Harbor porpoises as seen from the Golden Gate Bridge. (Photo: William Keener/Golden Gate Cetacean Research)

Harbor porpoises haven't been seen in San Francisco Bay for more than 60 years. But now, they're coming back through the Golden Gate in growing numbers and researchers are trying to understand why they’re returning.

The best place to look for them is 220 feet above the water on the pedestrian walkway across the Golden Gate Bridge. That's where Bill Keener of Golden Gate Cetacean Research photographs them, holding a massive telephoto lens over the side of the railing.

"There's a porpoise right there, coming very, very close," he says pointing. A dark shape appears in the water. It's a harbor porpoise, coming up for air. "And here's a mother and calf coming straight at us."

The porpoises have dark gray backs and pale bellies. They're about five feet long, smaller than most of their dolphin relatives.

"Look at that! That one's on its side," Keener says. "The porpoise turned on its side. It's spinning and it's feeding."

Porpoises spin as they go after schools of herring and anchovies, which means these porpoises are feeding in the middle of a heavily-trafficked shipping lane. "The porpoises have found a way to not only avoid the ships, but it's also the noise they make," says Keener.

Studying a Shy Marine Mammal

Seeing this behavior is huge for Keener. Harbor porpoises are notoriously shy in the open ocean, so they're tough for researchers to study. Here in the bay, Keener and his colleagues have identified 250 individual porpoises with their photos by looking for unique scars and color patterns on the animals.

Porpoise mating display as seen from the bridge. (Photo: William Keener/Golden Gate Cetacean Research)

When these researchers first started their work on the bridge, they caused a bit of a stir. "You noticed there was a Golden Gate Bridge patrol officer here just a few minutes ago," says Keener. "Well, we're staring down at the water for hours. They'd start getting worried about us. But they know us now. They know what we're doing."

Of course, the big question is why harbor porpoises disappeared in the first place. Keener says the bay has historically been porpoise habitat. Their bones have been found from hundreds of years ago.

"And then there were reports in the 1930s. And then we don't really have reports from around World War II. And there were a lot of things going on during World War II that could have caused that."

San Francisco Bay became a wartime port and a major ship-building center. The Navy strung a seven-mile-long net underwater across the opening of the bay to keep out Japanese submarines. Hundreds of mines were planted in the waters outside the Golden Gate.

Keener says all that activity certainly would have disturbed the porpoises. But there's a bigger change that may have driven them away.

The Changing Bay

To see it, we head toward the Golden Gate Bridge on a twenty-two foot boat with Jonathan Stern, a whale researcher at San Francisco State University. Stern was the first person to spot the porpoises in the bay three years ago.

"I just couldn't figure out what they were doing here. It's like when you see somebody you're used to seeing at work and you see them somewhere, in Hawaii or something. What are you doing here? You're out of place," says Stern.

The bay we're gliding over today is a far cry from the bay in the 1950s and 60s. As the Bay Area boomed, so did water pollution. Keener says raw sewage used to flow right into the bay. "I remember coming across the Bay Bridge when I was very young and it would just smell. It would stink."

After the Clean Water Act was passed in 1972, the bay's water quality began to improve. But Stern says it took time for the food web to come back. "It takes the biology a while to track the chemistry. So it's not surprising that it's taken years for this ecosystem to generate like this."

Stern says it's also possible that the porpoises had to rediscover the bay. "Because over 60 years, we're talking about a number of generations of porpoises. So it's quite likely that San Francisco Bay as a location, as a habitat was out of the institutional memory of the harbor porpoises off the coast here."

Bill Keener and Jonathan Stern search for porpoises in the bay.

As we slow down under the bridge's span, Keener keeps an eye out. "There are porpoises between us and the south tower at 200 yards," he says.

Keener and Stern have a special permit that allows them to approach the porpoises. We wait, listening for them to surface.

"I just heard one here. Here's a cow-calf pair close to the boat and we'll hear this puff," Keener says.

