The Algae behind the Glowing Waves
By Anya Stajner
Back in March of 2020, I was blown away by all the beautiful imagery I saw on social media of a bioluminescent algal bloom in Southern California. Pictures and Instagram stories of the beach at night where the crashing waves were lit by a neon glow filled my feed. Being that I’m from the Bay Area and sheltering-in-place I didn’t get to view this bioluminescent bloom myself, but if you’ve ever seen one, you’ll know what I mean when I say they’re magnificent.
The first time I saw a bioluminescent algal bloom was when I was a marine science student doing a study and research program at Bodega Marine Lab through my college UC Davis. Friends showed up at my dorm late at night spontaneously asking me to join them in some night swimming since there had been word of a bioluminescent bloom coming up. I excitedly switched into my swimsuit and loaded up some friends in my car, and with the top down, drove up the coast to a local beach hoping we’d get to witness the bioluminescence. We met up with another car of students and we all squeezed our cold bodies into borrowed wetsuits and ran towards the water. When the ocean was in view, rather than being stopped in my tracks, I was drawn in even more powerfully towards the water. Before me crashed waves not lost in the darkness like you would expect on a cold night, but instead glowing: lit up by what looked like could only be magic. As our group went straight into the frigid water, hanging onto each other to keep grounded against the tide, each time a wave crashed against me, it appeared as if my body was the night sky. Teeny tiny twinkling plankton plastered against the deep black of my wetsuit gave the appearance of constellations. Looking at the bioluminescence on me and around me is an experience that inspired so many feelings within me namely appreciation, excitement, and curiosity about the ocean. As a marine science student I knew a lot about this seemingly ethereal phenomenon; and although it wasn’t on my mind in those magical moments, I knew that they’re not always as beautiful as I had experienced.
As many of you living in the San Diego area may know right now, this recent and sensationalized bioluminescent bloom which started in late march of 2020 has very quickly gone STANKY. This recent bloom to bust happened because the species of algae that lit up the coast, Lingulodinium polyedra, or L. poly produces a noxious smell as it dies. L. poly produces both bioluminescence and a terrible odor, but what else can bioluminescent algae do?
The residents of Southern California may have had to plug their noses near the coast for a few weeks, but compared to other algal blooms around the world, SoCal got off easy. In other places around the world, this same oceanic event has caused massive disarray. But first, let’s cover the science behind these magical scenes.
Just to be clear, the waves that were glowing in Southern California in March and April of 2020 -- and all other glowing waves I’d have to assume -- are in fact not materialized by magic. But don’t worry, I’d say the science is even cooler. This type of glowy phenomenon is known as bioluminescence. Bioluminescence is the emission of light as a product of a chemical reaction happening inside a live plant or animal. I know that that might sound crazy, but I’m betting that you already know of an animal that’s bioluminescent: a firefly! A firefly is a great example of a bioluminescent animal you may have encountered on land, but in the ocean, bioluminescence is a very diversified trait meaning that many different types of plants and animals can do it. In the case of the neon blue waves during a bioluminescent bloom, the culprit causing the light display is usually a population of dinoflagellates. Dinoflagellates are single-celled organisms in the plankton, which means that they are super tiny and mostly in surface waters. And while not all dinoflagellates are bioluminescent, practically all coastal bioluminescence can be attributed to them.
As I mentioned earlier, the blooms seen this spring were mostly made up of the dinoflagellate species L. poly. So while all the instagram influences flocked to the coast to document the glowing waves for their stories, what they were really documenting was the combination of the chemical luciferin with the enzyme luciferase and marveling at the energy released as light as luciferin loses an electron. If this chemical light show wasn’t happening in such densely packed tides -- 20 million dinoflagellates per liter of ocean water to be exact-- instagram influencers and other beach spectators wouldn’t even see it because each individual reaction only emits light for .1 second; which makes the reaction happen faster than the blink of an eye which actually takes 4 times as long!!!!! And no, dinoflagellates do not do this purely for the enjoyment of humans as you might've been wondering. This chemical reaction is actually meant to startle predators to slow down their feeding rate, and in the process it also acts as a secondary alert system to attract the predator of whatever is trying to eat the dinoflagellate. The dinoflagellate has evolved to emit this bioluminescent response when it is stressed, like when it is being handled by a predator, but this also results in a glowy light display when waves crash, which can definitely be quantified as a stressful situation if you are only the size of a single cell. Oh and these bioluminescent events are referred to as blooms because of the density of the dinoflagellate population. Like I said, the total number of dinoflagellates can get up to 20 million per liter of water, and happens when ocean currents pull deep sea nutrients to the top of the water column and algal populations --like the dinoflagellates -- bloom as a result. Algal blooms are sometimes referred to as red tides, because during the day time the densely packed bloom can make the ocean appear a reddish brown color. And while not all algal blooms are made up primarily of bioluminescent dinoflagellates, I would say that the bioluminescent blooms are the most charming. So yeah, bioluminescent blooms are pretty cool, and are pretty much a result of stressed out dinoflagellates flexing their coolest chemical reaction.
