Spawn watch 2022: part 2

Eggs being released from Porites lobata. 
Photo by Maikani Andres.

I had just gotten into the water when I heard Maikani's faint voice. She was exclaiming about something. Matt heard her better than I did. "They're spawning?" he shouted back to confirm. 

I didn't really hear the answer, but the fact that Matt took off running was a good sign. I climbed out of the water, doing my best not to scrape my legs on the sharp oyster shells, and followed them both over to the tank room. 

Yep, we got spawning! Two individuals gave us their gametes - one male, one female. From the lineage we needed the most, from the site we needed the most. It was what we had been waiting and wishing for. Cas said we manifested the spawning by putting our desires out into the universe. Maikani insisted the corals spawned because she had played them a Marvin Gaye song earlier in the night. Matt wanted to know which song it was, because apparently a species he's worked on in the Caribbean prefers Ed Sheeran. 

Whether it was the mood, manifestation, or a matter of patience, we got the spawning we wanted. I was overjoyed. 

Unfortunately, only a small proportion of the larvae made it through the night, but we will take every individual we can get. A small experiment could still show important trends. 

A Pest Plug (can we trademark that?). Water 
flows in over the coral nubbins at the top, and
we deploy the nudibranch in the clear chamber
at the bottom. When it chooses a coral, we 
see it emerge in the clear chambers at the top.

Now, let's back up and talk about why I was climbing into the ocean at 9 pm in the first place. We had been watching our colonies for several days and not seen any hint of reproduction. We were beginning to think about interesting experiments we could do with the organisms we had, and so I went hunting for nudibranchs. You'll remember that we found several Phestilla lugubris (aka Pesty Goobers) munching away on our corals. The vast majority of them were found on colonies from a distinct genetic group (we call it "Lineage 1"), which was honestly a bit weird. Cas has this theory that predators can identify cryptic species using cues that humans don't normally perceive. For example, maybe a fish is swimming along, and a coral smells really good, so it takes a bite. Then it keeps eating corals that smell similar, and as it turns out, those tasty-smelling corals emit whatever molecule the fish likes because they have distinct DNA that codes for it. It's a theory. 

We were planning to test Cas' theory by putting the nudibranchs into Y-shaped chambers with water flowing over two nubbins from two different coral lineages, then watch which one the nudibranchs crawled towards. Matt designed the chambers - he called them Pest Plugs ("Plug" being short for P. lugubris). The design worked super well. We did a few preliminary trials with a coral nubbin on only one side, and the nudibranchs went to the nubbin every time. They could smell their food and crawl towards it. 

We never got the chance to do many trials with the lineages (a choice between two nubbins) because spawning started, but I still think the idea is super intriguing. The team had a very fun time imagining future scenarios in which we deploy trained nudibranchs in a field of corals and watch which way they crawl to find individuals from the genetic lineage we want. It would be entertaining and save a lot of lab work!

It was a great night, and I'm so glad we got spawning!