Clownfish are a favorite reef fish for many. For those of us who were brought up watching Finding Nemo films to nature enthusiasts who are amazed by their colors and their symbiotic relationship with anemones, clownfish have a special place in many of our hearts. 

Because of the wonders of these fish, it is sad to find out that they are being significantly harmed by climate change. In a recent study, scientists have discovered the physiological changes that the clownfish are facing under the pressure of warming oceans. 

What Are Clownfish and Why Are They So Important?

The false clownfish, also known as the clown anemonefish, are small, bright orange fish. They are easily identified by their three white bars that break up their orange. They are found in coral reefs in the Indian Ocean, the Western Pacific Ocean, and the Red Sea. According to National Geographic, there are 30 different species of clownfish. 

They are really amazing creatures and are famous for their symbiotic relationship with anemones. They seek refuge and protection within the anemone, however, anemones have stinging tentacles. The clownfish get around this by gently touching the tentacles slowly. As the clownfish touch the anemone with different parts of their bodies, they develop a mucus on their skin that makes them immune to the poison of the anemones. 

After becoming immune to the anemones, they get protection from them and in return, the clownfish ward off any predators and will keep the anemones clean. This means that both of the creatures live healthy and happy lives. 

This symbiotic relationship is important to understand when it comes to how climate change is affecting the clownfish. Because they use the anemones for a home, when the anemones are affected, the clownfish are too. 

How Is Climate Change Affecting Clownfish?

A recent study by scientists at the University of Glasgow looked into how bleached coral reefs affect the health of clownfish.

Coral reef bleaching is caused by changes that stress out the corals, such as warmer waters or pollution. According to a study by the Intergovernmental Panel on Climate Change, the ocean has absorbed 93% of the excess heat from greenhouse gasses since the 1970s. This makes the temperature of the ocean rise, causing coral reefs to bleach. 

Anemones also suffer from bleaching. According to National Geographic, the process of anemone bleaching is nearly identical to the process of coral bleaching. The algae that live in anemones tissue will be expelled and the anemones will appear white. However, anemones are more likely to survive bleaching than corals as they get most of their nutrients from plankton and small fish, and not the algae that live in their tissue.  

According to a scientific report in Nature, the symbiotic relationship that anemones have with clownfish might actually help them recover from bleaching. The nutritional benefits that anemones get from clownfish increase their algal symbiont density. This was proven in a study, where bleached and unbleached anemones were looked at, some with clownfish and some not. They found that after 106 days, the bleached anemone that was hosting a clownfish was fully recovered. Their algal symbiont density and colors were similar to the control anemones that were not bleached. However, the anemones that were not hosting a clownfish did not recover, with 78% fewer algal symbionts than the non-bleached control anemones. 

This is really exciting, and it really highlights the wonders of nature and how different creatures help each other to survive. However, new research has found that, even though clownfish help anemones recover from bleaching, the bleaching of the anemones can really affect the health of the fish. 

The research conducted by the University of Glasgow and CRIOBE was undertaken in French Polynesia and, according to the Universities website, found that anemone bleaching can affect the growth and wellbeing of the clownfish that they host. For their study, the team exposed 47 juvenile clownfish to bleached anemones and non-bleached anemones for several months. The researchers measured the growth, behavior, and metabolism of the clownfish. 

They found that the clownfish that lived in bleached anemones had a lower growth rate and were less active than the clownfish in healthy anemones. They also appeared to leave their host anemone more. Because of their slower metabolism and lower growth rate, the life-long health of the clownfish is at risk. The anemones might recover from the bleaching, but the fish will not. 

What Does This Mean for Coral Reefs?

This study is one that focuses on the secondhand effects of coral reef bleaching. It shows us that the corals and the anemones that suffer from bleaching are not the only species that are at risk from the phenomenon. The marine life that relies on the coral reefs is also significantly affected. 

This is something that conservationists and scientists have known for a while. Of course, if an animal’s habitat dies they will obviously suffer. However, what is interesting about this study is that it shows that even if the habitat recovers, there are still long-term consequences of bleaching. 

Hopefully, this study will raise awareness of the importance of protecting anemones as well as corals. They are just as important, and even though they appear to survive bleaching better than the majority of corals, the ecosystem will never fully recover. This means that so many wonderful marine life is at risk. 

What Can We Do?

We need to raise awareness of the importance of coral reefs and what bleaching does to the fish and invertebrates that we know and love. When anemones are bleached, clownfish suffer. We do not know the true extent of this suffering, too, and these fish may become a victim of global warming because of their symbiotic relationship with anemones.

We hope that there will be more studies soon that will help us understand the true effects of coral and anemone bleaching on the inhabitants of coral reefs. With this knowledge, we can work on protecting and maintaining the wonderful ecosystems around the world.