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By Cara Byington
It was the kind of surreal conversation that could probably only happen in a place like Key West. (Or maybe things like this only happen to me).
It started when a young couple sat down next to me in Mallory Square and noticed my somewhat ragged field guide to coral reefs. They were visiting from Michigan, they said, and going snorkeling on the reef the next day.
Happy to talk about how much I love the reef and how threatened it is, I opened my book to the color pictures in the middle and pointed out the corals that they might see on their trip and that are easy to identify – fire, staghorn, brain, the coral that looks like cheerios – and some of the more iconic fish.
“Maybe you’ll see a parrotfish.” I turn to a green and orange fish that looks like it might be smiling. “They kind of graze on the algae on the reef and take an occasional bite of coral and if it’s quiet enough and you’re close enough, you can sometimes hear the crunching sound. Like sitting too close to someone eating chips.”
“They eat the coral? I thought coral was rock. Like thousands of year old rock.”
“Well, it is, but the first few millimeters of the reef are alive.” And covered with a kind of mucus, but I don’t say that. Instead, I give them a short and simplified version of coral reef 101.
It goes something like this: Coral reefs are essentially built by very, very small animals called polyps. They secrete calcium carbonate –limestone – that forms the foundation of the reef and, as long as the polyps are living, the reef will gradually grow outwards and upwards, with the polyps always on the surface.
The polyps live by capturing zooplankton and phytoplankton out of the water and by photosynthesis, aided by algae called “zooxanthellae.” Because corals need a precise combination of water clarity, temperature and depth, they only live in a few specialized places in the world’s tropics.
Most corals grow very slowly and any alterations to their environment – such as those caused by climate change – can have fatal consequences. The heat from rising water temperatures, for instance, causes corals to bleach. And as the waters are warming, they are also sucking up more CO2 and becoming more acidic over time. If acid levels are too high for too long, the corals can’t produce new skeletons (the calcium carbonate) and may die.
But, even given all of that, there is hope for coral reefs and the Conservancy and its partners work hard all over the world to ensure that ours is not the last generation to see living coral in the wild.
I’m congratulating myself on my two-minute explanation of coral reef ecology, the challenge of climate change, the Conservancy’s work, and (thanks to Meaghan Johnson) my ability to accurately pronounce “zooxanthellae,” when I realize the quality of the silence has changed.
Eyes wide, the woman asks, “You’re saying coral reefs eat? Like, eat eat? Meat?”
Well, it’s more like they digest. And though I wouldn’t exactly call zooplankton “meat,” they are animals; microscopic animals, but still animals. The corals capture zooplantkon as well as phytoplankton (tiny plants) as plankton rich water moves over the reef. Technically, corals are omnivorous and so yes, they do, like, eat eat other animals. But only really, really small ones.
Searching for a way to clarify, I – mistakenly as it turns out – go with the coral-is-living-rock metaphor. It’s not exactly scientific, but for general purposes, you can think of one part of the reef as living and one part (the calcium carbonate) as dead.
They look thoughtful about that and then the man, instead of saying something I expect like, “wow, I never knew reefs were so special,” he says (and I quote), “That’s so cool. Coral reefs are like zombies! Alive and dead, living on flesh.”
Wait. What?
Even in my admittedly vast history of odd conversations, I have never gone from zero to zombie quite so fast. And all I can think is that tomorrow, on some dive boat somewhere, these people are going to tell the dive master (and all the other snorkelers) that this writer from The Nature Conservancy told them that coral reefs are like zombies.
And since I am, at the moment, the only Conservancy writer working in the Keys (which means I am highly identifiable) and have a broken leg (which means I am unable to flee the conversation), I scramble to salvage what I can.
Calling on the limited knowledge of zombie lore I gleaned from the movie “Shaun of the Dead” and, with great caution and a silent apology to all the marine scientists I work with, I clear my throat and venture back into the fray with, “Well, not exactly. For one thing, calling zooplankton ‘flesh’ is a stretch. And also” – I cannot even believe I’m saying this – “zombies are very tough and hard to destroy. Corals, on the other hand, are amazingly fragile. The careless brush of a scuba fin or a hand can kill them and, unlike zombies, they tend to die slowly, silently and without drama.”
Or gore, which my tourists point out, may be unfortunate.
“That’s too bad,” the woman says. “Because that bleaching sounds really scary. If corals bled and made noise, and, you know, were above water -- maybe more people would know about the scary things that are happening to them.”
Which is, you know, true. And as we all turn to watch the famous Mallory Square sunset, it occurs to me that my Michigan tourists are right about something else as well. What’s happening to coral reefs all over the world is more frightening and, unfortunately, more real than any zombie movie ever made.
Cara Byington is a senior writer for The Nature Conservancy. She lives in Florida and writes on global conservation issues, including marine conservation in the Florida Keys and the Caribbean. You can email her with questions and/or zombie movie suggestions at cbyington@tnc.org.
Nature picture credits (top to bottom, left to right): Photo © HalBrindley.com (coral reefs); Photo © Craig Quirolo, Reef Relief/Marine Photobank (bleached coral).
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