Blinding Nemo: Young clownfish that live closest to the bank die FASTER than those further out because they are exposed to artificial lighting, warns the study
- Clownfish, the closest to the coast, die faster than those farther out, a study warns
- This is due to exposure to artificial light from street lights, piers and harbors
- The reef dwellers feed themselves during the day and need a period of inactivity at night to recharge
- But when this is interrupted, it leads to higher mortality and a slower growth rate
Young clownfish, those closest to the coast, die faster than those further out from exposure to artificial lighting from street lights, piers and harbors, warns a new study.
Made famous by ‘Finding Nemo’, the iconic reef inhabitants feed, reproduce, defend their territories and interact with other fish during the day before they sleep at night.
As with humans, this period of inactivity is critical to their wellbeing as they need it to recharge, researchers said.
But when downtime is interrupted by artificial light, the effect on clownfish can be disastrous.
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Sleep-needy: Young clownfish that live near the coast die faster than those further out because they are exposed to artificial lighting from piers and harbors, a study warns
Clownfish have been monitored in the reefs around Moorea in French Polynesia for almost two years
Why do clownfish need moonlight rather than artificial light to thrive?
Clownfish survival and growth rates are negatively affected by long-term nocturnal exposure to artificial light, a study found.
This could be due to the light’s potential to attract natural predators, as well as its harmful effects on the physiology of fish, the international research team said.
Clownfish need a period of inactivity at night to recharge, but the lack of sleep caused by artificial light can also lead to an increased metabolism with higher energy demands.
This could be one of the reasons young clownfish stunted growth.
In comparison, those who lived farther from shore and enjoyed natural moonlight had higher survival rates and increased growth.
A team of international scientists from France, Great Britain, Chile and Australia found that young clownfish had a higher death rate when exposed to light pollution near the coast.
This is due to the deleterious effects it has on fish physiology, as well as the possibility of artificial light attracting natural predators.
The young clownfish also grew 44 percent slower than those under natural light.
“The light pollution effects identified here are likely to be underestimated and urgent mitigation and policy changes are needed,” said Stephen Swearer, marine ecology expert.
The clownfish have been in the for nearly two years Reefs around Moorea in French Polynesia.
Professor Swearer of the University of Melbourne said the researchers exposed 42 clownfish in their host anemones to either artificial light (ALAN) or natural light in the lagoon at night.
“36 percent of clownfish that were exposed to light pollution were more likely to die than fish under natural light cycles,” said lead author Jules Schligler of the École Pratique des Hautes tudes PSL Université Paris.
He said clownfish can be found in shallow coastal waters and are easily affected by light from street lamps, piers or harbors at night as they are very sedentary in anemones.
In the research, the scientists said that “even the surviving fish did not completely escape the effects of artificial light at night because they grew less than the fish in the control group.”
Reef dwellers: Researchers exposed 42 clownfish to either artificial light or natural moonlight
The University of Melbourne study created this graph to summarize their findings
“This is the first time the effects of ALAN have been tested on a coral reef fish in the wild and for such a long period of time,” said Daphne Cortese, postdoctoral fellow at the University of Glasgow.
“With 12 percent of all coral fish living in close association with other sedentary species such as corals and anemones, light pollution could already have a serious negative impact on a fifth of reef fish populations.”
Scientists hope the research will help raise awareness of the effects of ALAN on coastal marine ecosystems.
“Many marine reserves are affected by light pollution at night and the authorities do not take this pollution into account,” said Ricardo Beldade, associate professor at the Pontificia Universidad Católica de Chile.
“We hope that policy makers will take this threat to future management strategies much more seriously.”
The study is published by the University of Melbourne in the journal Proceedings of the Royal Society B.
CLOWNFISH FATHERS HAVE A STRONG USEFUL INTINCT DUE TO A “LOVE HORMONE”
Care: The parenting instinct of the clownfish is so strong that even if you place eggs from an unrelated nest near a bachelor anemonefish, it will take care of them
One area where Finding Nemo was right is the great effort that clownfish fathers go to to support their offspring, just like marlin.
Your parenting instincts are so strong that even if you place clownfish eggs from an unrelated nest near a bachelor anemonefish, they will take care of them.
Researchers previously found the love hormone behind this reproductive behavior.
And it’s very similar to oxytocin, the hormone that facilitates the bond between human mothers and their babies after birth.
Scientists at the University of Illinois at Urbana-Champaign decided to investigate the brain chemistry behind this parental care.
So they took individual anemonefish that fathered and gave them an injection of antagonists.
They then analyzed how these drugs could either promote or inhibit male parental care.
They found that anemonefish rely on isotocin, a signaling molecule that is almost identical to oxytocin.
When the researchers blocked this hormone, they found that the anemonefish fathers stopped looking after their eggs.