Octo-ometry: global warming severe affect on octopus’ sight

Warming ocean temperatures caused by climate change could have a direct effect on octopus’ sight according to new research from South Australia and California.

Marine biologist Dr Qiaz Hua and a team at The University of Adelaide Environment Institute and University of California Davis, tested embryos of the Southern Keeled Octopus (Octopus berrima) in water of different temperatures and discovered the potential threat that increasing ocean temperatures pose.

The researchers exposed the embryos to water at 19°C (the control), 22°C (The current summer average temperatures) and 25°C (the future projected ocean temperature).

In a paper published in Global Change Biology the team says it found “that future projected temperatures significantly reduced levels of key eye proteins… suggesting the embryonic octopuses had impaired vision at elevated temperature. We also found that this was coupled with a cellular stress response.

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A newly hatched Octopus berrima (~1cm) beside remnants of an egg casing (Qiaz Hua)

“Energy resources were also redirected away from non-essential processes such as growth and digestion.”

More than 95% of all embryos raised under control and current temperature treatments hatched.

But in two out of three broods raised under “future temperatures” none of the embryos hatched.

The two brooding females at 25°C died naturally while their eggs were in the early stages of development, and the remaining female showed visible signs of stress (e.g., remained out of den, abnormal body posture and morphology) and was euthanised shortly after her first eggs hatched.

In contrast, all six brooding females acclimatized to 19 and 22°C did not exhibit any signs of stress.

The team noted that “the study was not a direct reproduction of what would happen with global warming.”

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Egg casing with unhatched octopus (Qiaz Hua)

Hua told Cosmos the octopuses were exposed to a much more rapid increase in water temperatures than is expected to occur because of climate change, which will occur over decades: “… so we think there is a potential for adaptation across generations, but this would be difficult to tell without further research.”

The octopus adapts quickly to its environment because of its short lifespan—between 1 to 3 years.

Hua says now that we know what severe detrimental effects thermal stress can have on octopuses, raising awareness on the consequences of climate change and doing our part as individuals should be a top priority.

Octopus mother in its makeshift homemade of PVC pipe (Qiaz Hua)


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