The story of corals in the modern age on this planet is one of near-total despair. I’ve done several stories on corals and have spent many hours diving reefs around the world, from the Mesoamerican Reef in Belize to the unbelievably robust and dazzling reefs in Indonesia. There are still some incredible places where corals survive, but they are becoming fewer and farther between. I don’t want to get too deep into all the statistics, but suffice it to say: scientists estimate that we have already lost about half of the world’s corals since the 1950s, and that number could rise to as much as 90 percent by 2050 if current rates of bleaching and die-offs continue.
What’s crazy is that we still don’t completely understand corals, or exactly why they are dying. We know that corals are symbionts with microscopic algae called zooxanthellae (pronounced zo-zan-THEL-ee). The corals provide cover, a place to live, and nutrients for the algae. In return, the algae provide sugars and oxygen through photosynthesis, fueling coral growth and reef-building. But when the planet warms, or when waters become too acidic, the relationship often collapses. The algae either die or flee the coral. Without that steady food source—what one scientist I interviewed for this story called “a candy store”—corals turn ghostly white in a process known as bleaching. If stressful conditions persist, they starve and die.
The Great Barrier Reef, once Earth’s largest living structure, has suffered five mass bleaching events since 1998, and vast stretches have become little more than graveyards of coral skeletons. The scale of this ecological disaster is almost unimaginable. And so scientists around the world are in a race to figure out what’s happening and how to at least try to slow down the bleaching events sweeping through nearly every major reef system.
An image of Montipora coral polyps taken with the BUMP. Each polyp has a mouth and a set of tentacles and the red dots are individual microalgae residing inside the coral tissue. (Photo: Or Ben-Zvi)
One place where scientists are making small strides is at the Jaffe Lab, which I visited with my colleague Tod Mesirow and where researchers like Dr. Jaffe and Dr. Or Ben-Zvi have developed a new kind of underwater microscope that allows them to get close enough to corals to actually see the algae in action.
This is no small feat. Zooxanthellae are only about 5–10 microns across, about one-tenth the width of a human hair, and invisible to the naked eye. With the new microscope and camera system, though, they can be seen in astonishing detail. The lab has captured unprecedented behavior, including corals fighting with each other for space, fusing together, and even responding to invading algae.
When I first reported on this imaging system years ago, it was still in its early stages. At the time, it was known as the BUM for Benthic Underwater Microscope. Since then, the Scripps team has added a powerful new capability: a pulsing blue light that lets them measure photosynthesis in real time. They call it pulse amplitude modulated light or PAM, and so now the system is known as the BUMP.
A field deployment of the BUMP in the Red Sea, where local corals were imaged and measured. (Photo: Or Ben-Zvi)
Here’s how it works: blue excitation light stimulates the algae’s chlorophyll, which then re-emits some of that energy as red fluorescence. By tracking how much of this red fluorescence is produced, researchers can calculate indices of photochemical efficiency, essentially how well the algae are converting light into energy for photosynthesis. This doesn’t give a direct count of sugars or photons consumed, but it does provide a reliable window into the health and productivity of the algae, and by extension, the coral itself.
What’s crucial is that all of this imaging takes place in situ—right in the ocean, on living reefs—rather than in the artificial setting of an aquarium or laboratory.
New tools are essential if we’re going to solve many of our biggest problems, and it’s at places like Scripps in California where scientists are hard at work creating instruments that help us see the world in entirely new ways. “There’s so much to learn about the ocean and its ecosystems, and my own key to understanding them is really the development of new instrumentation,” says Jaffe.
Dr. Ben-Zvi gave us a demonstration of how the system works in an aquarium holding several species of corals, including Stylophora, a common collector’s coral. She showed us the remarkable capabilities of the camera-microscope, which illuminated and brought into crisp focus the tiny coral polyps along with their algal partners. On the screen we watched them in real time, tentacles waving as they absorbed the flashes of light from the BUMP, appearing, almost, as if they were dancing happily.
What this new tool allows scientists to do is determine whether corals may be under stress from factors like warming seas, pollution, or disease. Ideally, these warning signs are detected before the corals expel their zooxanthellae and bleach. Researchers are also learning far more about the everyday behavior of corals: something rarely studied in situ, directly in the ocean.
That in-their-native-environment aspect of the work is crucial, because corals often behave very differently in aquariums than they do on wild reefs. That’s where this microscope promises to be a powerful tool: offering insights into how corals really live, fight, and respond to stress.
Of course, what we do once we document a reef under stress is another matter. Dr. Ben-Zvi suggests there may be possibilities for remediation, though she admits it’s difficult to know exactly what those are. Perhaps reducing pollution, limiting fishing, or cutting ship traffic in vulnerable areas could help. But given that we seem unable—or unwilling—to stop the warming of the seas, these measures can feel like stopgaps rather than solutions. Still, knowledge is the foundation for any action, and this new tool is a breakthrough for coral imaging. If deployed widely, it could generate an invaluable dataset for researchers around the globe. The scientists behind it even hope to build multiple systems, perhaps commercializing them, to vastly expand the reach of this kind of monitoring.
But even Jaffe concedes it may already be too late: “Could a world exist without corals? Yeah, I think so,” he said. “It would be sad, but it’s going that way.”
All the same, the images the tool produces are breathtaking, and at the very least, they might jolt people into realizing that this is a crisis worth trying to solve. If we can’t, then future generations will be left only with these hauntingly beautiful images to remember the diverse and gorgeous animals that once flourished along the edges of the sea.
A healthy coral reef in Indonesia (Photo: Erik Olsen)
Is that valuable? Yes, but not nearly as valuable as saving the living reefs themselves. Dr. Jaffe told us,
“I’m on a mission to help people feel empathy toward the creatures of the sea. At the same time, we need to learn just how beautiful they are. For me, the combination of beauty and science has been at the heart of my life’s work.”
His words capture the spirit of this research. The underwater microscope isn’t just a scientific instrument. It’s a lens into a hidden world, one that may inspire people to care enough to act before it’s gone. Too bad the clock is ticking so fast.
Flasks of Asparagopsis taxiformis growing at Scripps Institution of Oceanography. Researchers are studying this red seaweed for its potential to slash methane emissions from cattle when added in small amounts to their feed. (Photo: Erik Olsen)
Inside a long, brightly lit basement lab at the Scripps Institution of Oceanography at UC San Diego, a large aquarium filled with live corals sits against the wall, the vibrant shapes and colors of the coral standing out against the otherwise plain white surroundings. Nearby, in a side alcove, dozens of glass flasks bubble with aerated water, each holding tiny crimson clusters of seaweed swirling in suspension, resembling miniature lava lamps. These fragile red fragments, born in California and raised under tightly controlled conditions, are part of a global effort to harness seaweed to fight climate change.