We hear two loud puffs as the porpoises surface just off the bow. "The old time sailors used to call them puffing pigs. That's the exhalation," says Keener.

The harbor porpoises seem calm around boats in the bay, which Stern says will let researchers study their life cycle and social structure, as well as how they might react to big events like the upcoming America's Cup race. Overall, he says it's a good sign that the porpoises are here.

"It's one of those very few good news environmental stories. And it's in our backyard. You know, there was the will to get the bay cleaner and we're now starting to see the effects of that. It gives one hope."

I’m always amazed at how many San Franciscans are aboard and who have never been on the waters of the Sanctuary, much less out to the islands.  The trips start with some trepidation about the weather, the wind and waves and the 27-mile transit to the islands.  The nervousness fades as we immediately see several small harbor porpoises before we even cross beneath the Golden Gate. There are more of these shy cetaceans than I have ever seen, and local researcher Bill Keener of Golden Gate Cetacean Research confirms that the small dolphins have returned to the San Francisco Bay after an absence of approximately 65 years.  Their recent foraging in the bay may be an indicator of the health of the ecosystem.

Clearing Point Bonita, we enter the shipping channel and begin our search for whales, but it is the pelagic seabirds that first greet us.  We are currently experiencing a changing of the guard in the transition between seasons. The productive ecosystem off the coast of California has three oceanographic seasons: upwelling season in the spring and early summer; relaxation in the late summer and fall; the storm season in winter.

During the upwelling season (March-July), strong northwest winds and the south flowing California current combine with the earth's rotation to drive surface waters away from the shore. These surface waters are replaced by an upwelling of nutrient-rich deeper water from offshore. The nutrients become available for surface dwelling phytoplankton (microscopic marine algae). Phytoplankton form the foundation of this oceanic food web and the combination of nutrients and increased sunlight in spring initiates a bloom of life that radiates up the food web from small shrimp called krill to the great whales. An abundance of phytoplankton, zooplankton, and young fish are food for animals at higher levels of the marine food web. During the summer months endangered blue, humpback and other species of whales visit our National Marine Sanctuaries of Monterey, the Gulf of the Farallones and the Cordell Bank to feed on this abundance of krill. Here's a video from a summer trip.

Now, the season is in the relaxation mode, and the calm seas and sunny skies help relax the passengers as we watch pelagic and double-crested cormorants, arctic terns and marbled murrelets wing past. The islands are in sight, but no whales so far.  With less food, the humpback whales are making their exit as the California gray whales enter our waters in their annual migration from the feeding grounds near Alaska to the warm lagoons of Baja California Mexico where they calve. The gray whale is a success story.  Hunted to extinction in the Atlantic, and with a few hundred individuals in the eastern Pacific, protections afforded under the Marine Mammal Protection Act has allowed this population to increase to well over 20,000.

Mid-channel, we are alerted by another vessel, The Salty Lady, that they are onto humpback whales.  Captain Jimmy turns back towards the mainland and we see four humpback whales slowly swimming south.  After a half hour, we head back to the islands and soon sea a California gray whale engaging in what looks like feeding near the south side of the Island. Nearby are two shark-watching boats and I wonder if the divers inside the cage witness the whale.

Out near the continental shelf, we are joined by over one hundred Pacific white-sided dolphins and among them northern right whale dolphins.  The large pod of dolphins swim alongside us, surfing the bow wave as they head north past Middle Rock and north Farallon Islands towards Point Reyes and the Cordell Bank.

Just as the great whales migrate, so too do the great white sharks which visit the islands during this season to feed.  As we discuss sharks on our way back to San Francisco, I reflect that like the whales. We can protect them in our sanctuary, but we can't protect them as they transit the open sea in their great migrations.

