I grow tomatoes, which means I spend an unreasonable amount of time trying to interpret things that can't explain themselves to me. A leaf droops, growth slows down, something looks slightly wrong, and suddenly I'm standing there conducting an interview with a plant. It has never answered, but that hasn't stopped me yet.
Gardening makes you notice that the past doesn't disappear when the weather improves. A damaged stem can remain damaged after a beautiful week, and a plant's current appearance doesn't tell you everything it has already been through. That was what caught my attention about coral reefs and the idea that they can remember storms.
The word remember is doing some work here. Corals aren't replaying a hurricane in their minds, and a reef isn't keeping a diary with increasingly irritated entries about the weather. But storms can leave evidence in skeletons, broken reef structures and the community that survives afterward. Some of that evidence lasts long enough for scientists to investigate years or centuries later.
I like that version of the story better than the mystical one. We don't have to give a coral colony our thoughts for its history to matter. We just have to learn what we're actually looking at, which turns out to be considerably more interesting than a reef having a grudge against September.
First, the Reef Is Alive
A coral reef can look like an elaborate arrangement of rocks, particularly in a photograph taken from far enough away. The reef-building corals we're talking about are animals. Their colonies consist of small polyps, and the hard framework beneath their living tissue is a skeleton they build from calcium carbonate.
That distinction matters to me because it changes how I imagine damage. A snapped coral branch isn't simply an attractive underwater decoration breaking. Living tissue may be injured or lost along with part of the structure, and other organisms depend on that structure for space and shelter.
There is also a difference between an individual coral colony and the reef around it. The colony is one contributor to a much larger physical and ecological system. Saying a reef recovered might mean coral cover increased, the community changed, or the framework became more stable, depending on what someone measured. Those aren't automatically the same outcome.
My genetics background makes me a little stubborn about this kind of distinction. I want to know what a study actually observed before I decide what its conclusion means. Otherwise we can take a perfectly good result, attach a much bigger explanation to it, and end up repeating something the researchers never claimed.
A Storm Does Several Things at Once
The obvious damage comes from powerful waves and moving water. Branching colonies can snap, colonies can be displaced, and loose material can strike or scrape other parts of the reef. A shape that provides wonderful branching habitat can also present a lot of surface for water to push against.
NOAA's account of hurricane effects on sea life also describes changes in salinity, water mixing and suspended sediment. Heavy rain and runoff can freshen coastal water, while stirred-up sediment can reduce the light reaching corals. The disturbance isn't limited to the moment a wave breaks a branch, and different places experience different combinations of stress.
I find that useful to remember when looking at an after-storm photograph. Clear water in the picture doesn't tell us how much sediment was suspended earlier. An upright colony doesn't tell us that every part of its environment stayed within comfortable limits. The damage we can see is only part of the investigation.
It also explains why I wouldn't expect two reefs to respond identically to the same named hurricane. Their depth, exposure, shapes and surrounding coastline differ. In a USGS-published study of hurricane resistance, the configuration of the reef and its exposure helped explain differences in damage. A storm name is a starting point for the story, not a complete description of what happened at every colony.
The Skeleton Has a Timeline
Some massive corals build skeletons with annual density bands. Researchers can see those bands in X-rayed slices and use them to examine growth through time. The comparison with tree rings is helpful, provided we don't assume every coral grows an equally tidy set of rings or every band announces a particular storm.
NOAA's Flower Garden Banks explanation describes how scientists take cores from large colonies to examine the record inside. This is skilled research involving specialized equipment and care for the colony afterward. In the method NOAA describes, the opening is patched so living tissue can grow across it. Taking a core creates an injury; it isn't a harmless souvenir collection technique.
What interests me is the change in scale. From above, you might see a large rounded colony sitting on the seafloor. In a prepared slice, that same skeleton becomes a sequence of growth that can be dated and compared with other evidence. A familiar-looking lump of reef can contain a record longer than the local weather station's.