Cattle and other ruminant livestock are among the largest contributors to methane emissions worldwide, releasing vast amounts of the gas through digestion and eructation. Burps, not farts. The distinction is not especially important, but it matters because critics of climate science often mock the idea of “cow farts” driving climate change. In reality, the methane comes primarily from cow burps, not flatulence.
But I digress.
Cattle at Harris Ranch in California’s Central Valley, one of the largest beef producers in the United States. Livestock operations like this are a major source of methane emissions, a greenhouse gas more than 80 times as potent as carbon dioxide over a 20-year period. (Photo: Erik Olsen)
Globally, livestock are responsible for roughly 14 percent of all human-induced greenhouse gases, with methane from cattle making up a significant portion of that total. The beef and dairy industries alone involve more than a billion head of cattle, producing meat and milk that fuel economies but also generating methane on a scale that rivals emissions from major industrial sectors. Because methane is so potent, trapping more than 80 times as much heat as carbon dioxide over a 20-year period, the livestock industry’s footprint has become a central focus for climate scientists searching for solutions.
Enter Jennifer Smith and her colleagues at the Smith Lab at Scripps in beautiful La Jolla, California. Their team is tackling urgent environmental challenges, from understanding coral die-offs to developing strategies that reduce greenhouse gas emissions, among them, the cultivation of seaweed to curb methane from cattle.
The seaweed species is Asparagopsis taxiformis. Native to tropical and warm temperate seas and found off the coast of California, in fact right here off the coast in San Diego, it produces natural compounds such as bromoform that interfere with the microbes in a cow’s stomach that generate methane gas, significantly reducing the production of methane and, of course, it’s exhalation by the animals we eat. It turns out the seaweed, when added to animal feed can be very effective:
Asparagopsis taxiformis, commonly known as red sea plume, a tropical red algae being studied for its ability to cut methane emissions from cattle. (Photo: Wikipedia)
“You need to feed the cows only less than 1% of their diet with this red algae and it can reduce up to 99% of their methane emissions,” said Dr. Or Ben Zvi, an Israeli postdoctoral researcher at Scripps who studies both corals and seaweeds.
Trials in Australia, California, and other regions have shown just how potent this seaweed can be. As Dr. Ben Zvi indicated, even at tiny doses, fractions of a percent of a cow’s feed, other studies have shown that it can reduce methane by 30 to 90 percent, depending on conditions and preparation. Such results suggest enormous potential, but only if enough of the seaweed can be produced consistently and sustainably.
“At the moment it is quite labor intensive,” says Ben Zvi. “We’re developing workflows to create a more streamlined and cost-effective industry.”
Which explains to bubbling flasks around me now.
Scripps Institution of Oceanography at UC San Diego (Photo: Erik Olsen)
The Smith lab here at Scripps studies every stage of the process, from identifying which strains of Asparagopsis thrive locally to testing how temperature, light, and carbon dioxide affect growth and bromoform content. Dr. Ben Zvi is focused on the life cycle and photosynthesis of the species, refining culture techniques that could make large-scale cultivation possible. At Scripps, environmental physiology experiments show that local strains grow best at 22 to 26 °C and respond well to elevated CO₂, information that could guide commercial farming in Southern California.
The challenges, however, are considerable. Wild harvesting cannot meet demand, and cultivating seaweed at scale requires reliable methods, stable yields, and affordable costs. Bromoform content varies widely depending on strain and growing conditions, so consistency remains an issue. Some trials have noted side effects such as reduced feed intake or excess mineral uptake, and long-term safety must be established since we’re talking about animals that we breed and raise to eat.
“It’s still a very young area, and we’re working on the legislation of it,” says Ben Zvi. “We need to make it legal to feed to a cow that eventually we either drink their milk or eat their meat. We need for it to be safe for human consumption.”
Dr. Or Ben Zvi (Photo: Erik Olsen)
And, of course, large-scale aquaculture raises ecological questions, from nutrient demands and pollution to the fate of volatile compounds like bromoform.
To overcome these obstacles, collaborations are underway. UC San Diego and UC Davis have launched a pilot project under the UC Carbon Neutrality Initiative to test production methods and carbon benefits. In 2024, CH4 Global, a U.S.-based company with operations in New Zealand and Australia that develops seaweed feed supplements to cut livestock methane, partnered with Scripps to design cultivation systems that are efficient, inexpensive, and scalable. Within the Smith Lab, researchers are continuing to probe the biology of Asparagopsis, mapping its genetics, fine-tuning its culture, and testing ways to maximize both growth and methane-suppressing compounds.
At a time when university-based science faces immense pressures, the Smith Lab at Scripps provides a glimpse of research that is making a real impact. The coral tanks against the wall belong to another project at the lab, and we have another story coming soon about the research that readers will find very interesting, but the bubbling flasks in the alcove reveal how breakthroughs often start with small details. In this case, the discovery that a chemical in a widely available seaweed could have such a dramatic, and apparently harmless, effect on the methane that animals make in their guts. These modest but powerful steps are shaping solutions to global challenges, and California, with its wealth of scientific talent and institutions, remains at the forefront. It is one of many other stories we want to share, from inside the labs to the wide open spaces of the state’s natural landscapes.
The ocean covers about 70 percent of Earth’s surface and holds 96 percent of its water. But because it’s saturated with salt, it isn’t drinkable. Sailors have known this for centuries, and that’s a profound challenge for California, with more than 800 miles of coastline and a history of drought that has persisted for over two decades despite occasional relief from heavy rains.
Remember those rains?
The atmospheric rivers of 2024 in California briefly filled reservoirs and restored snowpack, but drought has already returned to parts of the state, underscoring the state’s precarious water future and fueling renewed debate over desalination as a long-term water solution.
The Los Angeles Rifer flows high following atmospheric river storms in 2024 (Photo: Erik Olsen)
Several regions facing severe drought have turned to desalination with notable success. Israel now supplies up to 40 percent of its domestic water through desalination and is widely recognized as a global leader in technological innovation. In the Gulf, countries like Saudi Arabia, the United Arab Emirates, Kuwait, and Qatar depend heavily on desalinated water, with the region producing roughly 40 percent of the world’s supply of desal. Saudi Arabia’s Ras Al-Khair plant, for example, is the largest hybrid desalination facility in the world. Australia has also invested heavily, with Adelaide’s desalination plant able to provide up to half of the city’s water and ramping up to full capacity during the 2024–2025 drought.
By contrast, California, the world’s fourth-largest economy, continues to struggle with recurring droughts despite some relief from those recent rains.
Many new projects are underway to recycle and store water, but desalination remains an important option that could play a larger role in how California manages supplies for its residents and farmers. For now, the state has only a handful of desalination plants, with just two operating at significant scale, leaving California far behind global leaders.
