Porites nubbin parts

"Po, po, po, Porites! Nubbin parts!"

- Cas, singing to the tune of the O'Reilly Auto Parts jingle

I told you Cas loves terrible puns. And I am not especially thrilled about this one getting stuck in my head. He sang it off-and-on for an hour the other day while I drilled, and Maikani picked up on the catchy jingle too. Ugh. 

A freshly-drilled nubbin hole

Well, we did get some spawning this month, but not nearly what we were hoping for in the end. It was enough to set up two small experiments but not nearly enough for our full experimental design. We can try again in May (that's actually supposed to be a bigger spawning event than April for our species), but in the meantime, we decided to deploy our back-up plan. 

Enter the nubbins. 

"Nubbin" is a term used by coral researchers to refer to miniature cores they collect from coral colonies. You take a circular drill bit, drill into the coral, and then break the core out with a chisel. Amazingly, the colonies live! I know plenty of researchers who have collected coral nubbins and used them for experiments. It's actually a super convenient technique.

So what did we do with the nubbins? Well, in this case, we're using them in a thermal stress experiment. We took two nubbins per colony and split them between a control and a thermal stress treatment. That way, we could get a direct comparison of how the same coral colony behaves in normal conditions versus thermal stress - one nubbin in each.

Nubbins in the heat stress
experiment

We set up tanks in the seawater lab at PICRC and added aquarium heaters to half of them. Over the next few weeks, we'll monitor the colonies for mortality and photosynthetic efficiency. If you're wondering about that last bit - photosynthetic efficiency - remember that corals have algal symbionts that use sunlight to fix carbon. When it gets too hot, the relationship between the coral and the zooxanthellae breaks down, and the corals bleach. Photosynthetic efficiency is a measure of how healthy those algae are, and how healthy the relationship is between the coral and their symbionts. 

Our thermal stress experiment should show some pretty cool patterns. We're using corals that belong to different genetic lineages with different baseline thermal tolerance levels, so we're expecting to see differences between them. The nubbins will reveal their secrets!