What are the common symptoms of coral reef injuries. How to provide first aid for coral cuts. What is the typical healing time for coral scrapes. How to prevent complications from coral reef infections.

Understanding Coral Reef Injuries: Causes and Mechanisms

Coral reef injuries are among the most common incidents encountered by divers and snorkelers. These injuries, often in the form of cuts and scrapes, can be more complex than they initially appear. The Divers Alert Network (DAN) reports receiving approximately one inquiry per week related to coral contact incidents.

Why are coral injuries unique? The answer lies in the structure of coral itself:

• Coral surfaces are covered with soft living tissues
• Underneath this soft layer is a rigid, abrasive structure
• When contact occurs, the soft tissue tears easily, introducing foreign material into the wound

This combination of factors can lead to a prolonged healing process, often confusing both patients and medical professionals due to its latent evolution.

Symptoms and Manifestations of Coral Cuts

The severity of a coral injury can vary widely, depending on several factors:

• Presence and amount of toxins in the coral
• Size and location of the abrasion
• Individual sensitivity of the injured person

Common symptoms of coral cuts include:

1. Burning sensation
2. Pain
3. Itching
4. Rash (particularly if contact was made with hydroid corals like fire coral)

In the case of fire coral injuries, blistering typically appears a few hours after contact. These injuries are known for their tendency to relapse, even after apparent healing progress.

Immediate First Aid for Coral Cuts

Proper first aid is crucial in managing coral injuries effectively. Here’s a step-by-step guide:

1. Scrub the cut vigorously with soap and water
2. Flush the wound thoroughly with large amounts of water
3. Apply a half-strength solution of hydrogen peroxide in water, then rinse again
4. Apply a thin layer of antiseptic ointment
5. Cover the wound with a dry, sterile, non-adherent dressing

If no ointment or dressing is available, the wound can be left open. It’s important to clean and re-dress the wound twice daily to prevent infection and promote healing.

Advanced Treatment and Wound Care

For wounds that develop a crust, a wet-to-dry dressing technique can be effective:

1. Cover the wound with a dry sterile gauze pad
2. Soak the pad with saline or diluted antiseptic solution (1-5% povidone-iodine in disinfected water)
3. Allow the dressing to dry, then remove it
4. Repeat this process once or twice daily until the dressing becomes non-adherent

This method helps remove dead and dying tissue, promoting faster healing. Once the wet-to-dry dressings become non-adherent, resume regular wound dressing as described earlier.

Recognizing and Managing Complications

While most coral cuts heal without significant issues, it’s crucial to be aware of potential complications. Watch for signs of infection, including:

• Extreme redness
• Red streaks on the extremity
• Increased pain
• Fever
• Presence of pus
• Swollen lymph glands

If any of these symptoms occur, consult a healthcare professional promptly. They may recommend starting an antibiotic course, particularly if there’s a risk of Vibrio bacteria infection.

Coral Poisoning: A Serious Complication

In some cases, particularly with extensive abrasions or cuts from highly toxic coral species, coral poisoning can occur. Symptoms of coral poisoning include:

• Poor wound healing
• Continuous pus drainage
• Swelling around the cut
• Swollen lymph glands
• Fever
• Chills
• Fatigue

If you experience these symptoms, seek medical attention immediately.

Prevention: The Best Approach to Coral Injuries

While treatment is important, prevention remains the best strategy for dealing with coral injuries. Here are some preventive measures:

• Avoid contact with coral or any other living marine creatures while underwater
• Wear a wetsuit or dive skin for protection
• Carry a marine animal first aid kit during ocean dives
• Consider taking courses in marine life identification and first aid

By following these precautions, you can significantly reduce your risk of coral injuries and enjoy safer diving experiences.

Healing Time and Long-Term Care for Coral Cuts

The healing time for coral cuts can vary significantly, ranging from a few weeks to several months. This extended healing period is due to the unique nature of coral injuries, which often involve foreign material and potential toxins.

Factors affecting healing time include:

• Depth and severity of the cut
• Location of the injury
• Individual’s overall health and immune system
• Promptness and effectiveness of initial treatment

For optimal healing:

1. Keep the wound clean and dressed
2. Avoid re-exposure to marine environments until fully healed
3. Monitor for signs of infection or delayed healing
4. Consider follow-up with a healthcare provider for persistent issues

Dealing with Persistent Symptoms

In some cases, coral cuts may lead to the formation of granulomas – small, raised, tender bumps that can persist for weeks or months. These occur when debris from the original wound remains in the tissue, causing the body to mount an ongoing immune response.