That doesn't make reading it effortless. Researchers need a reliable chronology and a reason to connect a particular change with a particular environmental condition. A narrow band could invite a question about stress, but it doesn't arrive with a tiny printed label saying hurricane, Tuesday afternoon, very unpleasant.
Chemistry Adds Another Part of the Record
Growth bands help establish time, while the skeleton's chemistry can provide clues about the conditions in which it formed. NOAA's National Centers for Environmental Information describes the use of coral records to investigate past water temperatures and rainfall-related changes. These are proxy records: measurements that help us estimate environmental conditions rather than a thermometer that somebody left running inside the coral.
A proxy needs interpretation. Temperature, water composition and the particular measurement being used all matter, so scientists compare records with observations and other evidence. I don't hear the word proxy as a reason to dismiss the research. I hear it as a reminder to ask how the measurement was calibrated and what its uncertainties are.
That is probably the genetics student in me showing up again. The exciting part of a result isn't improved by pretending the method has no limitations. If anything, understanding what the method can and can't tell us makes the result more useful, because we know which questions it can reasonably answer.
It's also why a coral core can't automatically provide a complete list of every storm that crossed a region. Different disturbances can affect growth or chemistry, and some events leave little recognizable signal in the sample being studied. A natural archive is valuable without being a perfect recording of everything that happened nearby.
Floodwater Can Leave a Different Kind of Clue
The Australian Institute of Marine Science describes bright luminescent lines visible under ultraviolet light in slices from nearshore Great Barrier Reef corals. In that setting, the lines are related to freshwater flooding and rainfall. Researchers have used those records to reconstruct past rainfall and freshwater flow into the reef over periods extending well beyond the instrumental record.
This is one of my favorite details because the connection reaches inland. Rain falls over a catchment, rivers carry water toward the coast, and a coral skeleton can preserve evidence related to that freshwater influence. The history of a reef doesn't begin and end at the edge of a pretty blue photograph.
But a flood signal and a hurricane signal aren't interchangeable. A flood can occur without a tropical cyclone, and a cyclone's effects vary with its path and rainfall. Identifying a bright line is one step; establishing what caused it takes dates, location and supporting information.
I can appreciate a glowing line without asking it to tell me something it doesn't contain. The interesting question is how that observation fits with the rest of the record. Scientists aren't simply holding a coral slice under a lamp and being handed a fully written weather report, however convenient that would be.
What a Hurricane Study Actually Found
A 2024 study by Aliyah Griffith and colleagues examined two reef-building coral species on the Florida Keys Reef Tract before and after Hurricane Irma. The researchers investigated skeletal density, upward growth and calcification at inner and outer reef locations. They worked with colonies sampled before the storm and collected micro-cores after it.
The results weren't a simple declaration that hurricanes make every coral grow less. The broad comparison found no pre- versus post-storm difference in the annual growth parameters, while analysis of year-to-year changes identified differences in skeletal density across groups. Comparable changes weren't found for the other two growth measures in that analysis.
I think that mixed result is worth keeping in the story. It shows why we need actual measurements instead of deciding in advance what a storm scar ought to look like. A change in one part of growth isn't evidence that every part changed in the same direction, and a result from those species and sites isn't a rule for all coral reefs.
It also makes the title's metaphor a bit more precise. We can investigate whether a storm is associated with a measurable legacy in coral growth. We don't need to turn that legacy into a literal recollection for the finding to be interesting.
The Reef Afterward May Be a Different Reef
There is another kind of history that doesn't require taking a core. If a storm removes some colonies and leaves others, the surviving community and the physical structure have changed. The next disturbance arrives at that changed reef, not at an untouched copy of the one that existed before.
That is an ecological legacy. A gap, a collapsed patch or a surviving large colony can influence what is possible afterward. It doesn't follow that the survivors learned a lesson from the storm, or that the new community is automatically stronger. Sometimes surviving means being lucky enough to occupy a less exposed spot.
