Coral bleaching in marine aquariums – causes and prevention
Coral reefs – natural works of art threatened by bleaching
The multitude of colors, shapes and formations makes quite an impression even on people who are not aquarium and underwater life enthusiasts. Unfortunately, from year to year we can hear more and more about the so-called bleaching of coral reefs. This is a process of loss of color by corals, which in extreme cases can lead to loss of tissue and dying of entire colonies. The reason for this condition is the ongoing climate changes such as rising temperatures and ocean acidification.
Does coral bleaching also apply to home aquariums?
Unfortunately, coral reefs in our homes are not free from this problem. Although in home aquariums we do not face the problem of climate change, so unfortunately there are situations, leading to the destruction of a long-built coral reef in our aquarium in a short period of time.
Causes of coral bleaching in marine aquariums
Equipment failure and aquarist mistakes
These problems usually arise as a result of equipment failure or negligence on the part of the aquarist. Skipping weekly water changes, damaged or improperly set-up equipment, and mistakes in supplementation can effectively destroy all the effort we have put into caring for our aquarium. This manifests itself in the reluctance of corals to polyps, a change in color, or, ultimately, loss of tissue. An early diagnosis of the problem gives us a chance to improve the situation, but such problems are better avoided, as fighting them can be very difficult.
Coral bleaching and stress – process
Coral bleaching in aquariums is a process that begins with stress. As a result of the stress, the coral loses its symbiotic algae – zooxanthellae. Zooxanthellae are microscopic algae that live in the tissues of the coral and provide it with food through photosynthesis. They are also responsible for the coral’s colors.
When a coral is stressed, zooxanthellae are excreted from its tissues. Without zooxanthellae, the coral loses its vibrant colors and becomes white or pale. This process is called bleaching.
The bleaching of corals does not automatically mean their death. The coral can recover its zooxanthellae if conditions in the aquarium are restored to normal. However, if the stress lasts too long, the coral may die of starvation or infection.
It is important to remember that coral bleaching is a serious problem that can lead to coral death. Everything should be done to prevent coral bleaching in aquariums by maintaining stable conditions and providing them with proper care.
The main factors causing coral bleaching
1. Water temperature
This is one of the main parameters that should always be at a stable level. Therefore, it is important to periodically check the correct operation of the aquarium heater. It is worth installing a temperature sensor that will inform us in time about any deviation from the norm. This problem is particularly exacerbated during the holiday season, when the temperature in our homes rises. The optimal water temperature in marine aquariums should be between 24 and 27°C. Too high or too low a temperature can cause stress among corals. It should be remembered that even small fluctuations in temperature can cause this stress.
Therefore, it is very important to heat the brine prepared for water changes to a temperature close to that in the aquarium. This will not only allow us to get a correct reading of its salinity, but also avoid the stress caused by a sudden drop in temperature. The same is true when introducing new corals to the aquarium. That is why the acclimatization process is so important, which consists in gradually equalizing the water parameters (including its temperature) to those in the aquarium.
2. Nutrient deficiency
Corals depend on symbiotic algae (zooxanthellae) that live in their tissues and provide them with essential nutrients through photosynthesis. A lack of certain micronutrients, such as potassium and phosphate (PO4), can lead to coral starvation. Zooxanthellae will not be able to photosynthesize efficiently, leading to weakened corals and bleaching
3. Water pollution
Pollutants such as ammonia, nitrates and phosphates can be toxic to corals and lead to coral stress. These pollutants can come from excess food, organic waste or improper filtration and circulation. High levels of pollutants can disrupt the delicate aquarium ecosystem and lead to coral bleaching.
4. Overly intense lighting.
UV radiation, in particular, can damage coral tissues and lead to bleaching. It is important to use appropriate light sources and avoid overexposure. Keep in mind that corals need light for photosynthesis, but too much light can damage them. Corals may respond to excess light by shortening retracting polyps. This is easy to observe with LPS corals.
5. Improper acclimatization or lack thereof.
Moving corals from one aquarium to another or changes in their environment can cause stress, which can also lead to bleaching. Ensure stable conditions for corals and avoid frequent changes in their environment. When buying a new coral, remember to dip it and acclimatize it slowly and gradually. The best way to do it is drip acclimatization, which very slowly equalizes the water parameters of the new coral with those in our aquarium. Few factors affect corals as adversely as sudden jumps in parameters.
6. Diseases
Corals can be susceptible to various diseases that can lead to bleaching. The stress of the disease weakens corals, which can result in the loss of coral tissue. Regular observation of underwater life gives us the opportunity to quickly diagnose the problem and undertake appropriate treatment.
How to protect against coral bleaching?
To minimize the risk of coral bleaching in a marine aquarium, you should:
1. Regularly monitor water parameters
Temperature, pH, KH, and levels of magnesium and calcium, as well as nitrate and phosphate, should be monitored regularly. Any deviations from the norm should be corrected gradually, so as not to subject corals to the stress of parameter spikes. It is also worth conducting more specialized water tests with ICP tests, which give us an accurate idea of the situation in the aquarium.
2. Carry out appropriate supplementation of micronutrients
Provide corals with the necessary nutrients to ensure healthy growth and prevent bleaching. However, be sure to follow the manufacturer’s recommendations and do not exceed the specified dosages.
3. Take care of proper filtration and water quality.
Regular water changes and proper filtration are key to keeping corals clean and healthy. At least once a week, it is a good idea to check the proper operation of our aquarium equipment to avoid problems caused by faulty equipment.
4. Use appropriate light sources.
Provide the corals with adequate lighting, but avoid overexposure. It is not enough to mount a powerful lamp above the aquarium. The light parameters should be adjusted according to our cast. Although lighting is extremely important yes not always more light = better growth.
5. Ensure adequate water circulation
Adequate water flow allows the delivery of nutrients and prevents sedimentation.
Sum up
Understanding the causes of coral bleaching in marine aquariums is crucial to their health and longevity. Regular maintenance and monitoring of aquarium conditions can help keep corals healthy and prevent bleaching. Remember, healthy corals are a guarantee of a striking and aquarist-satisfying aquarium appearance.