When color bleeds to white - Bleaching coral reefs

I'm moving, tousled, weightless, my hair streaming in front of my eyes as I try desperately to stabilize myself by lightly swishing my hands, keeping my legs completely still. Hand flapping is a movement that comes naturally to me; I've seen the home videos from childhood of an excited bald child waving her hands around in a flurry of activity. This time, however, I'm not simply excited. I'm also kind of wary, because I'm staring at a fiery red branch of coral, and the ocean waves are pushing me ever closer and closer to this bizarre animal that, if I touch it, will burn like fire for the rest of the day. I would kick my legs, but I would crush the unassuming coral beneath me. I'll find out later while I was dodging the infamous fire coral that one of my friends, enamored with a feather duster worm, ended up waving her hand inches from the nose of a nurse shark she didn't even see hiding beneath the reef. Nurse sharks aren't aggressive, but it just goes to show there is always more going on in a reef than you know.
When I think back on my days swimming in Belize, I am constantly pulled between wonder and anxiety. It's anxiety for how close I came to slamming into the delicate animals I was trying to observe, anxiety over the number of dead corals I saw, pale white brain corals wedged between red fire corals or more demure greens, and especially anxiety over the future. While through my eyes seeing the reef for the first time was magical, all I had to do was glance at my professor's faces when they didn't know I was looking, their eyes turned down, and hear them whisper, "It's changed." The reef was not doing as well as in past years. It was evident to anyone who had already been there or had eyes keen enough to see the coral skeletons left over, covered in algae, that the reef was not thriving as it once had. I resolved then that I would one day seek out what had evaded me: a magnificent specimen of coral reefs. I would see the Great Barrier Reef. Little did I know that within a year, the Great Barrier Reef would experience one of its most severe bleaching events in history, followed by another that is underway as I write this. While the Great Barrier Reef is by far the most famous reef, its death throws heard around the world and described in a number of influential news sources, the Great Barrier Reef does not perish alone.

One of my favorite fish at the New England Aquarium. The mandarinfish lives in the living coral exhibit where it can frequently takes cover in the crevices as curious visitors search for this painted beauty.

There are a number of problems facing coral reefs today, including vibrio (a bacteria that causes disease), sedimentation, crown-of-thorns starfish, and even an overgrowth of algae, but what we see at work in the Great Barrier reef and in other areas is perhaps one of the most dramatic threats. In order to understand coral bleaching, you must first understand the structure of coral. There is an old-timey question old jokester uncle figures say, which goes, when presented with something new, "Is it an animal, vegetable, or mineral?" In the unique case of hard corals, the answer is all three. Coral is a small animal, shaped rather like a sea anemone. It's outside is fleshy and soft, vulnerable, but for the fact that it has the incredible ability of building a limestone protective skeleton around its delicate frame. When you look at a branch of coral, you are actually looking at something rather like an apartment building that many corals have built, each small porous hole in the limestone structure a separate apartment for each tiny organism. Once established, however, these organisms cannot stray far. They can open up and reach tiny finger-like structures outside of their limestone castles, searching for food particles that float close enough to fall into their grasp. This, however, does not satiate hungry corals. In addition, corals line their fleshy translucent tissues with cells of algae. As the algae are exposed to sunlight, they photosynthesize and make food for the hungry corals, providing most of the energy that the corals need. Without these algal helpers, corals eventually die. I first learned the name of these vital little algae in the aquarium, gaining countless hours of amusement watching children stumble over the name as I talked to them about coral in the kids corner. They are called zooxanthellae (zoo-zan-thel-ee).

The healthy colors of a coral reef, with butterflyfish

It is the seemingly irrational, self-mutilating action of expunging zooxanthellae that characterizes coral bleaching. Scientists, after countless hours of studying bleaching corals, know what causes bleaching, but have yet to explain what practical purpose the corals' banishing of the algae may serve. What is evident is that corals bleach when they get stressed. Corals, despite being covered in stone, are very delicate. They require just the right amount of sunlight, very particular temperatures, and clean water. When it gets too warm or too cold, or the sunlight is too direct, or there is pollution, the corals get stressed, becoming a fluorescent color, a warning of what is to come. Soon after, the coral spits the algae out of its body. Since the algae is what gives coral its color, the coral is left a ghostly, skeletal white, as if it has been doused in bleach. After expelling the algae, coral have a short time to take up new algae, but if the coral remains stressed, it will simply die, the only thing left the white limestone structure it built for protection. Reefs are sometimes capable of surviving bleaching events; A coral reef may be able to bounce back from a bleaching event after about a decade given the right conditions. If bleaching occurs too frequently, however, corals cannot regenerate. This is why, with two years of bleaching in a row, scientists are in mourning and obituaries for the Great Barrier Reef have been circling the internet.

