Corals in danger… Beginning of a foretold death

Corals in danger… Beginning of a foretold death

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The future of corals is not as beautiful and bright as the many shapes and colors of these stone structures, symbiosis of polyps and algae, if urgent measures are not taken to protect them from climate change, pollution and overfishing. This event brought together some 2,500 scientists, experts and government officials from 114 countries.

The future of corals is not as beautiful and bright as the multiple shapes and colors of these stone structures, symbiosis of polyps and algae, if urgent measures are not taken to protect them from climate change, pollution and overfishing.

2008 was designated as the International Year of Coral Reefs, according to a resolution approved by members of the International Coral Reef Initiative (ICRI), during a meeting held in Cozumel, Mexico, in October 2006. The agreement, signed By 17 countries and 30 organizations, it is also supported by three important environmental Non-Governmental Organizations (NGOs): the Spanish WWF / Adena and Nature Conservancy and the North American Conservation International. But to date nothing to prevent its destruction has yielded noticeable results.

Marine corals are colonial animals belonging to the phylum Cnidaria, class Anthozoa. Colonies are made up of thousands of zooid individuals and can reach large dimensions.

The term coral has no taxonomic meaning and is imprecise; it is often used to designate anthozoans that generate a hard calcareous skeleton, especially those that build branched colonies; but it is also common to call coral to species with compact colonies ("brain" coral) and even with a horny and flexible skeleton, such as gorgonians.

The second largest coral reef in the world, the Mesoamerican Reef along the coast of Mexico, Belize, Guatemala and Honduras, is located in the Caribbean Sea, extending for more than 700 km from the Yucatan Peninsula to the Islands of the Bay on the north coast of Honduras. Even though it measures a third of the size of the Great Barrier Reef, Australia's Great Barrier Reef, the Mesoamerican Caribbean Reef is home to a great diversity of beings, including 60 types of corals and more than 500 species of fish.

In 1998, the World Wide Fund for Nature (WWF) identified the Mesoamerican Caribbean reef as a priority ecosystem and an eco-region of global importance, thus beginning a long-term reef conservation effort.

Situation in Quintana Roo

Our corals in the area of ​​the State of Quintana Roo, are distributed in ecosystems and are threatened by two types of causes: natural and anthropic (man as origin). In the former, it is worth highlighting the effects of the waves generated by the hurricanes that hit this area of ​​the Mexican Caribbean. They are also affected by sudden changes in temperature and salinity of the water, two key environmental characteristics that directly affect animals as a whole, and predation by other organisms such as fish, snails and starfish, also harmful to this wonder of colonial aquatic animals. On these reefs there is rapid growth of algae that can kill corals by competing with each other for light and space. But corals have evolved over millions of years to adapt to improve their defense against natural causes. A sample of these adaptations are the high fecundity, the production of nematocysts and spreading their polyps only at night; very successful so far.

Unfortunately there are other threats for which they have not adapted, the so-called anthropogenic effects such as pollution, destruction of mangroves, soil erosion, deforestation, overfishing, indiscriminate extraction, excesses in marine tourism and climate change are some of the factors that could destabilize the ecosystem. Pollution can affect corals in various ways, depending on the pollutant in question that is occurring, so we have as an example:


The rise in temperatures, due to climatic changes, causes coral bleaching, a result of its response to stress, which makes them weaker and more fragile against diseases.


When the waters absorb increasing amounts of carbon dioxide from the atmosphere, the acidity of the seawater increases, which causes a negative impact on the capacity of the wastewater coming from the continental part as a result of mismanagement this water rich in potassium and nitrogen reaches the seas and drives the excessive growth of algae, one of the deadly enemies of coral.

Deforestation also has a negative influence. When lands are depopulated with trees, the land slides more easily in the rain and goes to the coastal waters. This causes tiny sediment particles to float for a long time in the sea and block the sunlight that must reach the corals and seagrass beds for them to survive.


Spearfishing, for example, causes harm by selectively removing species from the food chain of these ecosystems. Misused ship anchors destroy centuries of coral growth and important fish communities in seconds.

