Coral Bleaching

There is confident certainty in all climate-related data that environmental conditions are changing, and changing fast. Global temperatures are higher on average than ever before, atmospheric CO2 concentrations have now surpassed 410ppm – marking the highest concentrations in all of Earth’s history – and continue to rise at an increasingly faster rate, worrying all climate scientists for the potential ramifications of an increasing trend. Increased CO2, among other greenhouse gas species (methane, nitrous oxide, carbon monoxide, and many more) serve as a blanket in the atmosphere, trapping in heat that is reflected from Earth’s surface, ultimately warming the planet. Increased temperatures are reflected throughout the ocean, as sea surface temperatures are evidently increasing with the most drastic changes observed at the tropics (equator) and in the polar systems. Warming waters and increasing atmospheric CO2 concentrations together wreak havoc on marine reef systems. Coral is a living animal, with a hard skeleton made up of calcium carbonate, the same compound that composes chalk.

Fun fact: chalk is actually made up of dead coccolithophores, small phytoplankton that live in the ocean that are made of hard calcium carbonate shells!

 

As more CO2 is added into the atmosphere, more CO2 is introduced into the ocean. The imbalance of equilibrium leads to an increase in the dissolution of calcium carbonate into its constituent ions of calcium and carbonate, and we observe a process termed decalcification.

Corals are literally dissolving before our eyes all around the globe, evident through more fragile reefs, slower growth rates, and overall degradation. Increased ocean temperatures are responsible for what is termed ‘coral bleaching’, a phenomenon observed in reefs where the microorganisms that inhabit the coral skeleton, zooxanthaele, die or leave the structure because they cannot tolerate the warming conditions.

Corals that have undergone this process become ‘bleached’ and often have white spots or are completely white in structure, where only a bare skeleton remains and life is gone. Corals are the fundamental component to any reef system, and as coral conditions continue to decline, reef species and diversity are diminishing as a result.

While diving is a wonderful way to observe these beautiful reef systems first-handedly, it is important to recognize the changes that reef systems worldwide are experiencing. From my own experience, I have witnessed the decline in the Florida Keys reef system through a tremendous increase in bleached coral among the same reefs I have dove for the past 4 years. I’ll say it once more; conditions are changing, and changing fast. A number of non-profits, charities, organizations, businesses, and educational groups continue to advocate the preservation of reefs worldwide, and it all stems from public awareness.