By Heather Gordy
You’re standing on the edge of the platform on the back of the boat looking down to see your flippers hanging halfway off. You’re waiting for the moment to take that giant stride into the water. You check your equipment one last time. A splash and you’re in the water. You cross your feet at your ankles and let the air out of the buoyancy compensator. The further you sink you feel your ears tighten—the same feeling when going up in altitude along a mountain. You feel this floating sensation as if you’re weightless. You look down to spot any bigger organisms like a shark or manna ray, but you see the more simplistic life. An eel weaving its way through the water in such an effortless manor you could think of him as a seed blowing away from a dandelion. You hear the waves crashing above you and crabs clicking in a rhythmic pattern. You hear the sound of your own breathing overall and the chomping of parrot fish eating microalgae off the coral; you hold your breath for a couple seconds just to hear it. By now you have dropped down sixty feet. You think you’ve reached the bottom, but then you see the wall. A whole colonization of coral species stretch across the floor; you watch the earth drop away from you and then there’s nothing.
Pam Creech has been diving since 2006. To her, diving is something that has been an experience she shares with her family, and something that instantly connects her to a community of divers. She told me about her first night dive in Rotan, Honduras. “I came face to face with the reef and creatures opposed to seeing them twenty feet away. I remember seeing the cuttlefish flashing colors of green and red. I had no idea they could light up like that. That night, I promised myself I would be a diver for the rest of my life.”
The first time Pam saw Bonaire, a Caribbean island, she was seven years old. The last time was when she was nineteen, going five times in between. Each time she went back, she could see the reefs off the shore retracting further into the water. Development and runoff had been eating away at the reefs, and more recent escalating factors have been affecting them as well. Ocean acidification and the competition over resources have been contributing to limitations in corals growth rate.
Ocean acidification explains why the pH levels in the ocean are changing as a result of CO2 emissions in the atmosphere. With CO2 levels rising, one-third is being dissolved in the ocean decreasing the pH level and making it more acidic. With the ocean becoming more acidic this reduces the availability of certain ions, more specifically carbonate ions. Corals and other organisms use carbonate to build their exterior shells in a process called calcification. This contributes in effecting and limiting the rate at which coral can grow.
When Pam was asked how she feels to be able to see and notice this change in the time she has been diving she responded with, “It’s heartbreaking. This has been a huge part of my childhood. Whenever you go back to a place that is important to you and see that it looks different it’s hard to grabble with.”
The reefs in this area along with other areas are declining, but are also losing diversity over time. Studies are showing that different corals are responding differently to the increase in acidity. Corals are able to regulate their internal pH to a certain degree despite what the pH is in their surrounding environment. The thing that scientists are still researching and unaware of is how well they are able to continue to control their internal pH as their surrounding environment continues to change. Studies are showing that different corals have different calcification responses, and while some species are able to continue to grow at their current rate other species are declining.
Pam also said, “It scares me because if I’ve already seen so much change in just twelve years then what does that say about the future of those reefs?”
It is hard to determine the future of the reefs at this point in time because there are multiple local and global factors hindering their growth. From an evolutionary standpoint, some will win and some will lose. This is the basic concept of survival of the fittest, but it is important to recognize the factors that we are contributing to because, like ocean acidification, the effects of these processes are already happening and we can only try to reduce our effects from here.
Along with the competition between different species of coral there is also a competition for resources, mainly for space, between the algae that grows around the coral and the coral. Dr. Robert Whitehead, a professor and research analyst at the University of North Carolina of Wilmington, explained that what scientist are beginning to see is that the conditions that are causing a decrease in the rate of coral growth, as a result from ocean acidification and the decrease in carbonate, are creating conditions that algae in the area are thriving from. What begins to happen is that as the algae increases in growth they take up more space where the coral could have grown. More importantly, they take up space where coral could have dispersed their larvae.
When coral reproduces, they disperse larvae into the water and the larvae settle within hours to days. The larvae have to find a surface to attach onto in order to grow. With limited surface availability fewer larvae are surviving. Larvae growing over new surfaces are also going to be the most affected by ocean acidification because they have the least ability to regulate internal pH. This creates a competitive advantage for the algae. In areas like the Caribbean, the decrease in the amount of coral coverage has been noticeable. What this could result in are coral dominate ecosystems shifting toward algae dominate ecosystems.
Dr. Robert Whitehead said, “The changes we are seeing are unbelievable. Over the past forty to fifty years, in some areas such as the Caribbean, ecosystems that once contained about fifty percent of live coral now contain around ten to fifteen percent of live coral.”
Dr. Robert Whitehead mentioned how the coral reefs that are in the best shape are the ones not around coastal development. This is more so a result from local effects than global effects. Development and overfishing decrease the rate of coral growth more quickly and often contribute to a percentage of coral dying. There is a grazing pressure from the fishes to maintain a balance between the corals and algae by eating the algae. Overfishing has been a big concern for setting this balance off, and in some areas this has already taken effect.
In areas, such as the central pacific, people’s lives are dependent on ecotourism which is one reason for the overfishing and increase in development. With a questionable future for the reefs in these areas, and an already noticeable decline in the health of these reefs, divers like Pam and her family may lean towards looking for other reefs where they are in better shape.
What will then begin to happen is that the fishing and developmental pressures will collide with the stress of preserving the reefs. This is the major problem countries will have to deal with—the economic pressures vs. the environmental pressures. Although there are other alternatives, like constructing artificial reefs or planting ships or objects in certain areas to provide a surface for coral to attach onto and grow, we would still lose the perspective of what a natural reef used to look like. Think of what it would be like if we didn’t have the original paintings of Picasso. The images we have are beautiful, but seeing it in person and being able to see every brush stroke and layer of paint that an image doesn’t capture is breathtaking.
Global and local factors are both contributing negative effects on coral. The effects of ocean acidification, development, and the reduction of coral growth rate is happening within our lifetime. Dr. Robert Whitehead’s personal perspective on the subject is that the community needs to put more efforts toward emitting local pressures because those are things we can work on now. The global pressures are going to take more time and effort because they are already in action, but being aware of what is happening and realizing the effect of each factor involved is the first step.