Careless swimmers and divers who visit reefs cause damage by standing on or touching corals. Some even tear off pieces of stone or collect sponges and shells to keep as souvenirs, not considering that they later end up decomposed in travel bags.

Oil spills disrupt the growth rate and reproduction systems of corals. Dispersants used after an oil spill only increase the threat and can even wipe out extensive coral communities.

Trawling also contributes to the destruction of corals. Under these conditions, they are easy prey for diseases, such as the so-called white band that has decimated the population of staghorn and elkhorn corals.

Areas of Jamaica, the Dominican Republic and Mexico that have been hit hard by hurricanes in recent years have lost large coral communities. There is a deterioration in the coverage of these ecosystems at a global level, but the problem in the Caribbean is that there are no conditions for them to recover.

Only 25 percent of the coral communities in the Caribbean are in good condition, according to an International Symposium on Coral Reefs, held in mid-July this year, in Fort Lauderdale, 50 kilometers north of Miami. This event brought together some 2,500 scientists, experts and government officials from 114 countries.

The main polluting sources of the coral communities in this area of ​​the Mexican Caribbean are uncontrolled wastewater discharges from human settlements, soil erosion and fishing.

The increase in sediment in coastal areas, where it has been deforested, there are hotel buildings, housing estates and roads, causes the mortality of corals. It is very difficult for corals to survive these conditions. The murky waters prevent light from penetrating the corals, which suffocate, become ill and as a result die.

Mangroves maintain the solid ground and when these are removed erosion is caused, thus carrying sediments to the reefs and causing their destruction. The agencies or people who are in charge of construction, or deforestation, should do a thorough investigation of the environmental consequences, before starting such projects. It is important to conserve and protect our natural resources, since they have an important economic value both for the present and for the future.

Oil pollution

Oil spills affect the growth rate and reproduction systems of corals.

This impact is compounded by dispersants used after a spill, as they increase threats and can even kill them. Fuel runoff from ships also causes damage: in 1998, the ship Emily Cheremie destroyed more than 400 meters of reef off the coast of Quintana Roo. After describing oil pollution, it should be noted that any substance that affects the clarity of the water, such as excess sedimentation caused by dredging of the coast and erosion caused by deforestation, will affect zooxanthellae and their ability to photosynthesize. The used water and fertilizers increase the amount of organic matter and therefore cause eutrophication in the water. This stimulates the growth of algae that suffocate the polyps by growing faster than the corals, and compete for space on the sea floor with them. Chemical or biological contaminants can be toxic and kill corals. The discharge of hot water from power plants is as lethal as any poison since the corals are adapted to the stable temperatures of the tropics.


The growth of tourism activity has damaged reefs with sewage discharges and toxic pollution. Boats that drop anchor on reefs or run aground can destroy coral over a hundred years old in a matter of seconds, dumping trash or upsetting the balance of communities by catching too many fish and jeopardizing the reproductive capacity of the fish. populations. Some evidence that reefs may be in danger has been reported in recent years. The existence of careless divers, can touch and break the coral; Tourists are also responsible for the enormous growth in the trade in marine curios, especially endangered species such as black coral. In addition to being an irreplaceable habitat, reefs are natural breakwaters that repair themselves and protect the coastline, at no cost to man. Coral reefs provide food and protection for countless marine creatures, such as urchins, hawksbill turtles, crabs, lobsters and a long etcetera.

Both natural and man-made alterations can affect the complex food chain that has developed around the reef. In order to address these issues and protect reefs, we must continue to act.

Global climate change

The response of these ecosystems to climate change is known as coral bleaching.

When faced with extreme and prolonged stress due to the warming of tropical waters, the coral expels the algae (zooxanthellae) that live in its tissues, thus losing its natural color and taking on a whitish color; losing its association with the algae, the coral dies. This has been associated with the mortality of many coral colonies that sometimes seem to recover naturally. Black band disease has been described as necrotic tissue that grows in corals and appears to be caused by the cyanobacterium Phormidium corallyticum. This phenomenon has been described in many tropical areas including the Caribbean.