If granulomas develop:

• Avoid scratching or irritating the area
• Continue to keep the area clean
• Consult a dermatologist if the granulomas persist or cause significant discomfort

Special Considerations for Different Types of Coral Injuries

Not all coral injuries are created equal. Different types of coral can cause varying reactions and require specific considerations in treatment.

Fire Coral Injuries

Fire corals, despite their name, are not true corals but belong to the class Hydrozoa. They contain nematocysts, which can cause envenomation upon contact. Fire coral injuries have some unique characteristics:

• Blistering typically appears hours after contact
• Symptoms may resolve in a few days but often relapse within 1-2 weeks
• Treatment may include topical corticosteroids to manage inflammation

Stony Coral Injuries

Stony corals have a hard, calcium carbonate skeleton that can cause deep abrasions. These injuries require thorough cleaning to remove all coral fragments from the wound.

Soft Coral Injuries

While generally less abrasive than stony corals, soft corals can still cause irritation and introduce toxins into the wound. Proper cleaning and monitoring for allergic reactions are crucial.

The Role of Marine Environment in Wound Healing

Coral cuts present unique challenges compared to typical outdoor abrasions due to the marine environment. Several factors contribute to this:

• Presence of marine microorganisms in the wound
• Potential for ongoing exposure to saltwater
• Risk of secondary infections from marine bacteria

These factors underscore the importance of proper wound care and the need for vigilance in monitoring healing progress.

Impact of Water Quality on Healing

The quality of the water where the injury occurred can significantly impact healing:

• Areas with high pollution levels may introduce additional contaminants into the wound
• Warm water environments can increase the risk of certain bacterial infections
• Brackish water injuries may require different treatment approaches than those from open ocean environments

When seeking medical attention, it’s important to inform healthcare providers about the specific environment where the injury occurred.

Enhancing Recovery: Nutrition and Lifestyle Factors

While proper wound care is crucial, overall health and lifestyle factors can also play a significant role in recovery from coral injuries. Consider the following to support healing:

Nutritional Support

• Increase protein intake to support tissue repair
• Consume foods rich in vitamin C to boost collagen production
• Ensure adequate zinc intake, which is crucial for wound healing
• Stay well-hydrated to support overall health and healing processes

Lifestyle Adjustments

To promote optimal healing:

• Get adequate rest to allow your body to focus on healing
• Avoid smoking, which can impair wound healing
• Limit alcohol consumption, as it can interfere with the healing process
• Manage stress levels, as chronic stress can negatively impact immune function

Physical Activity Considerations

While recovery is ongoing:

• Avoid activities that could re-injure the affected area
• Engage in gentle exercise to promote circulation, but avoid excessive sweating near the wound site
• Consider low-impact activities like swimming in chlorinated pools once the wound has started to heal (but avoid ocean swimming until fully healed)

Long-Term Effects and Follow-Up Care

While most coral injuries heal without long-term consequences, some individuals may experience prolonged effects. It’s important to be aware of potential long-term issues and know when to seek additional care.

Potential Long-Term Effects

• Scarring: Depending on the depth and severity of the cut, scarring may occur. Proper wound care can minimize this risk.
• Hyperpigmentation: Some individuals may experience darkening of the skin at the injury site, which can persist for months or even years.
• Chronic Sensitivity: In rare cases, the injured area may remain sensitive to touch or temperature changes long after healing.
• Keloid Formation: Some people are prone to developing keloids, which are raised, overgrown scars that extend beyond the original injury site.

When to Seek Additional Medical Care

Consider consulting a healthcare provider if:

• The wound shows no signs of improvement after several weeks of home care
• You experience recurring infections or inflammation at the injury site
• There’s persistent pain, itching, or other discomfort that doesn’t resolve with time
• You notice unusual growths or changes in the skin around the healed wound

Follow-Up Care Options

Depending on the nature and severity of long-term effects, follow-up care may include:

• Dermatological treatments for scarring or pigmentation issues
• Physical therapy for injuries that have affected mobility or caused chronic pain
• Allergy testing if there are concerns about developed sensitivities
• Psychological support for individuals experiencing anxiety or distress related to the injury or its aftermath

Remember, every individual’s healing process is unique. While these guidelines provide a general framework for managing coral injuries, always consult with healthcare professionals for personalized advice and treatment, especially in cases of severe or persistent symptoms.