However, the universal truth is that beauty fades. The ephemeral nature of bioluminescent algal blooms may be part of the draw, but this spectacular sight left behind a foul odor that crept further inland than the local acai bowl shops. So why did this happen? Algal blooms are a very important oceanic process and are often the primary source of energy for a very productive food web. But not every algal bloom is the same and that is because there are many different types of dinoflagellates that have the potential to bloom during these events. The reason the San diego beaches got stinky following the bioluminescence was that the species of dinoflagellate making up the algal bloom, L. poly in this case, releases a noxious gas when the organism dies and breaks down leaving a smelly reminder of how powerful the ocean is. That being said, San Diego’s stinky algal bloom, while maybe was not the most lovely to inhale, was not detrimental as far as some algal blooms go. In addition to a trail of bioluminescence and ocean productivity, some algal blooms leave a trail of death earning them the brand of harmful algal blooms.
The difference between the type of algal bloom that happened in San Diego that offered a beautiful display of light versus a harmful algal bloom, is the species of dinoflagellate that grows. The dinoflagellates that “bloomed” in San Diego were a stinky, but safe species, alas there are other species of dinoflagellates that when they grow out of control have harmful effects on fish, shellfish, marine mammals, birds, AND humans. Some of the human illnesses that harmful algal blooms cause can be completely debilitating. So not only are some algal blooms bioluminescence free, but they’re also dangerous!
The generally picturesque west coast of Florida and the rest of the Gulf of Mexico start to expect a harmful algal bloom every August when oceanographic conditions become favorable. Some of the factors that contribute to a bloom include the temperature of the water, the salinity, the light saturation, the water chemistry, and the currents. There are a lot of moving parts to create such a perfect storm. But when they do happen, these harmful algal blooms can wreak major havoc across the coast producing terrible smells, toxifying our food supply, and killing marine life. The species behind the harmful algal blooms in the gulf of Mexico is known as Karenia brevis. K brevis is a small but mighty dinoflagellate that produces a potent brevetoxin: a type of neurotoxin that compromises an animal's nervous system. During the months that K. Bevis blooms, dead fish and marine mammals litter the beach and harmful toxins linger in the air posing the risk of human respiratory illnesses. In 2018, which had particularly a strong bloom, the Florida Fish and Wildlife Conservation Commission reported 288 manatees dead from the red tide. Sea turtles and dolphins are also victims of harmful algal blooms and will wash up on shore dead as well turning these usually picturesque beaches into a morgue. Moreover, the reaches of K. brevis extends beyond the beach as the shellfish that accumulate the harmful brevetoxin get harvested by commercial fisheries and toxify our food supply. These toxic shellfish can cause neurotoxic shellfish poisoning, amnesic shellfish poisoning which can literally give you chronic amnesia, diarrhetic shellfish poisoning enough said, and paralytic shellfish poisoning which can paralyze you for the first 12 hours of being affected. Luckily for you all I’m quite faint of heart so I won't be listing off the rest symptoms, but trust me these conditions are as terrible as their names suggest. Even on the more moderate side, swimming in a harmful algal bloom can irritate your skin and even just taking a run on the beach and exposing yourself to the air can put you at risk of exacerbated asthma, bronchitis, or pneumonia. Not only can harmful algal blooms cause physical harm to humans and marine life alike it can also harm local and regional economies. Harmful algal blooms can force the closure of scallop and other shellfish fisheries costing local economies tens of millions of dollars each year. For all of these reasons marine scientists have been actively trying to understand the workings of a harmful algal bloom.