The Piggyback Yard rail site in Los Angeles, long used for freight operations, is now at the center of a proposal to transform the space into a massive stormwater capture and storage project. (Photo: Erik Olsen)
California will keep bouncing between wet and dry years, and that reality has pushed seawater and brackish-water desalination from a thought experiment into a real, if specialized, tool. It’s a big deal: The promise is reliable “drought-proof” supply. The tradeoffs are clear: high costs, heavy energy demands, and the challenge of careful siting. California has pushed the frontier of desalination technology, but it remains far from being an integral or dependable part of the state’s supply. Many observers doubt it ever will be.
But let’s take a look at where we are.
Desalination is already part of daily life in a few places. The 50-million-gallon-per-day Claude “Bud” Lewis Carlsbad Desalination Plant supplies roughly a tenth of the San Diego region’s potable demand, making it the largest seawater desalination facility in the United States. Water from Carlsbad is reliable during drought, but that reliability carries a premium: Recent public figures put its delivered cost in the low-to-mid $3,000s per acre-foot, higher than most imported supplies when those are plentiful. Even advocates frame the key tradeoff as price and energy intensity in exchange for certainty.
Rules matter as much as membranes. Since 2015, California has required new ocean desal plants to use the best available site, design, technology, and mitigation measures to minimize marine life mortality at intakes and to limit brine impacts at outfalls. These standards make facilities gentler on the ocean and they shape where plants can be built and what they cost. But it’s complicated.
The permitting bar is real, some say too onerous. In May 2022 the California Coastal Commission unanimously denied the proposed Huntington Beach seawater desalination plant after staff raised concerns about high costs, harm to marine life from an open-ocean intake, exposure to sea-level rise, and a lack of demonstrated local demand. That decision did not end desalination, but it clarified where and how it can pencil out. The same year, the Commission unanimously approved the smaller Doheny project in Dana Point because it uses subsurface intake wells and showed stronger local need and siting.
The Seawater Desalination Test Facility in Port Hueneme, Ventura. (Photo: John Chacon / California Department of Water Resources)
Doheny is frequently described as a late-2020s project, but its official timeline has slipped as partners and financing have taken longer to come together. That’s so California. The South Coast Water District has projected completion and operations in 2029, with key procurement milestones running through 2025. Given California’s regulatory climate, I’d say these dates are optimistic rather than bankable.
Elsewhere on the coast, the California American Water project for the Monterey Peninsula cleared a major hurdle in November 2022. Designed to add about 4.8 million gallons per day and pair with recycled water to replace over-pumping groundwater (a huge issue), it underscored desal’s role where other options are limited. In August 2025, the CPUC projected a 2050 supply deficit of 815 million gallons per year and cleared the way for construction to begin by year’s end. So, yeah. We’ll see.
Project site map of the Doheny Ocean Desalination Project (South Coast Water District)
Desalination is not only ocean-sourced. Several California systems quietly run on brackish water, which is less salty and cheaper to treat than seawater. Antioch’s brackish plant on the San Joaquin River is designed for about 6 million gallons per day to buffer the city against salinity spikes during drought. It was slated to come online this year, but operations have yet to begin (at least, I could not find any new info to this effect). Up the coast, Fort Bragg installed a small reverse-osmosis system in 2021 to deal with high-tide salt intrusion in the Noyo River during critically low flows, and it has piloted wave-powered desal buoys for emergency resilience.
Santa Barbara’s Charles E. Meyer plant was reactivated in 2017 after years in standby and now functions as a reliability supply the city can dial into. In 2024 it contributed a meaningful slice of deliveries.
These are targeted, local solutions, not silver bullets, and that is the point.
Energy remains the biggest driver of desalination costs. Even with modern technology cutting usage to 2.5 to 4 kilowatt-hours per cubic meter, desal still requires far more power and therefore higher expense than water recycling or imported supplies. Beyond cost, desalination also brings added challenges, from greenhouse gas emissions tied to electricity use to the disposal of concentrated brine back into the ocean.
Santa Barbara’s Charles E. Meyer plant (City of Santa Barbara)
But the reality today is that the biggest additions to statewide water supply are coming from large-scale potable reuse, aka recycling. San Diego’s Pure Water program begins adding purified water to the drinking system in 2026 and scales toward about 83 million gallons per day by 2035. Metropolitan Water District’s Pure Water Southern California is planning up to roughly 150 million gallons per day at full build-out. These projects do not replace desal everywhere, but they change the calculus in big metro areas by creating local, drought-resilient supplies with generally lower energy and environmental footprints.
With most desalination projects carrying steep costs, success may hinge on innovation. Several new approaches now being tested in California waters are showing early promise. In 2025, OceanWell began testing underwater desalination pods in a reservoir near Malibu. These cylindrical units are designed to test how membranes perform when microorganisms are present in the water, since bacteria and algae can grow on the surfaces and form biofilms that clog the system.
A drawing of OceanWell’s underwater desalination pod system (OceanWell)
The longer-term vision is “water farms” made up of subsea pods tethered 1,300 feet down, where natural hydrostatic pressure does much of the work. Each pod could produce up to a million gallons of fresh water per day with roughly 40 percent less energy than a conventional onshore plant. Because the brine would be released gradually at depth, the approach could also reduce ecological impacts. OceanWell has said its first commercial-scale project, called Water Farm 1, could be operating by 2030 if tests and permitting go as planned. It’s interesting, for sure, but in the end, we’re talking long-shot here.
Big picture, desalination works best as a specialty tool—it’s not the answer everywhere, but it can be a game-changer in the right spots. Think coastal towns with little groundwater, islands or peninsulas with fragile aquifers, or inland areas that get hit with salty water now and then. California’s rules now push projects toward gentler ocean intakes and better brine disposal, but the real strategy is a mix: conservation, stormwater capture, groundwater banking, recycled water, and just the right amount of desal. Those huge atmospheric river storms are not predictable. Who knows if we’ll get another next year or the year after that? The next drought will come, and the communities that invested in a full toolkit will be the ones that hold up the best.
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It’s time for California to put people back in the deep. A human-occupied submersible belongs in California waters, and we’ve waited long enough.
For decades, the state had a strong human-occupied submersible presence, from Navy test craft in San Diego to long-serving civilian science HOVs like the Delta. Those vehicles have been retired or relocated, leaving the West Coast without a single home-based, active human-occupied research submersible (I am not counting OceanGate’s Titan sub for numerous reasons, like the fact it was based in Seattle, but foremost is it was not “classed,” nor was it created for scientific use). Restoring that capability would not only honor California’s legacy of ocean exploration but also put the state back at the forefront of direct human observation in the deep sea. The time has come.
Side note: I’ve had the rare privilege of diving beneath the waves in a submersible three times in three different subs, including one descent to more than 2,000 feet with scientists from the Woods Hole Oceanographic Institution. Without exaggeration, it stands among the greatest experiences of my life.