Coral Scrapes and Cuts – Divers Alert Network

Cuts and scrapes are the most common injuries incurred by divers and snorkelers. DAN receives about one inquiry a week related to someone who has come into contact with coral. A burning sensation, pain and itching are common and may also be accompanied by a rash. These injuries can have a latent evolution and take weeks or months to heal, confusing both patients and clinicians.

Mechanisms of Injury

Soft living tissues cover the surface of corals. In the case of stony corals, the rigid (abrasive) structure underneath makes the coral’s soft tissue easy to tear and get into the scrape or cut. Foreign material can prolong the wound-healing process since the different antigens and substances cause an acute inflammatory process and infection. Cuts and scrapes from sharp-edged coral and barnacles tend to fester and may take weeks or even months to heal. Granulomas can form if debris from the original wound remains in the tissue. The body attempts to remove it, resulting in an itchy rash or papule (small, raised, tender bump) that lasts for some time before the body eliminates it.

While most “raspberries” generally heal quickly, skin abrasions from a marine environment can sometimes be more challenging to treat than those we get from outdoor activities such as baseball or bicycling. Whether it is a coral, a rock or a wreck, they all share a common factor: They are covered by living marine organisms, which makes coral cuts and scrapes unique.

Manifestations

The extent of the reaction depends on the presence and amount of toxins, the size and location of the abrasion and the pre-existing sensitivity of the injured person. The most common manifestations are a burning sensation, pain and itching. A rash may accompany the injury if the coral is a hydroid, such as fire coral.

Most animals of class Hydrozoa become hydroids as a life stage. They are predominantly colonial, and while most of them are marine creatures, you can find a few species in freshwater environments.

Fire corals are cnidarians, so they contain nematocysts. Touching them with a simple rub can cause mechanical activation and envenomation. The manifestation is usually blistering, which typically appears a few hours after contact. They typically resolve in a few days, but it is quite common for these injuries to relapse within a week or two after what seemed to be healing progress. This delayed reaction is typical of these types of envenomations.

Prevention

When underwater, try to avoid contact with coral or any other living creature. Whenever possible, wear a wetsuit or dive skin to protect yourself if you are accidentally pushed into coral by another diver or a current. Ocean divers should consider a marine animal first aid kit for their travels. Ready supplies will speed up the time to properly administer first aid for injuries. Additionally, for divers who want to learn more about the various marine life injuries, there are courses in marine life identification, first aid courses and a variety of books and publications available.

First Aid

• Scrub the cut vigorously with soap and water, and then flush the wound with large amounts of water.
• Flush the wound with a half-strength solution of hydrogen peroxide in water. Rinse again with water.
• Apply a thin layer of antiseptic ointment, and cover the wound with a dry, sterile and non-adherent dressing. If you have no ointment or dressing, you can leave the wound open.
• Clean and re-dress the wound twice a day.
• If the wound develops a crust, use wet-to-dry dressing changes. Put a dry sterile gauze pad over the wound and soak it with saline or a diluted antiseptic solution (such as 1% to 5% povidone-iodine in disinfected water). Allow it to dry then rip the bandage off the wound. The dead and dying tissue should adhere to the gauze and lift free. The tissue underneath should be pink and may bleed slightly but should be healing. Change the dressings once or twice a day. Use wet-to-dry dressings for a few days or until they become non-adherent. Then resume the regular wound dressing described above.
• Look for any signs of infection: extreme redness, red streaks on the extremity, pain, fever, pus or swollen lymph glands. If you have any, consult a qualified health professional about starting an antibiotic. A possible Vibrio bacteria infection can cause illness and even death in someone with an impaired immune system (e.g., from AIDS, diabetes or chronic liver disease).
• Watch for coral poisoning, which can occur if abrasions or cuts are extensive or from a particularly toxic species. Symptoms include a wound that heals poorly or continues to drain pus, swelling around the cut, swollen lymph glands, fever, chills and fatigue. If you have these symptoms, see a physician.

Complications

The most frequent complications from non-stinging coral scrapes are inflammation (which leads to poor healing) and less commonly a secondary infection. Proper wound cleaning is crucial. If fire coral is the culprit, then a diluted acetic acid solution, such as household white vinegar, is a reasonable topical decontaminant and should be used as a soak to reduce the pain. Immersion in hot water can reduce the symptoms. Hot water is ideal, but you can use instant hot packs, cold packs or ice packs. Provide symptomatic treatment for the inflammatory response. Steroid creams are rarely helpful, and they can prolong a skin infection. If the inflammation is severe, you may administer systemic steroids in a moderate, tapering dose under the supervision of a trained medical provider. Oral antihistamines can sometimes help reduce the itching or burning sensation. 