While algal blooms are in general very important to ocean ecosystems, harmful algal blooms stand to do a lot of damage, which is why scientists are concerned with an increasing trend of harmful algal blooms in many areas like florida and the gulf of mexico. As we discussed, there are a lot of moving parts that contribute to an algal bloom and even more so for a harmful algal bloom. One factor that has played a large hand in increasing the chances of a harmful algal bloom is agricultural runoff. Agricultural runoff is extremely nutrient rich and gets into the ocean by traveling through streams and rivers. Once the nutrients -- nitrogen and phosphorus in particular -- arrive at sea, they feed the K. brevis which can then outcompete the other species of algae. Additionally harmful algal blooms tend to thrive in warm waters, leading some scientists to conclude that climate change might also be playing a role in the increased intensity of harmful blooms that many scientists have noted. Because what exactly is causing an increase in harmful algal blooms, and if there even has been an increase at all, is still a somewhat controversial field (then again what isn’t these days), marine scientists remain working hard to monitor harmful algal bloom events in the hopes of further understanding any changes in bloom trends and to provide communities with precise forecasts. The National Oceanic and Atmospheric Administration (aka NOAA) is a great resource that offers reliable harmful algal bloom forecasts, which are important to helping keep the Gulf of Mexico locals informed on the up to date conditions of harmful algal blooms so that they can plan and prepare accordingly.
If you’re hoping to vacation in Florida (after the COVID pandemic is over of course) and you don’t want the water to be red and beaches dead, you might be wondering if scientists have figured out a way to combat the harmful types of algal blooms. For now, scientists have been pursuing two main strategies. The first and definitely more high maintenance course of action is pumping infected waters into 25,000 gallon tanks where they can be treated with ozone and pumped back into the ocean, purified. This process is supposed to mimic the purification of aquariums and pools, but for now it’s still in its early testing phases. The other option that is being explored is to introduce diatoms, another species of algae, to compete with the toxic K. Brevis, but for now, this potential solution is also still being tested. Because there are no safe solutions yet, harmful algal blooms will continue to reign terror on marine ecosystems and beach goers alike, but on the bright side this gives marine scientists ample opportunity to learn even more about how red tides work and how to deal with agricultural runoff in a way that prevents it from exacerbating harmful blooms.
As it does with many other things, instagram only showed us the beautiful side of algal blooms. When it seemed like everyone was sharing spectacular footage of the glowing waves there was actually a dark underbelly to all the fuss, well I guess in San Diego’s case a stinky one. Yes, bioluminescent blooms are beautiful and deserve to be appreciated, and no they’re not all harmful, but it seems unfair to talk about the beautiful and not mention the rest. Today we learned that the majestic light show brightening the night sea earlier this year was the product of dense populations of dinoflagellates performing a chemical reaction which resulted in bioluminescence. We learned that this was one type of algal bloom that happens when nutrients are brought to the top of the water column. In the case of San Diego, that nutrient input came from deep water, whereas in the Gulf of Mexico we learned that an input of agricultural runoff can exacerbate a type of algal bloom that is toxic to people and marine life. These harmful algal blooms, sometimes referred to as red tides due to the reddish tinge the dense populations of dinoflagellates give the water, can kill marine life like fish, manatees, and dolphins as well as cause neurological damage to humans who might accidentally ingest toxic shellfish. Lastly we touched on the science of forecasting harmful algal blooms and potential solutions for future blooms. Just like the beach just offers a peek into the wonders beneath the ocean, the hype over the bioluminescent waves was just a small piece of the algal bloom puzzle. Seeing everyone’s photos on facebook and instagram reminded me of my own experience with a bioluminescent bloom and made me eager to get below the surface and ponder the more complex picture of algal blooms as a whole. The ocean is an expansive and exciting body of water that can give us striking memories but can also strike down on the health and economy of entire coastlines, and algal blooms exemplify that quite beautifully.
Connect more with Anya on Twitter @ScienceStajner or on Spotify and Apple Podcasts by streaming her new podcast “Wet”.
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