The United States once had a small fleet of working research HOVs. Today it has essentially one deep-diving scientific HOV in regular service: Alvin, operated by Woods Hole Oceanographic Institution (WHOI) for the National Deep Submergence Facility. Alvin is magnificent, now upgraded to reach 6,500 meters, but it is based on the Atlantic (in Massachusetts) and scheduled years in advance at immense cost.
The human-occupied submersible Alvin surfaces during the 2004 “Mountains in the Sea” Expedition, returning from a dive to explore deep seamount habitats teeming with corals, sponges, and other rarely seen marine life. (Photo: NOAA, Public Domain)
It helps to remember how we got here. The Navy placed Alvin in service in 1964, a Cold War investment that later became a pillar of basic research, investigating hydrothermal vents, shipwrecks and underwater volcanoes, among many, many other accomplishments. Over six decades of safe operations, Alvin has logged thousands of dives and undergone multiple retrofits, each expanding its depth range. Now rated to 6,500 meters, it can reach 98 percent of the ocean floor. WHOI’s partnership model with the Navy and universities shows exactly how public investment and science can reinforce each other. But Alvin is based on the East Coast: all that capability, history, and expertise is thousands of miles away. California needs its own Alvin. Or something even better…and perhaps cheaper. Though by cheaper I do not mean less safe.
For a time, California actually had multiple HOVs. The Navy fielded sister craft to Alvin, including Turtle and Sea Cliff. Both Turtle and Sea Cliff spent their careers with Submarine Development Group ONE in San Diego. Turtle was retired in the late 1990s, and Sea Cliff, launched in 1968 and later upgraded for greater depths, also left service by the end of that decade, ending the Navy’s home-ported HOV presence on the West Coast.
On the Atlantic side, Harbor Branch’s two Johnson Sea Link HOVs supported science and search-and-recovery work for decades before the program ended in 2011 due to funding constraints and shifting research priorities. I’ve interviewed renowned marine biologist Edith Widder several times, and she often speaks about how pivotal her dives in the Johnson Sea Link submersibles were to her career studying animal bioluminescence.
“Submersibles are essential for exploring the planet’s largest and least understood habitat, ” Widder told me. “A human-occupied, untethered submersible offers an unmatched window into ocean life, far surpassing what remotely operated vehicles can provide. ROVs, with their noisy thrusters and blazing lights, often scare away marine animals, and even the most advanced cameras still can’t match the sensitivity of the fully dark-adapted human eye for observing bioluminescence.”
In the central Pacific, the University of Hawaiʻi’s HURL operated Pisces IV and V for much of the 2000s and 2010s, then suspended operations amid funding and ship transitions. Through attrition and budget choices, the working U.S. fleet shrank from a handful to essentially one deep-diving research HOV today.
Manned submersibles are costly to build and operate, and they demand specialized crews, maintenance, and support ships or platforms. It’s easy to list reasons why California shouldn’t invest in a new generation of human-occupied subs. But that mindset has kept us out of the deep for far too long. It’s time to turn the conversation around and recognize why having one here would be a transformative asset for science, education, and exploration.
The Seacliff and Turtle submersibles (Photo: U.S. Naval History and Heritage Command photo. Public Domain)
California’s own human-occupied sub legacy is short, but notable. In addition to the Navy submersibles noted above, the Delta submersible, a compact, ABS-class HOV rated to about 1,200 feet, operated from Ventura and later Moss Landing, supporting dozens of fishery and habitat studies from the Southern California Bight to central California. Built by Delta Oceanographics in Torrance, Delta dives in the mid-1990s produced baseline data that still underpin rockfish management, MPA assessments, and predictive habitat maps. The sub’s ability to place scientists directly on the seafloor allowed for nuanced observations of species behavior, habitat complexity, and human impacts that remote tools often miss. Many of these datasets remain among the most detailed visual records of California’s deeper reef ecosystems.
The Monterey Bay Aquarium Research Institute (MBARI) operates a world-class research fleet with a robust remotely operated vehicle (ROV) program, but no human-occupied vehicle—a strategic decision the institute made years ago in favor of robotics over direct human dives. (Photo: Erik Olsen)
In the late 1990s, the program shifted north to Moss Landing, where it was operated in partnership with the Monterey Bay Aquarium Research Institute (MBARI) and other institutions. At the time, MBARI was still in the early years of exploring human-occupied vehicles, like Bruce Robison’s experience piloting the Deep Rover HOV in Monterey Canyon in 1985. To many at MBARI, human occupancy in submersibles began to seem more like a luxury than a necessity. If the goal was to maximize scientific output and engineering innovation, remotely operated vehicles offered longer bottom times, greater payload capacity, and fewer safety constraints. That realization drove MBARI to invest heavily in ROV technology, setting the stage for a long-term move away from human-occupied systems.
Which leads us to the present moment: California’s spectacular coast faces mounting environmental threats, just as public interest in ocean science wanes. And yet, we have no human-occupied research submersible, no way for scientists or the public to directly experience the deep ocean that shapes our state’s future.
The Delta submersible, once a workhorse of California’s deep-sea research with over 5,800 dives, operated from Ventura and later Moss Landing between the 1980s and 2000s. Sold in 2011 in a non-functional state, it remains out of service—symbolizing the end of the state’s home-ported human-occupied submersible era.
Look, robots are incredible. MBARI’s ROVs and AUVs set global standards, and they should continue to be funded and expanded. But if you talk to veteran deep-sea biologists and geologists, they will tell you that being inside the environment changes the science.
Dr. Adam Soule, chief scientist for Deep Submergence at the Woods Hole Oceanographic Institution (WHOI) agrees, “Having a human presence in the deep sea is irreplaceable. The ability for humans to quickly and efficiently process the inherently 3D world around them allows for really efficient operations and excellent sampling potential. Besides, there is no better experience for inspiring young scientists and for ensuring that any scientist can get the most out of unmanned systems than immersing themselves in the environment.”
Some of our most prominent voices are also speaking out about the need to explore the ocean. I recently produced an hour-long episode of the PBS science program NOVA and one episode was about the new generation of submersibles being built right now by companies like Florida-based Triton Submarines. I had the privilege of talking to filmmaker and ocean explorer James Cameron, who was adamant that human participation in ocean exploration is critical to sustaining public interest and political will.
“The more you understand the ocean, the more you love the ocean, the more you’re fascinated by it, and the more you’ll fight to protect it,” Cameron told me.
The author with James Cameron in front of his submersible the Deepsea Challenger. (Erik Olsen)
Human eyes and brains pick up weak bioluminescence out of the corner of vision, pivot to follow a squid that just appeared at the edge of a light cone, or decide in the moment to pause and watch a behavior a diving team has never seen before. NOAA’s own materials explain the basic value of HOVs this way: you put scientists directly into the natural deep-ocean environment, which can improve environmental evaluation and sensory surveillance. Presence is a measurement instrument.
