and stayed on as a volunteer over the summer. We're now in the second year of mentorship, and Hollis and I are already scheming about ways to keep working together long-term. He's still in high school, but he's already becoming a full-fledged member of the team. 

Hollis spent most of last year helping to sort larvae from the high Arctic, but this year, I wanted to introduce him to new techniques. We're working together on an analysis of scallop larvae from Georges Bank. The task sounds simple: count how many scallop larvae are in my samples from each station. But that is easier said than done. 

The samples are thick. Scallop larvae are tiny, so I had to use a super fine mesh net to collect them. So fine, in fact, that the net didn't just catch the larvae - it caught all the diatoms that were in the water, too. We're basically hunting for tiny scallops in an algae soup. It took Hollis and me 2 hours to get through the first sample. There are 45 samples total. I did some quick math in my head. Yep, at that rate, it was going to take the entire school year to get through the samples. We needed a faster method. 

Our tape-laden funnel set-up

Thankfully, I found a paper from the late 1980s with a suggested technique for separating baby scallops from the rest of a plankton sample. The technique takes advantage of the fact that baby scallops (well, all bivalve larvae) have heavy shells. You pour a small amount of colloidal silica, which is denser than water, into a narrow funnel. Then you add your sample (in water!) on top. The bivalve larvae sink, and everything else floats. Siphon off the heavy fraction from the bottom of the funnel, rinse off the silica, and voila! You have separated the bivalves from the rest. 

I bought the necessary supplies - colloidal silica and a funnel. When Hollis came to the lab for his next  session, I knew we would have some fun setting everything up together. I showed him the supplies. I asked his opinion about how we should set everything up. He shrugged.

"Tape it 'til you make it," he said. 

Our final set-up includes a large PVC pole, the ring from a Ball glass jar lid, and copious amounts of duct tape. It is truly a mind meld of Hollis and me. I fashioned a sieve out of spare mesh and a needlepoint hoop. We donned nitrile gloves, measured our first aliquot of silica, and set to work. 

It worked. Not only that, but the results look amazing. Three out of my 10 stations very clearly have more bivalve larvae than the rest. We still have to verify that the bivalves are scallops using DNA, but that's a separate story. I am so proud of the ways Hollis has grown and become a contributing member of the lab. I'm glad that I get to work with him for another school year and look forward to what we will find together!