In the opposite direction, the corals absorb the CO2 dissolved in the water and incorporate it into the reefs. In this way, they help reduce the accumulations of this compound in the atmosphere and reduce the risks of global warming.

What is the current problem?

• Human activities threaten 2/3 of the Caribbean coral reefs, placing 1/3 at high risk.
• About 9,000 km2 of coral reefs are threatened by increased sedimentation and pollution related to land-based activities.
• Coastal zone development, including construction, urban runoff, tourism development, and wastewater discharge threatens 1/3 of the Caribbean reefs.
• Treated wastewater represents less than 20% of the total wastewater generated in the Caribbean.
• Only 1/4 of the hotel and resort wastewater treatment plants are in good working order.
• In 2006, 3/4 of the treatment plants operated by hotels and resorts did not meet the effluent discharge criteria.
• In the Caribbean, daily water consumption per tourist is about 300 liters / day, which is approximately 3 times the per capita demand of domestic consumers.
• The development of coastal areas as a result of population growth and intensive tourism, together with overfishing, threatens more than 80% of the reefs in the Caribbean.
• 36% of the coral reefs in the region are less than 2 km away. of human settlements.
• Increases in the population density of coastal areas leave reef resources susceptible to exploitation as a means of subsistence and livelihood for riparian inhabitants.
• Overfishing is the most widespread direct human threat to reefs, endangering 60% of them.
• Overfishing represents the greatest threat to reefs in the Eastern Caribbean, followed by coastal development, sedimentation, and pollution.
• During the last decades the coral reefs of the Caribbean have evolved from a state
dominated by corals to one dominated by algae.
• Sources of marine pollution, such as the discharge of sewage from cruise ships and other vessels and leaks and spills from the oil infrastructure threaten 15% of the reefs in the region.
• In the last 20 years, cruise tourism has quadrupled worldwide, with 58% of global cruise passengers occupying the Caribbean cruise industry.
• Typical cruise ships generate a daily average of 2,228 gallons and 278.5 gallons of oily bilge and garbage water respectively.
• The anchor of a cruise line can ruin up to 200 km2 of the ocean floor through direct physical damage.
• The planet's average temperature has increased by 6-8 ° C in the last 100 years, leaving corals more susceptible to bleaching.
• Caribbean reefs provide a net economic value added for goods and services between US $ 3.1 billion and $ 4.6 billion from fisheries, dive tourism, and coastal protection.
• Annually, tourism contributes an estimated US $ 105 billion to the Caribbean economy.
• In at least eight Caribbean countries, tourism represents more than 30% of GDP.
• The earnings left by international tourists in the Caribbean amounted to US $ 25,500 million in 2000.
• In 2000, approximately 3.6 million divers visited the Greater Caribbean, representing an estimated US $ 4.7 billion in gross expenditures.
• In 2000, the annual net benefits of dive tourism in the Greater Caribbean were estimated at US $ 2.1 billion.
• About half of all dive tourism in the Caribbean takes place in marine protected areas.
• Approximately 21% of the Caribbean coastline is protected by coral reefs.
• The annual benefit of coastal protection from healthy reefs is estimated between US $ 740 million and US $ 2.2 billion per year.
• In the Eastern Caribbean, 70% of the monitored beaches eroded between 1985 and 1995.
• By 2050, 10-20% of the current coastal protection services for the reef could be lost in more than 15,000 kilometers of coastline.
• The net value of the loss of benefits from coastal protection by reefs could range between US $ 140 - US $ 420 million a year, in the next 50 years.
• Continued reef degradation could reduce annual net income from coral reef fishing by between US $ 95 million - US $ 140 million per year by 2015.
• Net benefits from tourism, fisheries and coastal protection could be reduced due to coral degradation by an estimated US $ 350 - US $ 870 million per year.

