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Image Credit: Brook Peterson / Coral Reef Image Bank
Most people never have and never will see a coral reef.
This is not only because most people don’t have the luxury of living near them or the capacity to travel to them, but also because we, the human race, are doing a pretty good job of destroying them.
Of course, we never set out to intentionally destroy the awe-inspiring creatures that build entire ecosystems, teeming with the most biodiverse underwater life. Yet, their demise is a byproduct of our modern lifestyle, in what scientists refer to as the Anthropocene, or the epoch in which human activity has been the biggest global influence on the Earth’s climate. Coral reefs are not the only ecosystem feeling the immense anthropogenic pressures, but they are one of the first, and are said to be the “canary in the coal mine” for climate change. This is because corals are extremely sensitive to increases in temperature, which is only one of several major consequences of climate change.
Image credit: The Ocean Agency / Coral Reef Image Bank
As the ocean warms, we are seeing a consistent increase in the summertime maximum temperatures to which corals and other marine organisms are exposed. Most corals are already living at their thermal threshold, and an increase in 1-2°C is enough to cause major physiological damage and coral starvation through a process called bleaching. The term “coral bleaching” has been popping up more frequently in the media, as it is now starting to occur annually on most tropical reefs. Many people are unfamiliar with these creatures, and grasping the concept of coral bleaching is thus challenging and seemingly irrelevant. However, coral bleaching affects hundreds of millions of people, as reefs provide food, coastal protection from storms, and economic value through tourism. As bleaching occurs more frequently and intensely than ever before, the risk of losing these ecosystems is much higher. In fact, it’s already happening.
Born and raised in the Arizona desert, I myself had no conception of what lived in the ocean until I was old enough to travel to California and explore the little worlds of life in the tide pools. I’d get sucked into these tide pools containing sea anemones, urchins, and hermit crabs, with little indication that anything in them could harm me. Little did I know, we were doing more harm to these marine creatures than they ever could or would do to us.
When I was 14, I decided I wanted to become a marine biologist. Through a series of fortunate events and tons of support from my family, I learned how to SCUBA dive, got a degree in marine science, and now continue to study the fascinating marine world in some of the most colorful reefs I have ever seen: the Red Sea and the Great Barrier Reef. I have always treasured my opportunities to explore these worlds, but now I realize I have been taking the health and abundance of coral reefs for granted. The more I learn about how our modern lifestyle - dominated by consumption of disposable goods, processed food, dirty energy sources, and our mindset that nature is meant to be conquered - is killing the very things I love, I feel compelled to be a translator for these ecosystems. As hope dwindles for these ecosystems to exist in the future for our kids and grandkids to enjoy and rely on, I work to become an advocate for awareness and change, because they do have their own voice, but many chose not to listen or understand.
To speak for the ocean and coral reefs in particular, I must first share the facts about them and one of their largest current threats: coral bleaching.
Illustrations by Melissa Pappas
Corals are animals similar to jellyfish, as they are in the same family, Cnidaria. Corals, like jellyfish, use their stinging cells (called nematocysts) to capture live prey in the surrounding water column, which makes them heterotrophic feeders. Importantly, corals have a symbiotic relationship with microscopic single-celled algae called zooxanthellae that live within the coral’s outer skin-like endodermis that can harvest energy from sunlight through photosynthesis. These algae, although tiny and short-lived, have provided corals with the ability to survive and thrive in nutrient-poor environments like tropical waters where they can still gain food through photosynthesis. The relationship between corals and these algae has existed for millions of years and allows the coral animal to create impressive structures and entire ecosystems on which the marine world relies.
Illustration by Melissa Pappas
Unfortunately, the stability of this coral-algal relationship is being threatened as disturbances in the environment such as poor water quality, changes in pH and salinity, and increases in water temperature disrupt the communication between coral and algae. When the relationship between coral and algae is no longer mutually beneficial, the algae vacate the coral. Because the coral relies on the algae to provide it with up to 99% of its food source through photosynthetically-produced sugars, the loss of the algae leads to coral starvation. Although corals can gather organic matter from the water column, there isn’t much available on the reef. When zooxanthellae leave the coral, the remaining tissue and skeleton appear white because the algae give the coral its characteristic color. Thus, the phenomenon of algae vacating its coral host is termed coral bleaching.
Once bleached, a coral does not die immediately. However, it is compromised, as it is not receiving nearly enough carbon (food) to sustain itself. Bleached corals are more susceptible to disease, just like we are more susceptible to sickness if we are starving. Once bleached, corals do not have much time to recover before they die. It is in this critical stage where water temperatures need to return to normal to allow corals to take up their algae from the water column or repopulate their cells with remnant algae in their tissues.
Corals have an amazing capacity to recover from environmental disturbances, but if these disturbances interrupt the recovery process, the condition becomes chronic and full recovery is no longer possible. To put things into perspective for coral recovery from bleaching, coral colonies have been found to recover their algal population in less than a year (spanning from 5 to 10 months), but entire reefs require decades to recover from bleaching. By 2050, mass bleaching events are predicted to occur every year on most reefs, and on some reefs, including the Great Barrier Reef, this annual cycle is predicted to start by 2020 (this year!). We have already started to see these predictions come true, as shown by a major bleaching event on the Great Barrier Reef in February 2020. Effects of climate change are staring us in the face and if we hope to save these ecosystems, we have to act now.
What you can do
Illustration by Melissa Pappas
Eat less meat – A major cause for deforestation is to make space for cow grazing. The loss of trees causes a loss of carbon sequestration (storage), which in turn allows more carbon to be emitted into the atmosphere, leading to increased global temperatures.
Be aware of what you consume (food and otherwise) – Disposable goods require energy to produce. Buy quality over quantity, if possible.
Use less energy at home – this includes water and driving.
Spend more time outdoors – Mental and physical health increase the more we spend time outdoors, decreasing our need to rely on manmade objects to nurture our souls.
Vote – Take ownership in choosing the voices you want to direct our countries.
Grow or hunt your own food – Food waste is a huge problem, and changing our relationship with food can change how we consume it. Sustainability and eating healthy can make a big difference in helping the planet.
Learn about natural spaces – and how to help keep them natural.
Teach others - Encourage small changes in as many people as you can, the world needs many imperfect eco warriors over a few perfect ones
-Melissa