California is exactly where that presence would pay off. Think about Davidson Seamount, an underwater mountain larger than many national parks, added to the Monterey Bay National Marine Sanctuary because of its ancient coral gardens and extraordinary biodiversity. We know this place mostly through ROVs, and we should keep using them, but a California HOV could carry sanctuary scientists, MBARI biologists, and students from Hopkins Marine Station or Scripps into those coral forests to make fine-scale observations, sample with delicacy, and come home with stories that move the public. Put a student in that viewport and you create a career. Put a donor there and you create a program.
A time-lapse camera designed by MBARI engineers allowed researchers to observe activity at the Octopus Garden between research expeditions. (Photo: MBARI)
Cold seeps and methane ecology are another natural fit. Off Southern California and along the borderlands there are active methane seep fields with complex microbial and animal communities. Recent work near seeps has even turned up newly described sea spiders associated with methane-oxidizing bacteria, a striking reminder that the deep Pacific still surprises us. An HOV complements ROV sampling by letting observers linger, follow odor plumes by sight and instrument, and make rapid, in-situ decisions about fragile communities that are easy to miss on video. That kind of fine-grained exploration connects directly to California’s climate priorities, since methane processes in the ocean intersect with carbon budgets.
There are practical use cases all over the coast. A California HOV could support geohazard work on active faults and slope failures that threaten seafloor cables and coastal infrastructure. It could conduct pre- and post-event surveys at oil-and-gas seep sites in the Santa Barbara Channel to ground-truth airborne methane measurements. It could document deep-water MPA effectiveness where visual census by divers is impossible. It could make repeated visits to whale falls, oxygen minimum zone interfaces, or sponge grounds to study change across seasons.
An autonomous underwater craft used to map DDT barrels on the seafloor off California. (Photo: Scripps Institution of Oceanography at U.C. San Diego)
It could also play a crucial role in high-profile discoveries like the recent ROV surveys that revealed thousands of corroding barrels linked to mid-20th-century DDT dumping off Southern California. Those missions produced stark imagery of the problem, but a human-occupied dive would have allowed scientists to make on-the-spot decisions about barrel sampling, trace-chemical measurements, and sediment core collection, as well as to inspect surrounding habitats for contamination impacts in real time. The immediacy of human observation could help shape quicker, more targeted responses to environmental threats of this scale.
And it’s not just the seafloor that matters. Some of the most biologically important parts of the ocean lie well above the bottom. The ocean’s twilight zone, roughly 200 to 1,000 meters deep, is a vast, dimly lit layer that contains one of the planet’s largest reservoirs of life by biomass. (My dive with WHOI was done to study the ocean’s twilight zone). Every day, trillions of organisms participate in the planet’s largest migration, the diel vertical migration, moving up toward the surface at night to feed and returning to depth by day. This zone drives global carbon cycling, supports commercial fish stocks, and is home to remarkable gelatinous animals, squid, and deepwater fishes that are rarely seen in situ.
Launching the Triton 3300/3 (Photo: Erik Olsen)
The Triton 3300/3’s 1,000-meter depth rating (I’ve been in one twice) puts the entire twilight zone within reach, enabling direct observation of these daily movements, predator-prey interactions, and delicate species that often disintegrate into goo in nets. Human presence here allows scientists to make real-time decisions to follow unusual aggregations, sample with precision, and record high-quality imagery that captures how this midwater world works, something uncrewed systems alone rarely match.
It could even serve as a classroom at depth for carefully designed outreach dives, giving educators footage and first-person accounts that no livestream can quite match. Each of these missions is stronger with people on site, conferring, pointing, deciding, and noticing.
While Monterey Bay would be a natural fit because of MBARI, Hopkins, and the sanctuary’s deepwater treasures, Southern California could be just as compelling. Catalina Island, with its proximity to submarine canyons, coral gardens, and cold seeps of the Southern California Bight, offers rich science targets and the existing facilities of USC’s Wrigley Marine Science Center. Los Angeles or Long Beach would add the advantage of major port infrastructure and a vast urban audience, making it easier to combine high-impact research with public tours, donor events, and media outreach. And San Diego with its deep naval history, active maritime industry, Scripps Institution of Oceanography, and proximity to both U.S. and Mexican waters, could serve as a southern hub for exploration and rapid response to discoveries or environmental events. These regions could even share the vehicle seasonally: Monterey in summer for sanctuary work, Catalina/LA or San Diego in winter for Southern California Bight missions, spreading both benefits and funding responsibility.
The author in front of the Triton 3300/3 in the Bahamas (Photo: Erik Olsen)
For budgeting, a proven benchmark is the Triton 3300/3, a three-person, 1,000-meter (3,300-foot) human-occupied vehicle used widely in science and filming. New units are quoted in the four to five million dollar range, with recent builds coming in around $4–4.75 million depending on specifications. Beyond the vehicle, launch and recovery systems such as a 25–30-ton A-frame or LARS and the deck integration required for a suitable support ship can run into the high six to low seven figures. Modern acrylic-sphere subs like the Triton are designed for predictable, minimized scheduled maintenance, but budgets still need to account for annual surveys, battery service, insurance, and ongoing crew training. Taken together, a California-based HOV program could be launched for an initial capital investment of roughly $6–7 million, with operating budgets scaled to the number of missions each year. So, not cheap. But doable for someone of means and purpose and curiosity. See below.
Who would benefit if California restored this capability? Everyone who already works here. MBARI operates a world-class fleet of ROVs and AUVs but has no resident HOV. Scripps Institution of Oceanography, Hopkins Marine Station, and USC’s Wrigley Marine Science Center train generations of ocean scientists who rarely get the option to do HOV work without flying across the country and waiting for a slot. NOAA and the sanctuaries need efficient ways to inspect resources and respond to events. A west-coast human-occupied research submersible based in Monterey Bay, Catalina, Los Angeles, or San Diego would plug into ship time on vessels already here, coordinate with ROV teams for hybrid dives, and cut mobilization costs for Pacific missions.
A new Triton 660 AVA submersible slips into the turquoise waters of the Bahamas, beginning its first voyage. Built for dives to 660 feet (200 meters), it offers passengers a front-row seat to reefs, shipwrecks, and marine life far beyond normal scuba limits, making it an ideal draw for high-end tourism. (Photo: Erik Olsen)
What would it take? A benefactor and a compact partnership. California has the donors (hello, curious billionaires!), companies, and public-private institutions to do this right. A philanthropic lead gift could underwrite acquisition of a proven, classed HOV and its support systems, while MBARI, Scripps, or USC could provide engineering, pilots, and safety culture within the UNOLS standards that govern HOV operations. No OceanGates. Alvin’s long record shows the model. Add a state match for workforce and student access, and a sanctuary partnership to guarantee annual science priorities, and you have a durable program that serves research, stewardship, and public engagement.
