Scientific research, especially with live animals, is inherently high-risk. It turns out it’s really hard to care for a species you know almost nothing about, let alone get them healthy and happy enough to spawn. Very little is published on the Purple-hinged rock scallop, Crassadoma gigantea, and folks are just now developing methods for commercial production. Although my research team had good reasons to believe we would be able to spawn our animals for a larval common garden experiment with a low pH treatment, it never really happened. Sometimes one population would spawn, but others wouldn’t. Sometimes a few would spawn on a Friday afternoon when everyone had left the hatchery. But alas, they never spawned the way we needed them to and we finally cut our losses this summer. A year of of my PhD preparing for an experiment ended without any data. But out of the flames came a tiny, beautiful phoenix…
We decided to use the adult scallops we’ve kept alive to do a similar experiment. I have four populations of scallops, one from Alaska, one from California, and two from Washington, and I split them between ambient pH and low pH treatments, with four replicate tubs each.
This week, we dissected some at Time Zero, before the low pH treatment was turned on, and then at Time One, after half of the animals were exposed to low pH for 48 hours to look at the physiological response to short-term exposure to low pH. In about 6 weeks, we’ll sample them one last time at Time Two, for long-term exposure. Hopefully we’ll be able to make population comparisons. But at the very least, we’ll get some insight into the species’ physiology and what might be coming with ocean acidification.
We collected samples for SO many things. First, we sampled five tissue types for RNA and two for proteins to look at RNA and protein expression. Those are the most time-sensitive and needed to be quickly immersed in RNALater or flash-frozen in the first couple of minutes. Then, we sampled other tissue types for lipid analysis, and others for microbial community. We weighed the scallop, took slivers of the gonad for histology, and classified the color of the mantle.
And getting inside these animals is not easy. Fortunately, we had a room full of experienced shellfish shuckers. And a LOT of shucking knives.
Alongside the biological sampling we are sampling seawater chemistry. Our water treatment system that makes low-pH seawater has Durafet pH sensors to manage the pH of the water by adding CO2 to drop the pH to a target. One of the four replicate tubs per treatment also has a Durafet, so that we can ballpark what pH our treatments are at. Then, on a daily basis, we collect discrete seawater samples from all the tubs in each treatment and the water header tanks to measure pH, salinity, and temperature. At the same time, we collect a water sample to measure total alkalinity later in the lab. Altogether, this gives us a clear picture of the carbonate chemistry experienced by the scallops.
Sampling days for most projects are often chaotic and strenuous. Everyone’s frantic and tired, and you have to provide cupcakes and donut holes to keep the calm. Somehow, these sampling days went off without a hitch. I should have known, since I have an amazing team of collaborators and many experienced shellfishy peers that are always ready to volunteer their skills.
And moreover, I had legit good omens from the universe. On our way out to sample at Time Zero, we saw the whole J Pod of resident killer whales right off the beach at the Fauntleroy ferry terminal.
And right after finishing the sampling at Time One, we had 45 minutes to kill at the ferry with Buster the 12-week-old border terrier.
What a rush to finally have samples in the freezer. Now, I just need to monitor the seawater chemistry and make sure the system stays stable until our last sampling day sometime in November. Fingers crossed nothing explodes!