Like the whales, sharks need protection locally and internationally and require shark sanctuaries, protection from fisheries on the high seas and at home, and shark finning banned worldwide.  Perhaps one of the most important things we can do is to protect sharks that are reproducing and to protect nurseries like the southern California bight for white sharks and the San Francisco Bay for sevengill sharks, soupfin sharks and the smaller hound sharks that pup there.  Through our  Shark Steward program with The Turtle Island Restoration Network, we are now developing a San Francisco Shark Sanctuary to protect local sharks reproducing in the bay so that sharks will continue to swim the waters of California.

The first time I visited Guadalupe Island-aka The Island of the great white shark-was under sail in the early nineteen eighties. A rugged and desert island one hundred fifty miles off the coast of Baja California, the island itself was then only inhabited by goats and a fish camp. The deepwater anchorage provided little shelter from the swell and above water the island felt remote and spooky. But beneath the surface I experienced a rich marine ecosystem from abalone to giant kelp to Guadalupe Fur Seals. During that voyage we didn’t experience a white shark, but on a recent last trip aboard a Mexican ecotourism boat we experienced five in one dive. Like the Farrallon Islands off San Francisco, Guadalupe is as an aggregation site for white sharks.

Last week I joined four Italian photographers, three Japanese and six Americans on a Mexican Shark watching vessel to enter cages and experience what it is like to be in the water with a great white shark.

All trained SCUBA divers, I was surprised at how little my fellow passengers- all educated and experienced divers- knew about sharks, threats to sharks and shark conservation. During our five days aboard I was able to raise awareness via video and shorts talks peppered by the real action in the water. Seeing a white shark swim is like nothing else and the sharks made a clear impression on us all.

We can look at the statistics. For example, millions of sharks are killed each year for their fins. Countless millions of others harks are killed as bycatch in longline fishery. As many as ninety percent of some pelagic sharks are now missing from the ocean, and one third of these are on the IUCN Red List and threatened with extinction. Great white sharks are one of the few species internationally protected with trade restrictions, yet white shark fins are coveted and the Pacific population hovers around 1000 individuals.

Yet sharks get a bad rap. My colleague at the California Academy of Sciences, Dr. John McCosker points out that in the last one hundred years, there have been round 100 white shark attacks in our State waters, with a 10% fatality. The odds of getting killed (if you even enter the water) are greater by simply crossing the street.

How many people actually ever get to see a white shark?

Statistics pale when watching a white shark swim. You are left with the feeling that these sharks belong and we are the interlopers. Unless we reconsider our views on sharks, white sharks could easily go extinct in our lifetimes. But tourists like these might hold the hope. Click, click, the shutters fire as sharks swim past an arm’s reach. Click click fire the synapses as the mind wonders at the size and power of this amazingly adapted beast.

Risks

Interacting with wildlife, especially top predators can be thrilling, but can it also be dangerous.
Wildlife tourism has been long established in the terrestrial environment, but not without problems. Animals and tourists have been killed through negligence and greed. Eventually, guidelines have been established in many regions to protect both the tourists and the wildlife such as tigers and elephants from harm. Many have strict rules like the tours lead through SEEtheWILD. Profits raised through the tourism are directed towards enforcement or conservation but just as important, local jobs are created. Some of these jobs go to the very people who once harvested or poached the animals after protective laws were established. In Baja, Grey Whale Expeditions lead by the American Cetacean Society or events lead by local naturalists of the Ocean Conservation Society allow people an enjoyable first hand experience and provides a valuable economic influx to areas without other options outside of fishing.
Last year I accompanied a sea turtle operation lead through SEE Turtles tagging and tracking sea turtles in Baja. The tourists benefit from hands on experience and learn about the ecology of the animals.

The guides benefit by employment. The turtle populations benefit by more eyes and hearts looking out for their population. Scientists benefit through more data provided by the citizen scientists.

