If the Coral Ain’t Broke…Well, Maybe We Should Try Breaking It?

Featured image: staghorn coral (Acropora cervicornis) in a Mote Marine Lab nursery. Photo by Conor Goulding/Mote Marine Laboratory

Reefs are in a spot, guys, a bad, bad, not good spot. If you aren’t aware of all the coral die-offs  and craziness like 30% of the Great Barrier Reef bleaching in just one year, well… you are now. It’s a gargantuan issue that I don’t want to get into here – you’re more than welcome to do your own research on that. Instead, I want to talk about research offering up some bright and shiny positivity! This piece is a follow up to one of the Rad As Hell articles I posted a few weeks ago about Dr. David Vaughan and the folks at Mote Marine Lab in Sarasota, Florida and their totally tubular technique for promoting coral growth.

You see, the majority of coral species grow quite slowly. We’re talking MAYBE 1 centimeter per year. Do you know what one centimeter looks like? That’s about the width of a pencil – #2 yellow Ticonderoga kind of pencil. That’s minuscule, hardly anything. The Great Barrier Reef is 2,300 kilometers, or 230,000,000 (230 million) centimeters. How long will it take for 69 million centimeters (30%) of that to grow back? A long-ass time is the technical answer. And that’s without considering things like how algae (or seaweed, if you prefer to use the lay terminology, and also be wrong) tends to move in where corals have died and prevent the corals from growing back. Not to mention further bleaching. Yikes.

So, Dr. Vaughan was understandably stoked when he observed rapid growth of the corals he was cultivating in his lab after he…er… dropped one and broke it. This observation spawned the experiment detailed in this paper concerning isogenic fusion. Holy science words Batoidman, let’s back it up. Corals, as most people think of them, are those colorful, alien, plant-looking things you see while snorkeling hungover on vacation because $5 mango daquiris are a bitch. In fact, each coral is a colony of hundreds or thousands (or even millions) of genetically identical little guys (re: clones) called coral polyps. And they’re not plants at all, they’re actually animals closely related to jellyfish and sea anemones. I know a lot of you probably knew that already, but I wanted to cover it just in case. So then isogenic fusion is when fragments from the same colony (isogenic means genetically identical) grow together and become one colony again (the fusion part). In nature this might happen when colonies are broken up by a storm or some other disturbance (like your foot, be careful!). At Mote Marine Lab, it happens when Dr. Vaughan drops them, thus, making a crucial scientific discovery.

Alright, let’s get back to this study now, shall we? So, when coral colonies are split into tiny pieces (~1 cm², think pencil eraser), they grow much quicker than normal. The question the authors set out to answer was: how much quicker? They primarily examined three species, Orbicella faveolata, Pseudodiploria clivosa, and Porites lobata – star coral, brain coral, and lobe coral. Chop ‘em up, glue ‘em to some tiles, then get out the measuring tapes (in actuality, the advanced photo analysis software). Four and a half months later, the results were staggering. Star coral had increased in area by 329% and brain coral by 154%. That’s a growth rate of 63.2 cm² per month and 47.5 cm² per month, respectively. Remember when I said coral in the wild grows about 1 cm a year? Yeah.

Now, it’s not so cut and dry to compare those numbers because measurements taken in the wild are typically how much taller or wider a colony grows, not how much it spreads out across a flat surface like in this experiment. But trust me (well, trust the study authors) when I tell you that these results are astounding. The lobe coral showed similarly rad rates of growth, but the experiment there was slightly different – comparing what happens when the fragments are grown in a brand new ‘clean’ tank all by themselves vs. an ‘established’ tank with other critters that more closely resembles a natural environment. Surprisingly, growth was better in the tank mimicking nature, a great find considering one use for the newly grown colonies is to transplant them into the wild for restoration of dying reefs.

Restoration is just one possible application of rapidly-grown corals, they can also fuel further research by providing easy access to plenty of experimental subjects – without the need for wild harvest. Speaking of, the sustainable harvest of coral resources, an important source of pharmaceutical compounds and breakthroughs, could have wide-ranging impacts on global health and well-being.

The application of this fragment-fusion method succeeds in covering a large area quickly, though thinly – which as I mentioned is not quite the same as natural colony growth in the wild. But there are benefits to rapid growth of this kind, namely increased survivability, reproductive output, resource sharing, and competitive advantage. Basically, the larger a coral colony is, the easier time it has getting food and staying alive, so instead of worrying about those things it puts energy into churning out coral babies. And that’s how restoration of places like the Great Barrier Reef will really succeed, not by replacing all the lost corals with ones grown in the lab, but by using them to jump start the natural replenishment of the ecosystem.

A good deal of work needs to be done before that dream is possible – who knows, maybe this method of growth has some unknown effect on coral that can’t be seen in just a few months of study? Still, it’s a damn good start for a happy accident.

Johnny Venger grew 0 cm in 2018, probably because he refused to break off any limbs.

References:

Forsman et al. (2015), Growing coral larger and faster: micro-colony-fusion as a strategy for accelerating coral cover. PeerJ 3:e1313; DOI 10.7717/peerj.1313