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Feast or famine: Scientists discover how whales adapt their diet to climate change

The researchers studied the biochemical makeup of whales' baleen to discover how their diet changed in response to climate change.

(CN) — A group of researchers has discovered how whales adapt their diet to climate change through the study of the biochemical structure of baleen plates, used by whales to feed.

Scientists from the University of New South Wales Sydney in Australia published their findings Monday in the journal Frontiers in Marine Science. Behemoths of the sea, whales use baleen to filter-feed. These baleen maintain a chemical record of how whales feed, allowing researchers to better understand how these giants respond to climate changes that affect their food supply.

The research team was able to track feeding patterns back nearly 60 years by analyzing the biochemical makeup of the baleen plates.

“What is incredible is that all of this information about dietary and spatial patterns has been unlocked just through analyzing plates in their mouths,” said Adelaide Dedden, lead author and PhD candidate at UNSW Science.

The scientists examined the information contained in the baleen of right and humpback whales in the Pacific and Indian oceans and compared that to changing climate conditions.

“We found that the same conditions – the La Niña events – that bring us these devastating floods are also not good for the humpbacks that migrate along the east coast of Australia,” said UNSW professor Tracey Rogers.

The researchers discovered humpback whales that traveled the east coast of Australia demonstrated poorer feeding habits during La Niña events, when sea surface temperatures will be lower than normal. 

“Baleen whales are enormous and need huge amounts of food. This makes them vulnerable to changes in the environment, but this is also compounded by their survival strategy,” Rogers said. “They fast for the long periods when they leave their productive feeding grounds to breed. That’s why they’re extremely susceptible to changes in ocean-atmospheric cycles as they can drive food availability.”

Rogers said the baleen plates contain stable isotopes, which were analyzed to determine the feeding habits of the whales.

“As the baleen grows, biochemical signals from their food are trapped. Like the information on the pages in a book, they don’t change with time,” said Rogers. “These signals allow us to reconstruct the behavior of the whales through time – what they ate, and the general area they were at the time.”

The researchers explained that humpbacks travel to southern Antarctic waters in the summer to feed on Antarctic krill. The krill rely on sea ice, which is often found in less concentrations during La Niña phases. This in turn leads to less krill for whales to feed on.

“[With] humpbacks from the east coast of Australia showing signs of reduced feeding following La Niña periods, it means they’re potentially struggling to build up the energy reserves required during summer,” Dedden said.

Rogers said previous research shows a link between whale strandings, or beachings, and the years following a La Niña event.

“Our colleagues have shown humpbacks are leaner – a sign they’re experiencing poor feeding conditions – and have a higher chance of stranding in the years following La Niña events,” Rogers said. “With La Niña events predicted to increase in intensity and frequency, it unfortunately means these whales may continue to have more of these poorer feeding prospects, and we could see more strandings in the future.”

She said more needs to be done to address climate change.

“Acting on climate change now is good for whales but also for all of us.”

Categories / Environment, Science

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