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Threats to Corals

Cruise Ships

Cozumel is one of the world's largest cruise ship ports. Up to 7 ships visit each day, bringing over 3.6 million passengers to the island each year. While these tourists have become vital to the economy, this industry is the largest threat to the Cozumel coral reef ecosystem.


Cruise ships spread coral-killing diseases through their ballast, across the Caribbean. Their giant propellers disturb marine life, resulting in steep decline population declines beneath their routes, and stir up sediment, which after settling on the corals block their photosynthesis, starving them to death.

Cruise ship threats

But even more devastating is the resulting human development catering to this industry. MSC Cruises and the local Yucatan peninsula oligarchic Molina family, have lobbied to build a fourth Pier; located both along the edge of the UNESCO protected Marine Park and right beside the CCRRP. This proposed $25 million 800-yard long pier, would have capacity for another 11 cruise ships bringing another 40,000 tourists to Cozumel every day. What’s left of our shallow reefs will be destroyed by the construction of the pier, and of up to 50 new beach clubs along the island’s coast.

Villa Blanca Reef that we have spent 7 years restoring would be destroyed. Everything that the CCRRP has and is trying to accomplish will be negated – unless the construction is stopped.

To prevent this, we have joined a collective with other Cozumel ecological organizations, dive shops and concerned citizens, fighting this megaproject in the Mexican courts. We succeeded in gaining a temporary injunction against construction, as the project failed to obtain proper permits and did not properly consult Cozumeleños on how their environmental rights would be affected! But with MSC Cruises and the Molina family appealing the ruling, our fight will continue until permanent a suspension is achieved.

You can help in 4 ways:

1. Do not visit Cozumel by cruise ship.
2. If visiting from the mainland, do not take Winjet Ferry. It is owned by the Molina family.
3. Use your voice to help us gain international media attention!
4. D
onate to our Legal Defense Fund.


Lack Of Water Treatment

Coral thrives in water with low nitrate levels, where very little algae can block the sunlight it needs for photosynthesis.


This is one of the reasons the water around coral reefs is so clear! When untreated sewage, which is high in nitrates, is dumped in the water by cruise ships or overflows from septic tanks, it upsets the ecosystem’s natural balance and causes algae blooms. These massive blooms can outgrow coral colonies at an alarming rate, covering a year’s worth of coral growth in a day, and starving the coral of the sunlight it needs to survive. 


We have to clean our coral garden daily to keep some algaes from overgrowing and smothering our corals.

Coral bleaching
Diving classes and conservation

New developments plan to dump wastewater directly onto Palancar reef, one of the most beautiful and diverse diving locations in the world - and they’re not the only ones - at least a dozen major hotels on Cozumel have been caught dumping untreated water directly into the ocean.

To counteract this, we will continue to monitor water chemistry around the reefs. We are also identifying which corals have best adapted to higher nitrate water so we can grow more resilient colonies, and continuing our advocate for more stringent water treatment regulations.

Cozumel’s wastewater disposal laws have not been updated in 25 years, and dumping untreated waste in the marine park is, unfortunately, legal.


There’s only one water treatment plant on Cozumel, and it only services the northern portion of the island. 

Diver in Mexico

Human Damage

What can an individual do to

prevent damage?

There are small things we can all do to prevent further damage to the reef while visiting Cozumel.


Don’t wear sunscreen. Sunscreens, deodorants, and other beauty products contain non-biodegradable compounds that block UV light. It protects your skin, but if it washes into the ocean it attaches to corals, blocks the UV light they need for photosynthesis, and can kill them. Even products that are marketed as “reef friendly” still contain compounds that can be harmful.

Rashguards or UV protection shirts are a common solution in hot climates. These thin and quick drying shirts protect us from the sun without killing corals. They are readily available all over the island – buying one in Cozumel also helps the local economy.

Educate yourself on safe diving practices. While divers are often the some of the biggest supporters of conservation efforts, few of us are trained to be reef safe. New divers need to stay a safe distance from corals until they have mastered their buoyancy, so as not to hit or kick delicate corals.

Our Coral garden is set up near dive shops where new divers are trained, so we spend a lot of our time rescuing coral that has been kicked and broken by inexperienced divers. Many experienced divers know a lot about fish, but very little about the coral reefs that protect them.  

Learning to properly interact and protect coral allows you to enjoy diving with the knowledge that you are not harming the beautiful environment you came to Cozumel to explore. You can find information on our courses here:

planting coral
PADI Research Diver


Diseases threaten corals like every other organism.

coral diseases

When a coral polyp is sick, it expels its symbiotic algae – the organism that allows it to photosynthesize – and loses its brilliant color. This is called coral bleaching. If the corals recover quickly, they can get their algae back and survive. But if conditions are too stressful for too long, the corals die.


Bleached, or “dead” portions of reefs are becoming more common as human activities, algae blooms, rising water temperatures, and pollution increasingly stress the corals immune systems, making them significantly more susceptible to disease.

There are two major diseases threatening Cozumel’s coral right now: Stony Coral Tissue Loss Disease, which manifests as rapidly expanding lesions on coral colonies, and White Band Disease, in which tissue peels off from colonies leaving behind a “white band” of exposed calcium carbonate skeleton.

Stony coral tissue loss disease (SCTLD) is one of the biggest threats to corals in Cozumel

Stony coral tissue loss disease (SCTLD) reached Cozumel in 2018, carried by cruise ships from one port to another. In just a year over 60% of Cozumel's corals died. Some coral species went entirely extinct in the wild.

There is no definitive cure to date, but the CCRRP have conducted studies and determined that covering coral in antibiotic paste has a 50% chance of stopping the disease from spreading to adjacent colonies.  We also growing Pillar corals (Dendrogyra cylindrus) and other at risk species in our aquarium and garden to help these species alive until either the surviving populations gain immunity or an more effective treatment is found.

Threats to Coral
Divers planting coral reefs

White Band Disease came from Florida to the Caribbean in the 1980s. Unlike SCTLD, white band disease largely targets Elkhorn (Acropora palmata) and Staghorn (Acropora cervicornis) corals, two of the most common reef building species in Mesoamerica. With a 95% mortality rate, white band disease literally destroys the reef’s foundation. 

Warming water conditions and exposure to untreated wastewater are the main contributors to outbreaks of white band disease. We are still looking to find an effective and distributable cure, but some experiments of increasing colonies sea urchin populations have made them more resilient.

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