Skeptics will say that robots already do the job. They do a lot of it. They do not do all of it. If the U.S. is content to have only one deep research HOV based on the opposite coast, we will forego the unique perspectives and serendipity that only people bring, and we will keep telling California students to wait their turn or watch the ROV feed from their laptops or phones. California can do better. We did, for years, when the Delta sub spent long seasons quietly counting fish and mapping habitats off Ventura and the Channel Islands. Then that capability faded. If we rebuild it here, we restore a missing rung on the ladder from tidepools to trenches, and we align the state’s science, climate, and education missions with a tool that is both a laboratory and a conversion experience.
The author at more than 2000 feet beneath the surface of the ocean. (Photo: Erik Olsen)
Start with a compact, 1,000-meter-class HOV that can work daily in most of California’s shelf and slope habitats. Pair it with our ROVs for tandem missions and cinematography of the sub and its occupants in action. Commit a share of dives to student and educator participation, recorded and repackaged for museums and broadcast. Reserve another share for rapid-response science at seeps, landslides, unusual biological events, or contamination crises like the DDT dumpsite. Build a donor program around named expeditions to Davidson Seamount, Catalina’s coral gardens, and the Channel Islands. Then, if the community wants to go deeper, plan toward a second vehicle or an upgrade path. The science is waiting. The coast is ready. And the case is clear. California should restore its human-occupied submersible fleet.
Recently, I wrote a more personal essay than I usually would, one in which I reflected on the state of overfishing globally and the broader exploitation of our oceans.I hoped to draw attention to the new National Geographic documentary Oceans, featuring David Attenborough, which paints a broad and dire picture of the heath of the oceans and global fisheries…and it didn’t even cover deep sea mining which is a whole other megillah.
I’ve been following ocean conservation issues for decades, I’ve done numerous stories on the subject for major publications, and I’m deeply aware of the many threats facing the sea. These challenges extend to human society, too. Climate change, pollution, political instability, and species loss are just a few of the crises that fill our doom-scrolling feeds every day.
But not everything is lost.
Vermilion rockfish. (Photo: Robert Lee/NOAA)
Despite the scale of these problems, there are reasons for hope. Around the world, we are beginning to better manage some of our natural resources. There is growing awareness about how to extract from the planet in ways that do not destroy it. Slowly, we are learning how to sustain a growing, hungry population without collapsing the ecosystems we rely on. At least, that’s the hope. If you look around a bit, there are a few positive signs. I cited California’s Marine Protected Area program, but there are others.
Another particularly hopeful development is unfolding just off the coast of California.
The story of groundfish in California and the West Coast is one of collapse, struggle, rebirth, as well as evolving policy. Following passage of the Magnuson-Stevens Fishery Conservation and Management Act in 1976, which was supposed to help the fishery by banning foreign commercial fishing, between 1976 and 1979, the West Coast groundfish fleet tripled in size, growing from about 300 to nearly 1,000 vessels. New technologies made those boats far more effective. By the mid-1980s, about half the fleet could electronically track their fishing paths and return to the same productive grounds again and again. Sophisticated fishfinders like the “Chromascope” gave vessels an unprecedented edge.
A fishermen tending a groundfish trawl net off the coast of Oregon in 2019. (Photo: John Rae/NOAA)
Groundfish catch soared. In 1976, domestic harvests (excluding Pacific whiting) totaled around 57,000 tons. By 1982, that number had more than doubled to 119,000 tons. Rockfish, barely counted in the earlier fishery, made up more than 40,000 tons of the catch by that year alone.
But the science hadn’t caught up.
Fishery managers at the time didn’t fully understand how slowly groundfish grow, how long they live, or how vulnerable they are to overfishing. As a result, catch limits were set too high. The boom quickly gave way to collapse.
In the late 1990s and early 2000s, rockfish, bocaccio, Pacific ocean perch and other deep‑dwelling species teetered on collapse. Overfishing, excessive trawling, and habitat damage from bottom nets stripped populations across hundreds of miles of West Coast shelf. Regulators sounded the alarm and declared fishery disasters.
Sea bass in a California kelp forest (Photo: Erik Olsen)
Kenneth Weiss wrote in the Los Angeles Times, “Behind the sweeping action is a reluctant realization that the vast ocean has limits and cannot, as was long believed, provide an inexhaustible supply of fish.” Ya think?
To halt the decline, Congress and managers took bold, controversial steps. In 2003 a $46 million vessel‐buyback reduced the commercial trawl fleet by one‑third; by 2011 only about 108 vessels remained. That same year, the Pacific Fishery Management Council launched the groundbreaking Trawl Catch Share Program: individual fishing quotas based on historical catch and mandatory onboard observers. Within a year, discard rates plummeted from roughly 25 percent to below 5 percent.
In fact, California law explicitly prohibits bottom trawling in its state waters except under very limited conditions. Fish and Game Code § 8841 makes bottom trawling unlawful in state ocean waters unless a state commission determines that it is sustainable and low-impact. According to NOAA, commercial bottom trawling is only permitted within the California Halibut Trawl Grounds (CHTG), a small coastal zone from roughly 1 to 3 nautical miles offshore between Point Arguello and Point Mugu.
Santa Cruz Island in California’s Channel Islands (Photo: Erik Olsen)
There are gear restrictions, including bans on roller gear larger than eight inches and a requirement for bycatch reduction devices in shrimp and prawn trawl fisheries. Bycatch is nothing but pure waste, bordering on evil, and reducing it or stopping altogether should be a goal. The state also pushes more sustainable gear types and has phased out new permits for trawlers.
At the same time, an extensive system of area closures was put in place. As the documentary points out, if you protect a habitat, it can recover, and we’ve seen that in places like the Channel Islands. Since the early 2000s, Rockfish Conservation Areas and Cowcod Conservation Areas have helped protect critical habitat. Then, in 2020, new federal rules expanded essential fish habitat protections, closing nearly 90 percent of the seafloor off California, Oregon, and Washington to bottom trawling.
Fast forward: these measures have worked! By the mid‑2010s, most of the over‑90 managed groundfish stocks were recovering or rebuilt, some years ahead of earlier projections. Pacific ocean perch, for instance, had been declared rebuilt in 2017 after 17 years under rebuilding plans. The fishery earned sustainability certification from the Marine Stewardship Council in 2014. Today, only yelloweye rockfish remains overfished, with rebuilding projected by 2029.
