CANBERRA, April 5 (Xinhua) -- Heat stress from rising ocean temperatures could impair the vision of octopuses and threaten the survivability of the species, Australian research has warned.
In a study published on Friday, international research led by the University of Adelaide discovered proteins that are important for octopus vision are affected by thermal stress.
They found that the levels of two proteins, one which preserves lens transparency and optical clarity and another that is responsible for the regeneration of visual pigments in the eye's photoreceptors, were reduced significantly under projected ocean warming conditions, suggesting impaired vision.
Approximately 70 percent of an octopus brain is devoted to vision, 20 percent more than in humans.
Qiaz Hua, lead author of the study, said octopuses use their vision for depth perception, motion detection, communication and to detect predators and prey.
"Having impaired vision will affect an octopus's chances of survival in the wild through increased predator risk as well as lower foraging success," she said in a media release.
To make their findings the research team exposed the embryos of southern keeled octopus, also known as the octopus berrima, to water temperatures of 19, 22 and 25 degrees Celsius to simulate current summer ocean temperatures and projected summer temperatures in the year 2100.
In addition to impairing vision, they found rising temperatures would also negatively impact octopus broods.
"We found a high mortality rate under future warming conditions. Out of three replicate octopus broods, none of the eggs hatched for two of them and less than half of the eggs hatched for the remaining brood," Hua said.
"Our study shows that even for a highly adaptable taxon like octopuses, they may not be able to survive future ocean changes," she said. ■