More Valuable Alive the Dead

Like the terrestrial analogue, shark watching operations have experienced a few glitches along the way. These include an over saturation of operations in South Africa leading to overuse of chum and feed impacting the local ecology, altering the shark’s behavior, impacts of sharks with cages and boats and allegations of increased shark attacks. Some non-cage operations in the Bahamas have lead to the accidental death of photographers by Tiger sharks. This has lead to serious restrictions/elimination of chumming and shark/object interactions. However, through government and self regulation my experience at the Farallones and Guadalupe Island is that operators are cleaning up their acts and working for shark conservation. Increasingly via first- hand experience people are observing the beauty and power of sharks, and understanding their importance through shark and shark cage diving. Today, white shark watching occurs off the Farallon Islands under permit by the Gulf of the Farallones National Marine Sanctuary requiring trained naturalists and using strict best watching practices. Many countries like Palau and the Bahamas are banning not only shark finning, but all shark fishing and are benefiting form shark tourism. Sharks are worth more alive than dead. A recent study on the economics of shark tourism suggests one reef shark may bring up to two million dollars in its lifetime through tourism.
On my recent trip to Guadalupe Island, the crew was entirely Mexican and their families helped with activities like provisioning and the vessel preparation. We also helped a local shark scientist Mauricio Hoyos who is engaged in research on the island, and the cage operators contribute to his non profit Tiburon Blanco. Our international team of divers were as amazed by the beauty of the sharks as they were incredulous of the travesty sharks are experiencing worldwide. Each walked away with increased respect both for the majesty of the shark and also for the need to protect them. In our home waters, white sharks are returning to the Sanctuary after migrating thousands of miles and tourists are starting to head west to visit them. We call it Sharktober and all month Sea Stewards and partners will be celebrating sharks and all wildlife. More on learning about and celebrating the shark can be found at Sea Stewards.

Let sharks live.

Surfers do more than surf. The Surfrider Foundation, originally formed to protect a surf beach and beach access, has developed into an international organization involved in multiple programs ranging from wildlife protection to ocean policy. As a surfer and a long term member of the foundation, I have been involved in countless beach clean-ups. We routinely walk the beaches pulling plastic bags, bottles and cigarette butts. Over the years, we have picked up tons of trash. Some of the beach clean-ups are organized, and sometimes I just pick up trash before or after surfing. This Saturday, September 17, Surfrider will join thousands of Californians for the California Coastal Cleanup Day.

As awareness increases, we are seeing fewer large pieces, but we still find countless cigarette butts, bottle caps and water bottles. We need to do more than just clean up, we need to stop it at the source. Our foundation has developed a plastics campaign called, "Rise Above Plastics." We must stop the plastics before it hits the beach. It is easily done. A metal water bottle, reusable shopping bag and an ash tray would significantly reduce plastics in the environment.

Here's the "Rise Above Plastics Pledge":

There is a section of the Pacific Ocean twice the size of the continental United States called the Great Pacific Garbage Patch. Within it, 100 million tons of plastic swirl in a vortex of currents. There is so much plastic in the water that it outnumbers zooplankton by six to one!

This plastic ends up in the stomachs of marine birds and animals. In fact, one million seabirds and 100,000 marine mammals die globally each year due to ingestion of or entanglement in plastics.

Plastic is forever, with virtually every piece of petroleum-based plastic ever made still in existence. That's why it's so critical to our oceans and beaches that we dramatically reduce our use of plastics, especially single-use plastics, starting today.

You can make a difference for our world's oceans, waves and beaches — pledge to rise above plastics today.

I commit to do my part to rise above plastics and protect the world's oceans, waves and beaches from plastic pollution. I will do this by:

- Using reusable bottles for my water and other drinks. By using just one reusable bottle, I will keep 167 single-use plastic bottles from entering the environment.

- Using cloth bags for groceries and other purchases. For each reusable bag I use, I will save approximately 400 plastics from being used.

- Recycling the plastic bags and bottles I already have. For every thirteen plastic bags I don't use, I will save enough petroleum to drive a car one mile.

This season, we wanted to expand that idea to include films and videos on similar topics. The thinking is, we here on QUEST are never at a loss for story topics about science here in the Bay Area. There must be a bunch of other media makers telling these kinds of stories so let's get some different perspectives from the community.