Possible Complications of an Old Problematic Wound

It is not uncommon for divers to contact DAN concerned about a minor skin abrasion on their hands, knees or elbows that happened months ago and has not healed despite proper care. These chronic wounds often have a red and bumpy appearance, occasionally develop a crust and are usually painless. If common antibiotic ointments do not help, divers wonder if the cause may be a marine-specific pathogen.

Divers with an open wound, even a small cut or scrape, are at risk for skin infections. When an old problematic wound fits the descriptions above, it might have become infected with an opportunistic pathogen known as Mycobacterium marinum. Despite the name there are no marine-specific pathogens that affect humans. Some infections are more common in aquatic environments. M. marinum is responsible for a condition commonly known as fish tank granuloma, or aquarium granuloma.

The red and bumpy nodules, no larger than a centimeter, are granulomas — inflammatory immune cells trying to wall off the pathogen. Granulomas are usually isolated but can sometimes appear in small clusters. They are not necessarily painful. There may or may not be discharge from the wound.

Characteristics of

M. marinum That Affect Healing

• The pathogen is opportunistic. It causes infection only in the right conditions (environmental and patient-related), so it is often not considered as a potential culprit.
• It likes cooler temperatures, which is why these wounds tend to flourish in areas with lower body temperatures such as hands, knuckles, elbows and knees.
• Only specific antibiotics work, so the typical antibiotic treatments are usually unsuccessful.
• The life cycle is slow, which means treatments last a long time. Sometimes patients will abandon what could have been a successful treatment or doctors may look for other potential explanations for the symptoms.
• It requires specific culture media that a doctor would not ask for unless they suspected this pathogen. Standard culture results are often negative, which delays the diagnosis.

Allow your doctor to examine the wound and follow their standard procedures. The doctor will probably ask you how it happened or when it started. Tell them about the superficial abrasion in a marine environment. You may want to ask specifically if M. marinum could be the cause. Your doctor does not need dive-specific medical knowledge for this type of issue.

Fitness to Dive

Always take care of wounds and clean them thoroughly no matter the severity. The skin is our most effective and efficient means of immunological defense. A compromised wound can get seriously infected.

As a rule, treat wounds properly and let them heal before diving. This is particularly important before traveling to a remote location or one with limited local medical care capabilities. A skin lesion with the potential for infection might warrant a more conservative decision to stay ashore if you have such a trip planned.

Chronic skin lesions require specific consultation with your physician team before diving. Your doctor may prescribe treatment or a protective covering to prevent skin breakdown.

How To Treat Reef Cuts

Regardless of your experience, reef related injuries are not a matter of if…but when!

Reef cuts and infections are a big deal…They require immediate attention to avoid countless health problems.

Your surf trip will eventually become a nightmare if your reef cuts lead to infections that can adversely affect your overall health.

The coral reefs throughout Indonesia contain unusual nasty bacteria and toxins.
Foreign debris and coral spores embed themselves in the skin and tissue, acting as a source of infection, increasing pain, inflammation and prevent your wound from healing.

It’s a fact that reef cuts are one of the most difficult types of wounds to heal. Even the smallest, harmless-appearing reef cut or rash has a high chance of developing into a serious infection if not treated properly. We see it time and time again, surfers that are not properly prepared with reef cuts left ill-treated or in some instances untreated. Leading to an infection that not only puts a damper on your surf trip but can threaten your life.

Considering your most common injury is going to be a reef cut or laceration, you have to be prepared for treating, cleaning, and bandaging basic wounds with the right kind of first aid kit when surfing reefs.

What You’re Going To Need…

An irrigation syringe is a lightweight and easy tool to carry for the first step in disinfecting any wound.  You should use an irrigation syringe, and not your bare hands when irrigating any reef cut to prevent the spread of bacteria and infections. 

Tap water in Indonesia is not clean and the ocean water at this temperature harbours a lot of bacteria so use bottled water to first irrigate your wound. Bottled water is conveniently available in stores all around Indonesia. 

Used to clean around the wound. Carefully cover your finger with soap wipes to ensure that you don’t touch the surface of the wound. 

