成人大片

鈥淲e found several proteins important for vision that were affected by thermal stress,鈥� says Dr Qiaz Hua, a recent PhD graduate from the 成人大片鈥檚 School of Biological Sciences.

鈥淥ne 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.

鈥淭he 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.鈥�

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

鈥淭he 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,鈥� says Dr Hua.

鈥淗aving impaired vision will affect an octopus鈥檚 chances of survival in the wild through increased predator risk as well as lower foraging success.鈥�

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鈥檚 aquatic sciences division, exposed Octopus berrima embryos to different temperature treatments, a control 19掳C exposure, 22掳C to model current summer temperatures, and 25掳C to model projected summer temperatures.

鈥淭he future-projected temperature was based on the Intergovernmental Panel on Climate Change鈥檚 projected increase of about 3掳C of warming by 2100,鈥� Dr Hua says.

In addition to impaired vision, Dr Hua's study, , found increased ocean water temperatures would have a negative effect on octopus broods.

鈥淲e 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,鈥� Dr Hua says.

鈥�In the broods where none of the eggs hatched, the mothers died naturally while the eggs were still in early development stages.

鈥淏ecause maternal care of embryos occurs in octopuses, global warming could have a simultaneous impact on multiple generations, with the low survival rate of the embryos caused by the direct effect of thermal stress as well as the indirect effect of thermal stress on the mothers.

鈥淥ur study shows that even for a highly adaptable taxon like octopuses, they may not be able to survive future ocean changes.鈥�

Other effects of higher temperatures which have been observed in octopuses include a higher metabolic rate, reduced size at maturity, and even a range shift in the distribution of some species.

鈥淲e hope that future research would examine a combination of environmental stressors including ocean acidification, warming, and deoxygenation,鈥� Dr Hua says.

鈥淚t would also be useful to do a transgenerational experiment to see if sensitivity or tolerance to the environmental stressors is passed down from one generation to the next, which help us understand the impacts on the continuation of the species.鈥