The Great Coral Bleach

kemit-amon-lewis-at-tnc3Kemit-Amon Lewis earned his bachelor’s and master’s degrees in marine sciences at Savannah State. Now he is the Caribbean Coral Conservation manager for The Nature Conservancy. With massive coral bleaching events taking place around the world, we asked him a few questions about what it means for the oceans and what he’s doing to combat it.

What exactly is coral bleaching?

All living organisms stress, from the largest whale to the smallest plankton. In the case of corals, small marine animals, stress can cause severe impacts including death, increased cases of diseases and the inability of corals to sustain their symbiotic relationship with zooxanthellae—a microscopic, photosynthetic dinoflagellate plankton (Try to say that three times fast).

Corals and zooxanthellae share a symbiotic relationship. Zooxanthellae live in the tissue of corals. In return, zooxanthellae provide food to corals in the form of carbohydrates; they also give corals a colored appearance. Think of it as a landlord (coral) – tenant (zooxanthellae) relationship. When stressed, corals evict their zooxanthellae tenants in an effort to conserve energy. Now the white calcium carbonate skeleton is visible through the colorless coral tissue and they appear white or “bleached.”

bleached-coral-south-china-sea-c-kemit-amon-lewis-copy
Bleached coral in the South China Sea (courtesy of Kemit-Amon Lewis)

Why is it bad?

Coral bleaching typically occurs during extremely warm water events and is the result of a combination of elevated sea surface temperatures and light intensity. If conditions return to normal within a few short weeks, corals may recover. However, if the sea surface temperature stays above normal for extended periods of time, the corals may die. In some instances, even if corals recover, the stress from the bleaching event weakens corals so much that they become more susceptible to other diseases.

What are the side effects for the ocean overall?

Corals are often referred to as the rainforests of the sea. They are high in biodiversity and are important for ecological, economic and cultural benefits provided to many tropical states and island nations. When they die, habitat for fish, coastal protection from storm surge, a large section of the recreational SCUBA diving industry, sandy beaches, medicinal breakthroughs and cultural practices all erode away with them.

How can the average person help?

Reduce or eliminate human impact. The most massive and widespread stressor in recent years has been climate change and its associated impacts. However, there are a number of site-specific natural and man-made stressors that impact coral reefs including storms and high wave events, land-based sources of pollution, in-water discharge of waste and sewage, destructive fishing practices, ocean acidification and the introduction of invasive species.

For reefs to survive, we must continue the serious global conversations about climate change and be innovative in our approach to reduce our dependence on fossil fuels and the over-production of greenhouse gasses. We must also continue to protect and restore critical coral reef sites on national and local scales. Get involved. Consider this an open invitation to visit my home island of St. Croix and volunteer with one of the many conservation projects I work on.

staghorn-at-cane-bay-nursery7
This staghorn coral nursery propagates healthy coral for transplant. (courtesy of Kemit-Amon Lewis)

What are some of the efforts you employ as the Caribbean Coral Conservation manager to protect coral?

Since the 1980s, The Nature Conservancy has worked with partner organizations to implement coral conservation and restoration programs throughout the Caribbean. The goal of these initiatives is to eliminate or reduce man-made stressors that harm Caribbean coral reefs, while actively growing important reefbuilding species.

Through research and conservation, we can enhance resilience – making reefs stronger against the impacts that we cannot easily control, like mass bleaching events. It is my hope that coral reefs and the many ecological, economic and cultural benefits that they provide to Caribbean Islanders, and visitors, will continue to exist now and into the future.

I don’t see an alternative to our coral conservation work in the Caribbean. The Caribbean without reefs is not a place that I want to imagine and definitely don’t want to witness.

Advertisements