To sterilise tweezers, scissors, the area around the wound and assisting adhesive bandages to make better contact with the skin. You can also use bottled isopropyl alcohol if available.

When you are treating wounds yourself you need all the help you can get and high precision tweezers with an elbow are the top of the line when it comes to easily and effectively removing foreign debris from your wounds. DON’T get stuck with plastic tweezers or cheap tweezers that you can’t get an accurate pinch from, you’ll cause yourself more pain and become extremely frustrated.  Moreover, plastic or cheap tweezers aren’t always made from the best materials and using these in treating your reef cuts might only do more harm than good. 

Quality pair of stainless steel scissors to cut and shape adhesive tapes and bandages. Don’t forget to clean your scissors with alcohol before using them. A pair of high-quality scissors can be very useful when dressing cuts, which is why it’s best if you always include them in your first aid kit. 

A razor enables you to shave the hair around the wound and keep the area clean assisting adhesive bandages to make better contact with the skin.

Used to clean the wound thoroughly one last time to ensure any coral dust/spores are removed decreasing the likelihood of infection and delays in the healing process.

Mimics your body’s internal pH and is used in the final step when irrigating the wound to provide the cleanest environment possible.

An effective formula that contains three active antibiotic ingredients to stop the growth of bacteria, prevent infection and reduce pain and inflammation. WARNING; commonly used topical antiseptics (lime, hydrogen peroxide, iodine and alcohol) actually damage the tissue and irritates the wound delaying the healing process.

This revolutionary cellulose-based material accelerates the blood clotting process and is a must-have item in every surfing first aid kit. When the gauze comes in contact with blood it quickly transforms into a stiff gel, which fills wound voids, seals capillary ends and activates the clotting system saving you days or weeks of recovery time.

Wide area adhesive dressing that is especially suitable for use on frequently mobile and highly contoured parts of the body where most reef cuts occur. It provides a bacterial barrier that is permeable to air and water vapour with an excellent long term skin/wound friendly adhesion. It can be applied directly over the top of the wound with or without gauze and minimises any disturbances of blood circulation to speed up the healing process of reef cuts. Adhesive stretch dressings are some what the swiass army knife of wound dressings when it comes to reef cuts.

How To Treat a Reef Cut…

You’re first step for any kind of cut, reef or otherwise, is to irrigate, loosening and removing any foriegn debris from the wound. Since the tap water in Indonesia is not clean use bottled water to first irrigate your wound flushing out as much foreign debris as you can. Save the saline solution for last unless you have a large supply of it.

Using an irrigation syringe irrigate the wound further for an extended period of time washing out as much bacteria as you can. Then clean around the wound with soap wipes.

Coral contains a range of very nasty and unusual bacteria and toxins. Tiny coral cysts enter the wound and get embedded in tissue to not only cause wound healing delay, but pain and recurrent swelling for a long time. So naturally the first major rule is thorough, extended cleaning. The longer the better! Don’t do what we have seen a million times: “Oh, that’ll do mate.” No it probably won’t. Do it again, thoroughly.

Use tweezers (first sterilise the tweezers with alcohol wipes) to remove any foreign debris from the wound that still appear after washing. It is important to get any remains of the reef or coral dust out of the wound as mentioned above. 

Take your time doing this as thoroughly as possible, removing any dead skin with sterile equipment along the way. It is a major step to speeding up the healing process. 

We can’t stress this enough, do it right the first time, because once the swelling and infection sets in, it becomes increasingly difficult to remove foreign objects.

Use the razor to shave any hair around the wound in preparation for covering the wound. This greatly enhances how well any adhesive bandages stick to the skin, keeping the wound cleaner for longer and speeding up the healing process.

Fill the irrigation syringe with saline solution or simply use saline solution straight from the bottle and rinse the wound while lightly cleaning with a wound cleaning sponge.

Clean, dry and degrease the area around the wound with alcohol wipes. This not only rids of bacteria but dries the skin for applying an adhesive stretch dressing.

Treat the wound with a triple antibiotic ointment ensuring any remaining bacteria from the cleaning or debriding process doesn’t take root in your injury, preventing infection and assisting in relieving pain and inflammation.   

While commonly used antiseptics such as lime, hydrogen peroxide, iodine or rubbing alcohol into the wound does work to kill bacteria it also damages the tissue, irritates the wound and delays the healing process.