According to John Field, who leads the Fisheries and Ecosystem Oceanography Team at NOAA’s Southwest Fisheries Science Center, this turnaround didn’t happen by accident. “The fleet, the scientists, the managers, and everyone else saw there was a serious problem, and worked together to make difficult choices and rebuild populations,” Field told California Curated. “The solution required restructuring the fishery to conserve the species, with many tough years for the fleet. Although the groundfish fishery still faces many challenges, most populations are thriving, market demand is recovering, and there is more domestic seafood on American dinner plates.”
Equipment and methods have evolved. Vessels switched from race‑to‑fish trawls to quota‑based systems, often fishing more selectively using non‑trawl fixed gear, longline, pots, hook‑and‑line for sablefish and flatfish. Electronic monitoring and observer programs help track catches closely (you gotta have enforcement).
Not all this has been smooth sailing. The shift to quotas and catch shares was controversial: many fishermen struggled with limited quotas, economic hardship, and uncertainty. Communities dependent on processors shrank as processors closed or consolidated. Some fishermen under‑caught allowable species to avoid hitting rockfish caps. Environmental groups have cautiously welcomed reopenings, but some expressed concerns that habitat recovery might still be fragile.
A ranger patrol boat off the coast of the Channel Islands in California (Photo: Erik Olsen)
So, looking back (and forward): policies over the past two decades, from trawl‐fleet reduction, gear rules, catch shares, quotas, habitat closures and strict rebuilding plans, not to mention MPAs, have turned the tide. Stocks are rebounding, many fisheries are sustainable, and management of the system is reviewed and changed if needed through amendments every two years. Of course, climate change and warming seas could render all this moot, so there’s still an element of keeping ones fingers crossed as we move forward.
This kind of drastic change takes time. And courage. And persistence. The long arc of recovery shows how science‑based regulation can bring back health to ocean ecosystems, and opportunity to coastal communities. Much of this work happens out of sight, in deep water and policy meetings alike, but its impact reaches every one of us: on our plates, in our economies, and in the resilience of the planet we all share.
I love reading New York Times obituaries, not because of any morbid fascination with death, but because they offer a window into extraordinary lives that might otherwise go unnoticed. These tributes often highlight people whose work had real impact, even if their names were never widely known. Unlike the celebrity coverage that fills so much of the media, these obituaries can be quietly riveting, full of depth, insight, and genuine accomplishment.
For two years I managed the New York Times video obituary series called Last Word. We interviewed people of high accomplishment who had made a difference in the world BEFORE they died, thus giving them a chance, at a latter age (in our case 75 was the youngest, but more often people would be in their 80s) to tell their own stories about their lives. They signed an agreement acknowledging that the interview would not be shown until after their death. Hence the series title: Last Word. Anyway, when I ran the program, I produced video obituaries for people as varied as Neil Simon, Hugh Hefner, Sandra Day O’Connor, Philip Roth, Edward Albee, and my favorite, the great Harvard biologist E.O. Wilson. Spending time and learning about their lives in their own words was a joy.
All of that is to say that obituaries often reveal the lives and accomplishments of people who have changed the world. These are stories that might never be told so thoughtfully or thoroughly anywhere else.
California Institute of Technology (Photo: Erik Olsen)
Which bring us to a quiet lab at Caltech in 1958, where two young biologists performed what some still call “the most beautiful experiment in biology”. Their names were Matthew Meselson and Franklin Stahl, and what they uncovered helped confirm the foundational model of modern genetics. With a simple centrifuge, a dash of heavy nitrogen, and a bold hypothesis, they confirmed how DNA, life’s instruction manual, copies itself. And all of it took place right here in California at one of the world’s preeminent scientific institutions: the California Institute of Technology or CalTech, in Pasadena. The state is blessed to have so many great scientific minds and institutions where people work intensely, often in obscurity, to uncover the secrets of life and the universe.
Franklin Stahl died recently at his home in Oregon, where he had spent much of his career teaching and researching genetics. The New York Times obituary offered a thoughtful account of his life and work, capturing his contributions to science with typical respect. But after reading it, I realized I still didn’t fully grasp the experiment that made him famous, the Meselson-Stahl experiment, the one he conducted with Matthew Meselson at Caltech. It was mentioned, of course, but not explained in a way that brought its brilliance to life. So I decided to dig a little deeper.
Franklin Stahl in an undated photo. (Cold Spring Harbor Laboratory Library and Archives)
The Meselson-Stahl experiment didn’t just prove a point. It told a story about how knowledge is built: carefully, creatively, and with a precision that leaves no room for doubt. It became a model for how science can answer big questions with simple, clean logic and careful experimentation. And it all happened in California.
Let’s back up: When Watson and Crick proposed their now-famous double helix structure of DNA in 1953 (with significant, poorly recognized help from Rosalind Franklin), they also suggested a theory about how it might replicate. Their idea was that DNA separates into two strands, and each strand acts as a template to build a new one. That would mean each new DNA molecule is made of one old strand and one new. It was called the semi-conservative model. But there were other theories too. One proposed that the entire double helix stayed together and served as a model for building an entirely new molecule, leaving the original untouched. Another suggested that DNA might break apart and reassemble in fragments, mixing old and new in chunks. These were all plausible ideas. But only one could be true.
Watson and Crick with their model of the DNA molecule (Photo: A Barrington Brown/Gonville & Caius College/Science Photo Library)
To find out, Meselson and Stahl grew E. coli bacteria in a medium containing heavy nitrogen (nitrogen is a key component of DNA), a stable isotope that made the DNA denser than normal. After several generations, all the bacterial DNA was fully “heavy.” Then they transferred the bacteria into a medium with normal nitrogen and let them divide. After one generation, they spun the DNA in a centrifuge that separated it by weight. If DNA copied itself conservatively, the centrifuge would show two bands: one heavy, one light. If it was semi-conservative, it would show a single band at an intermediate weight. When they performed the experiment, the result was clear. There was only one band, right between the two expected extremes. One generation later, the DNA split into two bands: one light, one intermediate. The semi-conservative model was correct.
Their results were published in Proceedings of the National Academy of Sciences in 1958 and sent shockwaves through the biological sciences.
Meselson and Stahl experiment in diagram.
To me, the experiment brought to mind the work of Gregor Mendel, an Augustinian monk who, in the mid-1800s, quietly conducted his experiments in the garden of a monastery in Brno, now part of the Czech Republic. By breeding pea plants and meticulously tracking their traits over generations, Mendel discovered the basic principles of heredity, dominant and recessive traits, segregation, and independent assortment, decades before the word “gene” even existed. Like Mendel’s experiments, the Meselson-Stahl study was striking in its simplicity and clarity. Mendel revealed the rules; Meselson and Stahl uncovered the mechanism.