Stanford marine biologist, Stephen Palumbi

QUEST folks have long been fans of the video work that Dan Griffin/ GG Films has been doing with Stanford marine biologist, Stephen Palumbi. Together they create "Microdocs" which they define as "short attention span science video." Their videos are usually 2-3 minutes long and feature one specific aspect of marine ecosystem sustainability. Microdocs topics focus largely on coral reef health, sustainability and diversity- subjects that have required them to travel to such remote tropical locations as American Samoa, The Bahamas, Fiji and Micronesia. Ahh, the price that we pay for our art…

Purple sea urchin in beaker

"Ocean Babies on Acid" focuses on an experiment that Stephen Palumbi and UC Davis marine biologist Eric Sanford are doing to study the effects of ocean acidification on sea urchin larvae off the California and Oregon coasts. One of their goals is to find out if the increased acidity caused in part by increased CO2 levels in the atmosphere makes it difficult for marine species to grow their shells. The study is unique in that they're not only studying the external aspects of these creatures but also delving into how ocean acidification may effect the animals on a genetic level.

You can watch the full-length video on the Microdocs site here:
Ocean Babies on Acid

Work from the Algalita Marine Research Foundation indicates there is six times more plastic than phytoplankton (single-celled marine algae) per weight and fifty times more plastic than zooplankton (small crustaceans and larvae) in the North Pacific Gyre. Over half this plastic is plankton size: less than 60 mm or a quarter-inch in size. These tiny plants and animals are the base of the ocean food web, and animals consuming plankton from herring to whales are ingesting plastic.

Plastics are Forever

The plastic doesn’t go away, it just gets smaller. Approximately 70% of plastic sinks to the bottom where it sits like a time bomb waiting to be assimilated. The larger pieces float along until cast ashore or ingested by a marine animal. Plastics absorb organic pollutants like toxic sponges, concentrating the poisons and finding their way into the food chain from fish to humans. One study found fulmars, ocean-going birds that visit our waters, have over 30 pieces of plastic in their stomachs. A sea turtle found dead off Hawaii had over 1000 pieces of plastics in its intestines. Hundreds of thousands of seabirds, sea turtles and marine mammals die from plastic ingestion each year. Americans generate 10.5 million tons of plastic waste a year but recycle only 1 or 2% of it. An estimated 14 billion pounds of trash – most of it plastic – is dumped in the world's oceans every year. Plastic bags and other plastic garbage thrown into the ocean kill as many as 1 million sea creatures every year.

This problem occurs in every ocean in the world. We are killing our wildlife and poisoning ourselves through a preventable problem. For hundreds of miles of ocean, patches of plastic cross our bow. A sailboat is like a small planet: we have limited food and water and we generate waste. On past Sea Stewards expeditions, we are careful to keep all plastic aboard, and minimize plastic wrapping and bags in our provisioning. No plastic goes into the ocean on our watch.

Make a Change, Clean it Up

We can reduce our waste using less, bringing your own bag to the grocer and using a metal water bottle.
Join us and hundreds of thousands of Californians on September 17, California Coastal Clean Up Day. You can participate at one of the regular clean ups organized by your local Surfrider Foundation or start your own. Plastics reduction and marine debris clean up is part of Sea Stewards Healthy Oceans Initiative.

Watch Plastic in the Pacific to learn more about the Great Pacific Garbage Patch.

The team of international scientists published a grave assessment of current threats and a stark conclusion about future risks to marine and human life. If the current trajectory of damage continues, the world's ocean is at high risk of entering an unprecedented phase of extinction of marine species.
The greatest threat the group concluded was climate change leading to ocean acidification.

Ocean acidification is a direct result of the absorption of carbon dioxide by the ocean. This threatens all marine animals and plants that secrete calcium carbonate as part of their structure. Ocean acidification can prevent marine animals, from snails to plankton to corals, from building their protective shells.