Use Hemostatic Gauze to control any remaining bleeding and active the blood clotting system. With scissors cut and shape the hemostatic gauze to shape to match the wound and apply directly to the wound with pressure.

Hemostatic gauze is commonly used by armed forces and hospitals to address gunshot wounds. When the Hemostatic Gauze contacts with the wound it quickly transforms into a stiff gel, filling the wound, sealing capillary ends and activating the blood clotting system saving you days or weeks of recovery time.

Prepare an adhesive stretch dressing by cutting it to the length you need, then cutting it to the desired shape and apply it directly over the top of the wound and/or hemostatic gauze when the area around your wound is completely dry. 

Hot tip: round the corners of the dressing with scissors so there are no corners that may start to peel back off the skin.

Raise the limb. Swelling, even if you can’t see it, can delay healing, especially in areas of poor circulation. Keep your arm or leg up to the level of your heart or higher in the first few hours.

This is indicated by red spreading edges around the wound which can lead to fever, severe illness and even death. If you see this, you need urgent medical help. Do not delay even if you are in a remote place — you will need antibiotics or change to a different antibiotic if you are on one already. Get some medical advice even if it’s on the phone to work out which antibiotic is best and assess your condition if you’re getting ill and febrile.

Seek urgent medical attention if…

1. The wound is large or deep.
2. The edges of the wound do not stay together.
3. It is not possible to clean the wound properly or remove all debris. 
4. Symptoms of infection occur (fever, increasing pain or redness, or discharge from the wound).
5. If blood is spurting from the wound or if applying pressure to the wound does not stop the bleeding!

Reef cuts can be challenging to treat, which is why you should exert effort to avoid such wounds whenever possible. This is especially important if you’re fond of spending time at the beach and in the surf.

If you like to explore reefs when you’re not surfing investing in and wearing some water aerobic shoes is one way of avoiding reef cuts out of the surf in the future. Wearing a dive suit and maintaining a respectful distance from the reefs can also help whenever possible.

The Surfers First Aid Kit is perfect for treating reef cuts. Tried and tested by surfers to meet the needs of surfing, not only in Indonesia but around the world!

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The Surfers First Aid Kit

“Not having a good First Aid Kit on hand places you at serious risk”.

Other Items You’ll Need…

Butterfly Stitches

Also known as Steri-Strips or butterfly bandages, are narrow adhesive bandages that are used instead of traditional stitches (sutures) to close small, shallow cuts.

Splinter Probe

Sea urchin spines have a tendency to wander into the worst parts of the body, regardless of how well you protect yourself. Your best bet is to use a splinter probe to efficiently remove the spine as soon as possible.

Sports Tape

Not your typical rigid strapping tape but a pliable sports tape with stretch to fit the curves and corners of your body securely where a lot of reef cuts occur.

Cotton Bud Swabs

Versatile tool that has many uses in your first aid kit.

The Surfers first aid kit…

Surf Indonesia has thoughtfully packaged these items and more into a conveniently purpose-built first aid kit for surf travel.

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A disease that kills coral reefs

In the fall of 2014, something strange began to happen to corals growing near Miami. Deathly whitish spots began to appear on the pink skeleton of coral polyps, outwardly similar to a huge brain. They grew and grew until they devoured everything, leaving only lifeless limestone debris. Seven years have passed since then, but researchers still cannot determine what kind of mysterious disease struck the corals of Miami.

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A mysterious coral infestation began about 270 km off the coast of Florida. Later, the largest coral infestation in the world formed there. All research organizations, from the National Oceanic and Atmospheric Administration to the universities of Florida, have joined the fight against this coral killer.

The problem is still complicated by the fact that the heating of world waters is increasing every year. This alone leaves temperature-sensitive polyps vulnerable, so the third largest coral reef on the planet may not be in good enough shape to deal with an infection on its own.

Biologists are sure that “white syndrome” is a bacterial infection. In this case, scientists could take samples of infectious agents and infect corals with them under controlled laboratory conditions.

But there is one problem. Like the human body, corals are full of a wide variety of bacterial microbiomes, even in their healthy state. It is very difficult to isolate a particular species and recognize a pathogen in it under these conditions. In addition, the disease behaves unpredictably: it managed to hit reefs that are physically separated from each other by a very large distance, which was an unpleasant surprise for scientists. How? Nobody understood.

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Although algologists cannot investigate the pathogen, they do not lose heart and make more and more attempts: they take samples of infected corals, try to disinfect them with antibiotics and even ordinary bleach, and observe exactly how the disease progresses in order to stop its further spread .