This is where I want to be especially careful with DNA. The skeletal archives and hurricane studies discussed here don't establish that corals pass detailed storm memories to their offspring. Inheritance, changes within an organism's lifetime and a shift in which organisms survive are different processes. We can't slide between them just because memory makes an appealing headline.
My gardening comparison has limits for the same reason. I can learn from a damaged tomato plant because I am the one remembering what I did to it. That doesn't establish that the plant has stored my questionable transplant timing as an inherited warning. An analogy can help us ask a question without supplying the answer.
Storm Surge Isn't the Same Thing as a Wave
The National Hurricane Center defines storm surge as a storm-driven rise in water level above the predicted astronomical tide. Waves move on top of that elevated water, and the tide contributes to the total water level too. When we combine all of those into one vague idea of a big wave, we lose information that matters for coastal flooding.
Reefs can help dissipate wave energy as water passes over their structure. That doesn't make them a wall that stops every rise in sea level or guarantees safety during a hurricane. Coastal risk depends on the storm, water depth, reef condition and the shape of the coast, among other factors.
A USGS study of Hurricanes Hector and Lane in 2018 examined wave conditions across a reef off southern Molokaʻi. Measurements and modeling showed the reef substantially reduced waves moving toward the shoreline at the studied location. That is a concrete example of a reef's protective role, with an actual place and actual storm conditions attached.
I prefer that to a universal percentage applied to every coastline. The useful question is what a particular reef can do under particular conditions, and what changes if its structure is damaged. People planning for flooding need that level of detail. A reassuring sentence about nature protecting us can't substitute for it.
Living Coral and Reef Structure Aren't Identical Measures
It's possible to look at a patch of coral and focus entirely on whether living tissue remains. That is important, but it isn't the only thing that matters for coastal protection. The height, roughness and arrangement of the reef influence how water moves across it.
USGS research assessing damage from Hurricanes Irma and Maria examines the connection between changed reef conditions and coastal hazards. It is a reminder that losing structure has consequences beyond the appearance of the reef. Monitoring living cover and monitoring the physical framework answer related, but different, questions.
The distinction makes me think about the temptation to choose one encouraging number and let it stand for everything. A restoration project might report surviving fragments, while a different assessment asks whether a reef is rebuilding a complex structure. Both can be worthwhile measurements, but we need to keep their meanings attached.
I don't say that to make restoration sound hopeless. I say it because useful progress deserves to be described accurately. When we know what has improved, we also know what work remains instead of discovering later that we were celebrating a result nobody actually measured.
Recovery Needs Better Conditions, Not a Pep Talk
A reef dealing with a hurricane may also face excessive heat, disease or poor water quality. NOAA explains that bleaching occurs when stressed corals lose the symbiotic algae that help support them. A bleached coral is still alive, but its situation is more vulnerable, and recovery depends on the stress easing before the damage becomes fatal.
That means pale coral in a photograph isn't enough to diagnose exactly what happened. Exposed skeleton after breakage and living bleached tissue are different things. A storm history and a heat-stress history can also overlap, which makes the investigation more complicated than selecting the most dramatic recent event.
This part makes immediate sense to me as someone who gardens. If I want a struggling plant to recover, I need to pay attention to its conditions. Repeatedly moving it around and announcing that it should be resilient isn't a plan. I have occassionally had to remind myself that hovering is also not a nutrient.
Corals aren't tomatoes, and reef recovery involves processes I can't reproduce on my balcony. Still, the useful part of the comparison holds: recovery is a process supported by conditions, not a personality trait we can demand from a living thing. Calling a reef resilient doesn't remove the pressures acting on it.
A Broken Fragment Has a Chance, Not a Guarantee
NOAA notes that some broken coral fragments can survive and reattach under favorable conditions. Fragmentation can be a form of asexual reproduction for certain corals. That possibility is remarkable, but it doesn't turn storm damage into an automatic benefit.
