VibrioBOD

A few months ago, I was chatting with a WHOI postdoc, Carolin. She casually mentioned that she had an idea for an experiment using coral larvae, but because no reef-building corals live in Massachusetts, she was going to do the experiment with oysters instead. Oysters are a poor analogue for corals - in fact, they're hardly comparable at all - but she felt it was her only option. 

"What about anemone larvae?" I asked. Anemones should be very comparable to corals - both are cnidarians, so they have the same larval form, a planula. 

VibrioBOD set up in a lab at WHOI

"Well, that would be great," Carolin responded, "but where could I get anemone larvae?" 

"From me," I answered. Her face lit up, and a collaboration was born. 

The driving question for Carolin's experiment is "How do marine larvae react to sound?" A lot of experiments have addressed how adult animals react to sound - and in most cases the reaction is negative. Scallops close their shells, corals draw their tentacles in, and whales avoid the noisy area. The net result is less feeding, less respiration, and more stress for marine animals. 

But what about when they're young? Are marine larvae stressed by sound the same way they are as adults? 

To find out, Carolin plans to use a newly-invented machine called VibrioBOD. There's only one of them in the world, and in fact, it was built specifically for Carolin's experiment. You see, another postdoc, Clarissa, had conducted research on marine snow using a special instrument that she invented called the RotoBOD. The machine rotates constantly to keep particles in suspension and can measure extremely small changes in oxygen to show how much microbes are respiring. Carolin and Clarissa together realized that if RotoBOD were vibrating instead of rotating, it would simulate the transmission of sound in the ocean - and we could use respiration rate as a proxy for organismal stress. 

All I had to do was provide the two bright, motivated postdocs with some anemone larvae. Unfortunately, the anemones had other plans and failed to spawn this year. But we were undeterred. If the anemones didn't want to cooperate, we would find other larvae! Last week, that is what we did. 

Carolin, Clarissa, and I on the dock with some bryozoans
and ascidians that we tried to spawn

Clarissa, Carolin, and I met on the dock right outside my office at 8 am. We dragged a plankton net through the water, emptied its contents into a jar, and examined our catch under the microscope. There were plenty of larvae to go around! Sharp, pointy zoea and round, smooth trochopores. Swimming nectochaetes and speedy nemerteans. I grabbed several individuals and set them aside in dishes. 

Our first run of the VibrioBOD experiment was instructive, to be sure. The instrument needs some fine-tuning, so it's actually good for us to get a slow start. We were able to measure oxygen use, but Clarissa said the curves looked more like microbial respiration than larval respiration. Next time, we need to use a finer water filter to make sure we remove all the microbes! With some tweaks and another try, we should be able to hone our approach to the experiment. I am looking forward to exciting data!