Heat stress from ocean warming harms octopus vision

While climate change has led to an increase in the abundance of octopuses, heat stress from projected ocean warming could impair their vision and impact the survivability of the species.

“We found several proteins important for vision that were affected by thermal stress,” says Dr Qiaz Hua, a recent PhD graduate from the University of Adelaide’s School of Biological Sciences.

“One of them is a structural protein found in high abundance in animal eye lenses to preserve lens transparency and optical clarity, and another is responsible for the regeneration of visual pigments in the photoreceptors of the eyes.

“The levels of both of these proteins were significantly reduced under projected ocean warming conditions, which suggests that octopus vision is likely to be impaired under thermal stress.”

Octopuses are highly visual animals, with 70 per cent of the octopus brain dedicated to vision – which is 20 per cent more than in humans.

“The primary functions of vision include but are not limited to visual acuity, discrimination of brightness, depth perception, motion detection and polarisation, and it is crucial for detecting predator and prey as well as for communication,” says Dr Hua.

“Having impaired vision will affect an octopus’s chances of survival in the wild through increased predator risk as well as lower foraging success.”

To make this finding, the research team, including academics from the University of South Australia, University of California Davis, and the South Australian Research and Development Institute’s aquatic sciences division, exposed Octopus berrima embryos to different temperature treatments, a control 19°C exposure, 22°C to model current summer temperatures, and 25°C to model projected summer temperatures.

“The future-projected temperature was based on the Intergovernmental Panel on Climate Change’s projected increase of about 3°C of warming by 2100,” Dr Hua says.