A fragment that keeps moving, becomes buried or loses its living tissue may never establish itself. The word rubble covers material in very different conditions, and a pile of broken branches isn't proof that a new thriving colony is on its way. We need to know whether there is living tissue, a stable place to attach and a suitable environment.
NOAA's restoration program describes work that includes rescuing and stabilizing damaged corals. This involves trained teams assessing and handling the material, rather than visitors deciding to rearrange a reef. If I were visiting one, I'd leave broken coral where it was and follow the local guidance instead of treating it as a gardening project.
I find the patience of that work moving. Securing a living fragment creates a possibility; it doesn't let anyone skip the period of care and observation afterward. The hopeful photograph is a beginning, and the follow-up is how we find out what that beginning became.
What the Record Leaves Out
A core samples a particular part of a particular colony. A survey captures a place at a particular time. Combining those observations can reveal a great deal, but none of them justifies saying the ocean forgets nothing. Some evidence is lost, some is altered, and some was never recorded in a form we can recover.
There is also the problem of what survives long enough to be studied. A colony destroyed outright can't provide the same continuing growth record as one that remained alive. Looking only at survivors can tell us something valuable, while still leaving out an important part of the event.
This is why I like the combination of different methods. Growth records, water measurements, repeat surveys and storm histories can test one another. A convincing explanation becomes stronger when independent evidence fits together, not when we ask one especially beautiful sample to carry the entire argument.
That leaves plenty of room for wonder. I don't need a reef to be an infallible historian to be astonished that its skeleton can help researchers reconstruct environmental conditions from before modern monitoring. The gaps are part of what makes the investigation necessary.
The Part I'll Keep Thinking About
What draws me back to coral is the overlap between something alive right now and something carrying evidence of earlier conditions. We tend to divide those categories neatly: living things over here, historical objects over there. A growing colony makes that division feel less comfortable, in a useful way.
I started with my tomatoes because they have made me pay attention to consequences that persist after the obvious problem passes. The coral research takes that small observation somewhere much bigger. It asks how the past can remain measurable in growth, chemistry and the shape of a living community.
So yes, coral reefs can remember storms, if we're clear about what we mean. Their records can be physical, chemical and ecological, incomplete and still extraordinarily useful. They aren't promising that every injury makes them stronger, and I don't want to put that responsibility on them.
I'd rather ask what the evidence tells us and what conditions would give the reef a better chance next time. That feels like a more useful response to a living thing with a difficult history. It also leaves me with plenty to think about the next time I'm standing over a tomato plant, waiting for an explanation I'm still not going to get.
A coral-patterned serving platter would be a lovely excuse to bring those shapes to the table. Add a few little things to eat and I could happily keep talking about reefs well after everyone expected the science part of dinner to end.
Related Reads You Might Enjoy
The River Doesn’t Forget: How Cocaine Ended Up in Every Shrimp Tested
When Plastic Speaks: Coca-Cola, Corporate Power, and the Global Tide of Waste
The Sound of Extinction: How Disappearing Animals Take Silence With Them
The Whale That Would Not Let Death Pass: Why Humpbacks Keep Crashing Orca Hunts
Are Our Emotions Stored in Water? The Quiet Science (and Wonder) Behind It
The Coating on Your Organic Fruit: What Is Apeel, and Should You Be Concerned?
The Sound of Trees Crying: What Plants Really Do When They’re Stressed
Echoes Between Worlds: What Whales Might Teach Us About Alien Languages
The Emotional Lives of Fish: What Science Knows, and What We Ignore
Works Cited
USGS. Coral reef resistance to hurricane impacts: configuration and exposure. 1999.
NOAA Flower Garden Banks National Marine Sanctuary. Coral Cores: Ocean Timelines.
Australian Institute of Marine Science. Climate and environmental histories from coral.
USGS. Study: How Coral Reefs Shielded Hawaiian Coastlines Against 2018 Hurricanes.