How we can protect coral from certain death

- Always build behind the active dune of the beach to avoid erosion and that sediments do not reach the nearby reefs.
- Do not build hotels, marinas and human settlements in places near coral reefs to avoid risks of contamination and extraction of organisms.
- Protect coastal lagoons as flood basins (do not fill them). These lagoons can avoid or reduce the abrupt and abundant arrival of sediments and pollutants to the reefs during extreme events of rainfall or waves. The fill material can pass into the sea during such extreme events, or in the long term, with rising sea levels.
- Take care of the coastal vegetation to avoid erosion and not increase the arrival of sediments to the nearby reefs.
- Give priority to the reforestation of riverbanks and damaged mangrove coasts, as it can be done more expeditiously than the reforestation of large hydrographic basins, and they also constitute the last land-water frontiers.
- Do not divert water courses (rivers, channels, streams, runoff) to places where there are nearby reefs.
- Do not dump wastewater or water not treated in a tertiary way, in wells of the coastal karst. Waters polluted or laden with nitrogen and potassium nutrients can have submarine outlets on reefs.
- Employ fishing gear that is not harmful to the habitat, sustainable fishing quotas, protected areas of exclusion to recover declining or depleted resources (such as breeding or nursery areas, or protection of adults), seasonal breeding closures, limited fishing licenses, adjusted to the estimated and monitored capacities of ecosystems, and prohibit underwater shotgun fishing in protected areas or tourist diving.
- Do not fish in tourist diving areas, or in protected areas that, due to their category, require it.
- Regulate and strongly control the export of ornamental fish in tourist diving areas and in protected areas that, due to their category, so establish.
- Control or prohibit (as appropriate) the extraction, sale and export of articles made with material from rare, endangered or threatened species
- Prohibit the use of diving gloves or shoes to avoid touching or hitting corals or other reef organisms with their hands and feet. Tourists must wear a float vest for snorkeling. If possible, it is recommended that they do not use frog legs or that they be bare-heeled to avoid standing on these marine structures
- Testing means to stimulate the reproduction of herbivorous species and control the growth of algae on reefs. An example of this can be areas of artificial concentration of black urchins (Diadema antillarum) to facilitate the fertilization of the eggs released by them into the water. For this, protected areas and tourist diving can be included. In the latter case, the concentrated urchins could also rid the reefs of excess algae, which would increase their beauty and development. The work can be carried out by personnel of the areas and by volunteers.
- Educate children, adolescents and relevant decision makers about the values, functions and vulnerability of coastal ecosystems, as well as about the concept of sustainable development.
- Evaluate and monitor the health status of reefs and the impact of economic activities on these ecosystems to adopt the pertinent measures.
- Urgently deploy mooring buoy systems on coral reefs frequented by tourists and fishermen to avoid destroying the anchors.
- Demand the requirement of the Environmental Impact Study document for the approval of any investment license that may damage coastal ecosystems and specifically reefs.
- Ensure that environmental licenses are not issued in a timely manner, but within a comprehensive context of strategic planning within the area of ​​influence of the construction site.
- Comply with the tourist diving load limits in accordance with the regulations (less than 4,000 divers / site / year, as a precaution) and establish monitoring of the results to decide whether to maintain, increase or reduce the load.
- Avoid interpretive trails, as they are conceived in the terrestrial environment, so that visitors do not repeatedly dive along the same routes in the same place. Each place must be visited with different routes so that there are no dead or deteriorated reef "paths". Underwater labels cannot be placed, as attempting to read them can cause damage to nearby organisms. Demonstrative information should be given to the visitor before entering the water (eg video chat or slides).
- Prevent diving near bleached corals.


Juan Acosta Giraldo Doctor in Biological Sciences, Director of the DISAM Consulting GROUP.

Karla Lorena Gaytan Aguilar Architect, Land Registry Office, Honorable City Council of Solidarity.

Gea Ubilla Ortiz Professor, President of Origin Quintana Roo AC.

Video: Coral reef fish danger - Blue Planet - BBC Environment (June 2022).


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