Mote Marine Lab, a private marine research center in Florida, is growing brain corals to replace the hardest hit parts of the reef. So far, it is the brain corals that are resisting the infection, but this does not help their relatives.

Interestingly, a similar algal epidemic has happened before: in the 1980s, a similar disease hit the reef, leading to the almost complete extinction of the species Acropora cervicornis and Acropora palmata , which after that were listed in the Red Book. Over the past 30 years, scientists have learned a lot more about corals and even learned how to breed them artificially. It remains to be hoped that this will help them eventually save the reefs from complete destruction.

Symbiont crustaceans are not infectious for corals

Copepods, living in corals, do not affect the microbes of their hosts.

Caribbean sea fan coral Gorgonia ventalina (Alcyonacea). (Photo: V. N. Ivanenko, Moscow State University)

Pink galls (marked with arrows) on a Caribbean coral caused by copepods of the genus Sphaerippe. (Photo: VN Ivanenko, Moscow State University)

Female copepod of the genus Sphaerippe, ventral view, image from a scanning electron microscope. (Photo: VN Ivanenko, Moscow State University)

Model species of the Red Sea reef-building coral Stylophora pistillata. (Photo: VN Ivanenko, Moscow State University)

Changes in processes (marked by arrows) on the coral Stylophora pistillata caused by copepods of the genus Spaniomolgus. (Photo: V. N. Ivanenko, Moscow State University)

Female copepod of the genus Spaniomolgus, ventral side view, image from a scanning electron microscope. (Photo: V. N. Ivanenko, Moscow State University)

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Corals, like humans, have their own bacteria, which form complex and diverse communities. The bacteria that help corals resist disease largely determine whether a coral colony survives or not.

But corals – like us – are regularly invaded by foreign bacteria that can affect the health of their microbial community and thereby disrupt the coral’s well-being. Moreover, such alien bacteria often turn out to be simply pathogenic. Copepods, or copepods, can be sources of infection. These crustaceans, feeding on tissues and secretions of corals, live in special neoplasms – galls, which, presumably, appear due to bacteria that came with copepods. Some of the copepods are also known to actually carry infections; it can be assumed that the pathogens that the crustaceans bring with them to the coral colony help them distract the colony’s defense mechanisms from themselves.

But if bacterial infections of corals do come along with copepods, then the bacterial composition of the diseased area of ​​the colony should be similar to that of crustaceans and should be different from the bacteria of the healthy area of ​​the coral colony. To check whether this is true or not, researchers from the Moscow State University. M. V. Lomonosov, Institute of Genetics of the Russian Academy of Sciences, Institute for Information Transmission Problems (IPPI) named after. A. A. Kharkevich RAS and other Russian scientific centers, together with colleagues from the Netherlands and Saudi Arabia, analyzed the microbial communities of corals and copepods. Microbial communities were compared by the 16S RNA gene, a ribonucleic acid that is part of the ribosome, a complex molecular machine that assembles proteins from amino acids. Ribosomal RNAs are quite conserved, that is, they change little over the course of evolution, so they are useful to see the differences between large groups of living organisms – especially when it comes to creatures as changeable as bacteria.

For research, we took two copepod-coral systems recently discovered by marine biologists of Moscow State University: the Caribbean sea fan coral Gorgonia ventalina with copepods of the genus Sphaerippe living in it and a model species of the Red Sea reef-building coral Stylophora pistillata with copepods genus Spaniomolgus . There were indeed differences in the composition of the microbial community between these two coral-copepod systems; also differences were visible within each system. But besides, healthy corals, diseased corals (which had galls) and copepods differed from each other in terms of bacteria more than both systems in general differed from each other. In coral galls, microbial communities were found to be similar to those of healthy corals, although they differed somewhat from those in structure.

An article in Scientific Reports states that copepod microbes are unlikely to have any tangible effect on the microbial community of the coral – at least, no clear evidence of this could be found. Symbiont crustaceans probably somehow influence the formation of gall tissue, but this influence is unlikely to come through bacteria. In the future, according to Vyacheslav Ivanenko, a leading researcher at the Laboratory of Morphology, Ecology and Systematics of Invertebrates, Faculty of Biology, Moscow State University, it will be interesting to see the microbial composition of other invertebrates that enter into symbiosis with each other – the chosen research strategy can be in the study of symbiotic relationships with a variety of properties.