StressPart 2 in The Nature Conservancy Series
by Kemit-Amon Lewis and Lisa Terry
The Nature Conservancy Caribbean Program

I stress, you stress, we all stress! And it’s not just us. In fact, 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 to sustain their symbiotic relationship with zooxanthellae–a microscopic, photosynthetic, dinoflagellate algae.
Corals and zooxanthellae share a symbiotic relationship in that zooxanthellae live in the tissue of corals. In return, zooxanthellae provide food to corals. They also give corals a colored appearance, which is based on the pigment of the zooxanthellae. You may think of it as a landlord (coral) – tenant (zooxanthellae) relationship. Under normal conditions, this symbiotic relationship works well for both the coral and the zooxanthellae but when stressed, corals evict their zooxanthellae tenants to conserve energy. With the white calcium carbonate skeleton that the corals grow exposed, through the colorless coral tissue, coral colonies appear white or “bleached”.
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 but, 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 may weaken corals so much that they become more susceptible to coral diseases.
Some natural and man-made stressors that impact coral reefs include storms and high wave events, land-based sources of pollution, in-water discharge of waste and sewage, removal of herbivorous fishes, destructive fishing practices, ocean acidification, and invasive species. The most massive and widespread stressor in recent years has been climate change and its associated impacts.
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.
Since the 1980s, The Nature Conservancy has worked with partner organizations to implement coral conservation programs throughout the Caribbean with the goal to eliminate or reduce man-made stressors that harm Caribbean coral reefs. By doing so, we can build resilience – making reefs stronger against the impacts that we cannot easily control, like mass bleaching events.
StressWhether it is our coral reef restoration work, our support for Marine Protected Areas, our BleachWatch VI community-monitoring program, or the Reef Responsible Sustainable Seafood Initiative, TNC is committed to creating “hope” for reefs–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.
Do you snorkel, swim or dive around reefs in St. Croix? Then you can help monitor the extent and severity of bleaching events when they occur. Become a BleachWatch Virgin Islands volunteer and report what you see on the reef using or the BleachWatch VI mobile app. The BleachWatch VI program that prepares for, monitors, and responds to bleaching events. Come to an in-person training, or take the training online.
There will be a BleachWatch VI training open to the public in St. Croix on August 22, 2017 from 5:30pm-6:30pm @ The Nature Conservancy, 3052 Estate Little Princess; contact Lisa Terry at for more information.
The Nature Conservancy

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