Temperature blob in Pacific Ocean gives a glimpse of climate impact on humpback whales

March 20, 2019 by Bob Yirka, Phys.org report

A team of researchers with the Keiki Kohola Project and California State University reports that a recent "blob" of warm water in the Pacific gives marine scientists a preview of the impact of climate change on humpback whales. In their paper published in the journal Royal Society Open Science, the group describes their study of the whales and what they found.

Humpback whales were once hunted to the point that they became endangered, but several decades ago, international laws were enacted to protect them, and they rebounded—these measures were so successful that the U.S. National Marine Fisheries Service took the whales off the endangered species list back in 2016. But now, it appears the whales face a new threat—climate change.

In a new effort, the researchers studied the reproductive habits of humpback whales that migrate between the waters off the Alaskan coast and those that surround the Hawaiian Islands. They had noted that in 2013, a giant mass or "blob" of warm water had formed in the Gulf of Alaska, and over the course of the next six years, slowly made its way south. Prior research had shown that temperatures in the blob were up to 3 degrees C warmer than surrounding water—high enough to kill krill and other sea creatures that serve as food for humpback whales. This led the researchers to embark on a study of the impact of the blob on the humpback whales.

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Plankton Adjusts to Changing Ocean Temperatures

Mar. 8, 2013 — Imagine trying to swim through a pool of honey. Because of their small size, this is what swimming in water is like for tiny marine plankton. So, it was often assumed they would be easy prey, especially in the dense viscosity of colder waters, but that is not necessarily so.

Texas Tech Associate Professor and Whitacre Endowed Chair in Mechanical Engineering Jian Sheng, along with biologists Brad Gemmell and Edward Buskey from the University of Texas Marine Science Institute, have discovered new information that explains how these tiny organisms overcome this disadvantage.

Their paper, titled "A compensatory escape mechanism at low Reynolds number" was published in the current issue of Proceedings of the National Academy of Sciences.

"The purpose of the study was in trying to determine the effects of climate change at the very base of the food chain," Sheng said.

As one of the most abundant animal groups on the planet, many species, including many commercially important fish species, rely on planktonic copepod nauplii at some point during their life cycle. Understanding the ability of these animals to respond to changes in the environment could have direct implications into understanding the future health of our oceans.

By independently varying temperature and viscosity, Sheng recorded their movements with 3-D high speed holographic techniques developed by the Sheng lab at Texas Tech.

"At 3,000 frames per second, it was like tracking a racecar through a microscope," Sheng said. "We were able to determine that the plankton adapted to changes in viscosity by altering the rhythm of its pulsing appendage."

The response, built-in to its natural muscle fiber, was only triggered by changes in temperature, Sheng said. It could not compensate for changes in viscosity due to environmental pollution, such as algae blooms or oil spills.

http://www.sciencedaily.com/releases/2013/03/1303081

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