A bleached coral in front, with healthy non-bleached corals behind

When a coral dies, it does not die alone. A coral reef is a thriving community. While the coral provides the structure, a number of animals build their homes out of what the coral has provided. Sea urchins graze on the algae that grows in the limestone, small fish hide in the crevices of coral to escape predators, some sharks swim around the outside of the reefs, other sharks hide beneath coral crevices, giant hermit crab scavenge along the sea floor, and sea anemones attach themselves to old coral skeletons while anemonefish start families in their tentacles. When a reef dies, it is the underwater equivalent of the death of a city. In short, it is a natural tragedy.
As the climate warms and weather patterns become more extreme, we have seen more coral bleaching, and pristine reefs are few and far between. While it is tempting to lament the destruction of one of the greatest natural wonders of the world, I'm not ready to give up on a future where immersing yourself in an ocean brings you to underwater communities you could hardly imagine. There are a number of things that we can do in this moment:

• Climate change and warming are linked to carbon emissions. Do what you can to limit yours. If it's safe, ride your bike. Take public transportation. Carpool. Buy a fuel efficient car. Eat a few meatless meals. Limiting how much meat you eat has a significant impact on your carbon emissions.
• Be careful what you put on your lawn. While you may live miles and miles from the coast, water running off from your lawn will mix with other water, underground or in rivers, and this water has a tendency to find its way to the ocean. Chemical fertilizers and pesticides are notorious for throwing the ocean out of balance, sometimes by causing large blooms of algae, other times by simply increasing pollution.
• Spread the word about what is happening to the coral reefs. If you are lucky enough to get the opportunity, volunteer at a local aquarium or environmental organization. If you can, invest in organizations that are dedicated to protecting the reefs and investigating ways that we can help them survive.
• If you get to travel someplace where you can see coral, make sure you are following local guidelines to keep coral safe. Kicking coral, stirring up bottom sediment with your flippers, and even wearing certain kinds of sunscreen, when multiplied over many tourists, can stress coral. Make sure that the hotels and restaurants you go to are making sustainable choices by reducing their pollution impacts and offering sustainable seafood.
• Look at your elected officials' history of protecting environment and climate. Hold them accountable for the laws they support and the impact we are having on Earth. What we do in America doesn't just impact our country. The carbon emissions we have released have contributed to the warming that is killing the Great Barrier Reef. Understand that inaction in arresting climate change is the same as complicity in the destruction of one of the most beautiful and diverse ecosystems on the planet.

All hope is not lost. There are some resilient reefs that have shown less damage than other reefs. We know because of history that organisms are capable of adapting to a changing planet if given time. Meanwhile, all we can do as we attempt to reduce our carbon emissions is to limit the other stresses we put on reefs, like pollution and overfishing, in order to give them time to adjust. I, for one, hope that in the future, I will be able to once again submerge my face in sea water and see before me not the skeletons of once great underwater kingdoms, but a brilliant swirl of reds, yellows, and greens as nurse sharks lie like carpets under the tapestries of coral and curious fish swim to my goggles to stare at their own reflections, blissfully unaware of the fate they escaped.

Carbon Dioxide

*Before you read this blog article, please pay special attention to the links I've added. Some of them are graphics which I do not have the rights to that will add greatly to your understanding of this concept.

I've been a bit stuck for the past couple of weeks. While my fingers go numb from the cold pulling in water samples on a windy bay and my mind begins to spaz as I do the mental somersaults of calculating radiocarbon, my heart sinks to the pit of my stomach every time I see another article about decreasing scientific funding, about Scott Pruitt's latest opinion on carbon dioxide, and as school teachers receive books in the mail riddled with erroneous information on "why scientists are divided on climate change." After I finish my water samples, I go to class and I learn about plummeting oxygen in the ocean. I read articles about the Great Barrier Reef dying. I am bombarded by threats to the EPA and NOAA. Every day, the folds of the internet and the current political climate take turns both whispering and shouting. Is it the fate of this group of hard working passionate people to be ignored? Is all of our understanding of the planet to be thrown away because we don't like the picture we are seeing?

An incredibly warm day in February on the Narragansett Bay

In the past few weeks, I've wanted to talk about many ocean problems. I wanted to talk about the reefs around the world that are dying at alarming rates. I wanted to talk about how there is less oxygen in the ocean than before, which is bad for species that rely on oxygen. I wanted to talk about how the ocean is getting more acidic, and this hurts species that have hard shells, like shellfish. I wanted to talk about sea star wasting syndrome, a terrible disease that is linked to warm ocean temperatures. There is one thing all of these issues have in common: carbon dioxide. Carbon dioxide is natural and necessary, but it is also linked to a huge number of the ocean's problems. In order to fully understand it, we have to go to the source.
So let's start with how carbon dioxide fits into nature. In a previous blog article, I talked about how plants and phytoplankton take up carbon dioxide in order to go through photosynthesis, releasing oxygen. When we breathe out, we do the reverse reaction, called respiration, and we exhale carbon dioxide. This carbon dioxide that we exhale is the reason people with panic attacks will breath in and out of a paper bag; it forces you to breath in the carbon dioxide you already exhaled (this is all related to the level of acidity in your body. I won't get into it, but you can learn more about it here).

