Coral is colorful, beautiful, and very delicate. It is also a very important part of the planet's life support system, and even though we humans don't think about it often as a general rule, we depend on healthy coral reefs for our own survival. You probably know that a coral reef is made up of countless tiny individual animals called coral polyps, and that coral is easily damaged. There are some other threats to coral besides careless snorkelers and scuba divers; some of the top threats include invasive species like Crown of Thorns Starfish, pollution, and coral bleaching. Here, we'll take a look at the link between coral bleaching and pollution.
What is Coral Bleaching?
Coral polyps feed primarily on zooplankton; however, microscopic algae called zooxanthellae which live inside their tissues also provide them with nourishment. As much as 90% of coral's nutrition comes from these tiny plants, which lend corals part of their color.
Corals rely heavily on this symbiotic relationship. When it breaks down, coral bleaching results. Coral bleaching is a term that describes the loss of color that occurs when a stress response within the coral polyps cause them to expel the zooxanthellae they rely on. When this happens, the coral's skeletal system is revealed, leaving the corals looking white, or in some cases, resulting in pale pastel shades of blue, yellow, or pink.
The primary cause of coral bleaching is increased sea temperature. When water temperatures increase by even one to two degrees Celsius, bleaching can occur. Even though the corals remain alive for a short while after bleaching strikes, they quickly starve. Left without their primary source of nutrition, they are also more susceptible to predation and to diseases that leave lesions on the coral which can be compared to open sores or wounds on the human body.
The Pollution Problem
Just as your body can heal itself from small injuries quickly given the proper circumstances, coral can survive a bleaching incident, so long as water temperatures return to normal fairly quickly, or so long as other stressors are removed. Unfortunately, those other stressors tend to be caused by human activity, and when they are combined with bleaching, they prevent coral from healing itself and they make those lesions worse - kind of like what would happen if you were to pour an irritant onto a cut on your hand or expose the cut to bacteria instead of keeping it clean. Stressors that contribute to and worsen coral bleaching include oil spills and pollution; other contributing factors to coral die off and bleaching, including increased sedimentation, low oxygen, and changes in salinity, are affected by human activity and are sometimes the result of humanity's interference with the ecosystem via land-based pollution.
Much of the pollution that ends up in our oceans is the result of soil and other pollutants that wash into waterways that ultimately lead to the sea. Herbicides and pesticides used on lawns, gardens, and in agricultural applications contribute to the problem, and so do chemical fertilizers. Some things individuals can do to help reduce that load include turning to organic solutions for maintaining lawns and gardens, xeriscaping rather than attempting to grow lush green lawns, and buying responsibly raised organic foods whenever possible - not to mention reducing reliance on fossil fuels.
Coral tissue damage is normal to a certain extent; but by contributing to pollution or supporting businesses that release industrial chemicals into the environment, we make the problem worse. At SDTN, we're committed to promoting reef health, and we hope you will join us in our efforts to prevent the current bleaching epidemic from worsening. Besides making ecologically responsible choices and reporting invasive species sightings whenever possible, we as a diving community can help educate others about the importance of coral reefs and ways everyone can help improve coral's odds of survival while contributing to a cleaner, healthier planet for all of us.
Comments
This makes me so sad.