Historically and before the presence of humans, three factors have been present in every mass extinction event: low oxygen levels (hypoxia) and the absence of oxygen (anoxia) causing ocean dead zones; ocean warming; and acean acidification. Thanks to modern technology, we have accelerated and exacerbated the conditions leading to the historical marine extinctions. Already one quarter of the world’s coral reefs have vanished and another one third are endangered. Ninety percent of many some of the ocean’s great fish have vanished. Species like sharks contribute to the health of the ocean yet are being systematically and unsustainably fished.

These climate and marine experts found strong evidence that the effects of the three factors, coupled with other human induced impacts such as overfishing and nutrient runoff from farming have already caused a dramatic decline in ocean health.

The last great extinction event occurred 55 million years ago, where over half of all deep sea species became extinct. It has been determined that the rate of carbon absorption in the ocean is already greater than the conditions leading to that event.

It was concluded that these impacts are synergistic and the rate of degeneration is far faster than previously predicted. The report urges strong and rapid action by governments to reduce carbon emissions such as those urged by the last IPCC report, better manage our fisheries – especially those of the high seas, and increase marine reserves to serve as pockets of resilience.

The conclusions are serious indeed yet it also offers solutions, many of which we can deal with in our daily lives. As citizens, we can work for ocean health by driving less, eating only sustainable seafoods, minimizing run off from detergents and fertilizers and supporting marine protection.

The ocean and ocean life are too important to lose through negligence or ignorance.
As one of the co-authors of the event Dr. Dan Laffoley stated, “The time to protect the blue heart of our planet is now, today and urgent.”

The ocean is our planet’s heartbeat, and the future heartbeat for billions of humans. Lets keep it beating.

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San Francisco's Pier 39 is home to only a few sea lions this summer.

I spent Saturday sightseeing in San Francisco with a friend visiting from out of town, and I thought I’d check in on the sea lions at Pier 39. Just a few years ago, there were about 1600 of them, slithering on and off the wooden docks, basking in the sun, and barking at one another. Then in 2009, most of them swam away, as QUEST blogger Amy Gotliffe explained. The sea lions’ favorite food, herring, was in short supply, so they went to Oregon to feast on anchovies and salmon. Now the herring are making a comeback—will the sea lions return too?

This weekend the floating wooden palates at Pier 39 were mostly bare; there were perhaps a dozen sea lions. We would expect the sea lion numbers to be low this time of year, herring or no herring. In the summer, sea lions travel down south (the Channel Islands, San Diego, Baja) to breed. But there were still fewer sea lions at Pier 39 than in summers past.

Sea lions will eat a lot of different prey items: octopus, squid, small sharks. But their bread and butter is herring, which have been hard to find in recent years. The herring fishery is the only fishery still in operation in San Francisco Bay, and it closed during the 2009/2010 season (December through April), because there were so few fish. This year, the herring fishery opened again, but with a lower quota than in the past, to allow the fish to recover.

There are a few hypotheses about why the herring numbers dipped so low in 2009. First, herring lay their eggs in the brackish waters of the estuaries around San Francisco Bay. Each female fish can lay up to 50,000 eggs, which are a prized commodity in Japan. However, the years leading up to 2009 were drought years, so the estuaries were saltier than usual. That may have affected the herrings’ spawning success. Second, the 2007 Cosco Busan oil spill may have affected herring health. Researchers found oil-soaked embryos, which were deformed. Third, herring declines may be the result of climate change. As surface waters get warmer, there is less mixing with cold, nutrient-rich water from the bottom of the ocean. There are also big patches of the ocean that have very little oxygen. These hypoxic zones are deadly to their inhabitants, and are affecting many marine species.

However, the herring appear to be making a comeback, possibly because the past few years have been wet and the estuaries are sufficiently fresh, or because the spilled oil has been flushed from the Bay. Time will tell whether the sea lions follow their food and return to Pier 39. I hope they come back—along with the twists and turns of Lombard Street and the Golden Gate Bridge, the Embarcadero’s sea lions are one of my favorite San Francisco treasures to show off to visiting friends.

