Table corals on the Great Barrier Reef provide vital sun shelter for large fish and need greater protection, scientists say.
Researchers have found the loss of the vulnerable corals cause the fish dependent on them for sun protection to leave the ecosystem.
They say this is concerning given the table corals are susceptible to the pressures facing the reef including ocean acidification, bleaching and crown-of-thorns starfish outbreaks.
Recently published James Cook University studies have shown large fish leave ecosystems if the corals aren't there to provide shelter from the searing sun.
In the studies, fish were denied access to table coral off Lizard Island and their movements monitored for months.
"We found the drop off in species happened almost immediately," said lead study author and PHD student James Kerry.
"The loss of table corals denies fishes important habitat, which they use to shelter from the sun."
Previous studies have shown some fish can suffer sun lesions, including melanoma.
Mr Kerry said about 40 species used the table corals including coral trout, snapper, red emperor and sweetlips.
These fish were predators that helped control populations of smaller fish and ultimately helped maintain balanced coral reef ecosystems, he said.
Scientists at JCU's ARC Centre of Excellence for Coral Reef Studies want to see more done to improve the health of the Great Barrier Reef to reduce the multiple threats facing the vulnerable corals.
The call comes days ahead of UNESCO's decision on whether to endorse a draft ruling to keep the reef off its "in-danger" list.