There’s a fantastic video where the two men discuss the experiment that is worth watching. It was produced produced by iBiology, part of the nonprofit Science Communication Lab in Berkeley. In it Meselson remembered how the intellectual climate of CalTech at the time was one of taking bold steps, not with the idea of making a profit, but for the sheer joy of discovery: “We could do whatever we wanted,” he says. “It was very unusual for such young guys to do such an important experiment.”
California Institute of Technology (Photo: Erik Olsen)
Most people think of Caltech as a temple of physics. It’s where Einstein lectured, where the Jet Propulsion Laboratory was born (CalTech still runs it), and where the gravitational waves that rippled through spacetime were detected. But Caltech has a quieter legacy in biology. Its biologists were among the first to take on the structure and function of molecules inside cells. The institute helped shape molecular biology as a new discipline at a time when biology was still often considered a descriptive science. Long before Silicon Valley made biotech a household term, breakthroughs in genetics and neurobiology were already happening in Southern California.
The Meselson-Stahl experiment is still taught in biology classrooms (my high school age daughter knew of it) because of how perfectly it answered the question it set out to ask. It was elegant, efficient, and unmistakably clear. And it showed how a well-constructed experiment can illuminate a fundamental truth. Their discovery laid the groundwork for everything from cancer research to forensic DNA analysis to CRISPR gene editing. Any time a scientist edits a gene or maps a mutation, they are relying on that basic understanding of how DNA replicates.
In a time when science often feels far too complex, messy, or inaccessible, the Meselson-Stahl experiment is a reminder that some of the most important discoveries are also the simplest. Think Occam’s Razor. Two young scientists, some nitrogen, a centrifuge, a clever idea, and a result that changed biology forever.
At Inspiration Point, Yosemite, sticky whiteleaf manzanita tends to occupy south slopes, greenleaf manzanita tends to occupy north slopes. (Photo: NPS)
As an avid hiker in Southern California, I’ve become a deep admirer of the chaparral that carpets so many of the hills and mountains in the region. When I was younger, I didn’t think much of these plants. They seemed dry, brittle, and uninviting, and they’d often leave nasty red scrapes on your legs if you ever ventured off-trail.
But I’ve come to respect them, not only because they’ve proven to be remarkably hardy, but because when you look closer, they reveal a kind of beauty I failed to appreciate when I was younger. I’ve written here and elsewhere about a few of them: the fascinating history of the toyon (Heteromeles arbutifolia), also known as California holly, which likely inspired the name Hollywood and is now officially recognized as Los Angeles’ native city plant; the incredible durability of creosote bush, featured in a recent Green Planet episode with David Attenborough; and the laurel sumac, whose taco-shaped leaves help it survive the region’s brutal summer heat.
Manzanita branches in the high Sierra. The deep red colored bark enhanced by water. (Photo: Erik Olsen)
But there’s another plant I’ve come to admire, one that stands out not just for its resilience but for its deep red bark and often gnarled, sculptural form. It’s manzanita, sometimes called the Jewel of the Chaparral, and it might be one of the most quietly extraordinary plants in California.
If you’ve ever hiked a sun-baked ridge or wandered a chaparral trail, chances are you’ve brushed past a manzanita. With twisting, muscular limbs the color of stained terra cotta and bark so smooth it looks hand-polished, manzanita doesn’t just grow. It sculpts itself into the landscape, twisting and bending with the contours of hillsides, rocks, and other plants.
There are more than 60 species and subspecies of manzanita (Arctostaphylos), and most are found only in California. Some stand tall like small trees as much as 30 feet high; others crawl low along rocky slopes. But all of them are masters of survival. Their small, leathery leaves are coated with a waxy film to lock in moisture during the long dry seasons. They bloom in late winter with tiny pink or white bell-shaped flowers, feeding early pollinators when little else is flowering. By springtime, those flowers ripen into red fruits: the “little apples” that give the plant its name.
Manzanita flowers (Santa Barbara Botanical Garden)
One of manzanita’s more fascinating traits is how it deals with dead wood. Instead of dropping old branches, it often retains them, letting new growth seal off or grow around the dead tissue. You’ll see branches striped with gray and red, or dead limbs still anchored to the plant. It’s a survival strategy, conserving water, limiting exposure, and creating the twisted, sculptural forms that make manzanita distinctive.
And fire is key to understanding manzanita’s world. Like many California plants, many manzanita species are fire-adapted: some die in flames but leave behind seeds that only germinate after exposure to heat or smoke. Others resprout from underground burls after burning. Either way, manzanita is often one of the first plants to return to the land after a wildfire, along with laurel sumac, stabilizing the soil, feeding animals (and people), and shading the way for the next wave of regrowth.
Manzanita’s astonishing red bark The reddish color of manzanita bark is primarily due to tannins, naturally occurring compounds that also contribute to the bark’s bitter taste and deter insects and other organisms from feeding on it. (Photo: NPS)
Botanically, manzanitas are a bit of a mystery. They readily hybridize and evolve in isolation, which means there are tiny populations of hyper-local species, some found only on a single hill or canyon slope. That makes them incredibly interesting to scientists and especially vulnerable to development and climate change.
Their red bark is the result of high concentrations of tannins, bitter compounds that serve as a natural defense. Tannins are present in many plants like oaks, walnuts and grapes, and in manzanitas, they make the bark unpalatable to insects and animals and help resist bacteria, fungi, and decay. The bark often peels away in thin sheets, shedding microbes and exposing fresh layers underneath. It’s a protective skin, both chemical and physical, built for survival in the dry, fire-prone landscapes of California.
Whiteleaf manzanita leaves and berries (Photo: NPS)
The plants still have mysteries that are being uncovered. For example, a new species of manzanita was only just discovered in early 2024, growing in a rugged canyon in San Diego County. Named Arctostaphylos nipumu to honor the Nipomo Mesa where it was discovered and its indigenous heritage, it had gone unnoticed despite being located just 35 miles from the coast and not far from populated areas. The discovery, announced by botanists at UC Riverside, highlights that unique species localization, as the plants are found sometimes growing only on a single ridge or in a specific type of soil. Unfortunately, this newly identified species is already at risk due to development pressures and habitat loss. According to researchers, only about 50 individuals are known to exist in the wild, making A. nipumu one of California’s rarest native plants, and a reminder that the story of manzanita is still unfolding, even in places we think we know well.
A new species of manzanita – A. nipumu – was discovered in San Diego County last year (2024), surprising reserachers. (Photo: UCR)
For hikers, photographers, and anyone with an eye for the unusual, manzanita is a cool plant to stumble upon. I will often stop and admire a particularly striking plant. I love when its smooth bark peels back in delicate curls, looking like sunburned skin or shavings of polished cinnamon. It’s hard to walk past a manzanita without reaching out to touch that smooth, cool bark. That irresistible texture may not serve any evolutionary purpose for the plant, but it’s one more reason to wander into California’s fragrant chaparral, where more species of manzanita grow than anywhere else on Earth.