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Forty years later the rivers are cleaner, millions of acres have been established as national parks and wilderness areas and over all the air quality has improved. But what about the other 71%? Over half our oxygen comes from the ocean. Fish feed millions and the beauty and complexity of marine life leave us in awe. Yet today, a year after the ravages in the Gulf from the BP Oil spill, 90% of large pelagic shark species are going extinct from overfishing and for their fins. Whales and seals have been hunted to a genetic bottle neck and are hunted still. The wolves of the sea, the bluefin tuna, are being fished to the vanishing point. While a thousand other insults are being inflicted on Mother Ocean, where is our outrage?

New oil wells are being considered along our coast while nuclear power plants hum along our shorelines vulnerable to Tsunami and earthquakes. Recent die-offs of sardines in southern California; emaciated and sickly sea lions along the coast, vanishing salmon and stranded leopard sharks in the San Francisco Bay are bellwethers reminding us that the ocean is sick.

The ocean needs our help.

After a week of celebrating the Earth, it's time to celebrate our ocean with World Oceans Day. This day had been unofficially celebrated every June 8 since its original proposal in 1992 by Canada at the Earth Summit in Rio de Janeiro, Brazil. It was officially recognized by the United Nations in 2008. Since then, WOD has been coordinated internationally by The Ocean Project and the World Ocean Network with greater success and global participation each year. World Oceans Day is an opportunity every year to honor the world's ocean, to celebrate the all marine life.

It's time to motivate change and let our leaders know that marine life and ecosystem are worth protecting, and they need our protection now. This summer, celebrate World Oceans Day and tell our representatives we need a sea change. With our partners from The Ocean Project, Sea Stewards will be coordinating a World Ocean Day Celebration at Crissy Field in San Francisco on June 11. We will be celebrating all marine life, especially sharks, and motivate people to protect the ocean and ocean life we love.

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Sometimes, the wind and the waves whip the ocean into a lather. And that word—lather—is a pretty accurate description of sea foam. Sea foam is made of dissolved organic matter, a substance that is so important in the world ocean that it gets its own acronym, DOM. DOM consists primarily of the broken-down bodies of phytoplankton, including microalgae and bacteria. Algal blooms, when they start to die off, create lots of DOM. In sea foam, the DOM acts like soap, creating small bubbles that float on the water.

Dissolved organic matter is full of proteins and lipids (plus lots of carbon, which we’ll get to later). The DOM molecules can act as surfactants, similar to soap and other detergents. The molecules have a hydrophilic end that sticks to water and repels oil, and a hydrophobic end that sticks to oil and repels water. The DOM decreases water’s surface tension and promotes the creation of bubbles as the water is stirred by wind and waves.

Big storms can create huge amounts of sea foam. In 2007, the area north of Sydney, Australia was dubbed the Cappuccino Coast, as foam engulfed 30 miles of shoreline. All this foam can obscure things like rocks and sea snakes, so foam frolickers should frolic with caution.

The best part about sea foam, in my opinion, is not these big foam events, but the fact that sea foam calls attention to dissolved organic matter. We rarely see it (it is dissolved, after all), and we rarely think about it, but DOM plays a massively important role on Earth. It is a key part of the marine food web, though it is hard to eat, because the particles are so tiny. Bacteria are some of the few organisms can eat DOM.

Also, the DOM in the ocean is one of Earth’s largest carbon reservoirs. DOM is produced in the upper ocean, where the phytoplankton and zooplankton live—DOM is made of the spilled contents of their bodies and their cells. The DOM that is not consumed at the surface gradually drifts downward in the water column; it can be found in the deepest parts of the ocean, albeit at lower concentrations than at the surface. As we continue to pump carbon dioxide into the air, some of this carbon ends up as DOM, and it travels slowly throughout the ocean. Next time you see sea foam, think of the dissolved particles of organic matter and the important role they play in the ocean.

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