Photosynthesis

Breathing, however, isn't the only way that humans release carbon dioxide. When we burn coal, petroleum, or natural gas (considered to be the cleanest of the three options), carbon dioxide is released into the air. Natural levels of carbon dioxide in the atmosphere help to keep the planet warm enough for life by working as an insulator of the sun's energy. This is because energy from the sun, like all energy, travels in waves. You see this in action every day as you observe different colors, which is a result of different wavelengths of light (this is the distance between two peaks in the waves). The energy of the sun enters through the carbon dioxide in the Earth's atmosphere at a particular wavelength that can easily pass through the gas. After the energy hits the surface of the Earth, it is reflected back at the atmosphere, but because some of the energy has been lost, it travels at a different wavelength which is not as good at getting through a layer of carbon dioxide. This means some of the sun's energy is reflected back to stay on Earth. The more carbon dioxide there is, the more energy gets reflected back, and the warmer the earth gets. If this all seems rather abstract, think of carbon dioxide as a blanket, keeping Earth nice and warm. The thicker the blanket, the more heat gets trapped.

Scientists have had some inkling that humans may be impacting the climate since about 1890, but it's become more clear as data supporting this idea has continued to build. There is scientific consensus that the Earth is warming, and according to NASA, the most likely cause of climate change is human's release of carbon dioxide. In addition, a recently published open access paper by John Cook and his colleagues found that 97% of scientists agree that the most likely cause of climate change is human activity (if you are interested in investigating for yourself, you can find the paper here). Just take a look: this model from Bloomberg took NASA's data on a number of factors that scientists have speculated cause climate change and compared their levels to global temperatures. Greenhouse gases, which include carbon dioxide, were the closest match by far.
Earth's climate has changed before. There used to be grape vines in Canada, for example, when the vikings showed up. Before humans started releasing massive amounts of carbon dioxide, the earth was actually cooling. However, temperature change on a global scale, without man's assistance, does not happen at the rate it is currently happening. Have we been measuring global temperatures since the times of King Tut? No. However, we can figure calculate past temperatures because of the hard work of countless dedicated scientists who have looked at ice cores, or long tubular samples of ice from the Arctic. When looking at the stump of a tree, you can count the rings of a tree to know its age and you can look at the distance between the rings to tell how much it has rained. In a similar way, scientists have developed ways to estimate the temperature of the planet from layers of ice, as well as extracting samples of the gases that were trapped in the ice at the time it froze. All of this has led to the conclusion that the earth is warming at a rate which has not been seen before. A brilliant artist, xkcd, who frequently does science related pieces, put together a brilliant timeline of Earth's global temperature for reference, and I highly recommend you check it out.
So the Earth is warming, and there are more greenhouse gases than before. This is a global problem, not just us. Why should you care? The US has a disproportionate impact on carbon emissions. Based on 2011 measurements, while China releases the most carbon in total, the US releases the most carbon per capita, meaning the average US citizen releases more carbon than anyone else from any country in the world. This is is large part due to our very comfortable, tech heavy lifestyles. We also tend to rely on our own personalized modes of transportation as opposed to public transportation, and most of us have diets with a lot of meat and get exotic foods shipped from far away. Scientists frequently refer to the amount of carbon we release as individuals as our carbon footprints, and as Americans, ours are massive. However, there are many ways that we can try to lower our carbon footprint and therefore be better neighbors, such as carpooling, taking faster showers, turning the heat in your house down a couple of degrees, buying more fuel efficient cars, or even eating less meat (being vegetarian is one of the easiest ways to lower your carbon footprint dramatically).
In the coming weeks, I will be touching on the many ways that carbon dioxide has an impact on the ocean, but for now, what I want you to remember is:

1. Carbon dioxide is a natural and essential gas on planet Earth.
2. Human emissions of carbon dioxide from burning coal, petroleum, and natural gas are the largest on record this year, and the US contributes a disproportionate amount.
3. Greenhouse gases, including carbon dioxide, are believed to be the leading cause of climate change on Earth. While climate change has happened before, it has not occurred at this rate.
4. Carbon dioxide has a huge impact on the oceans, not only as they warm, but in a number of ways that I will discuss later.

This blog article has been a bit ocean light, but that's only because I want to get into ocean specifics in more detail, and in order to do that, it is important to understand where these ocean problems are coming from. The scientific community has been warning about the dangers of rising carbon emissions for years. If by some trick of destiny the thousands of them who have come to this conclusion turn out to be wrong, limiting carbon emissions will only keep the earth cleaner and will help with other problems like ocean acidification (more on that later). However, if the scientific community, a group of people who have nothing to gain from sounding the alarm, is right, and we turn our backs on this now, we will create a problem that will have sweeping ramifications, on land and sea.