Ocean Heat Waves Are Threatening Marine Life

New York Times, March 4th 2019 –
By Kendra Pierre-Louis and Nadja Popovich

When deadly heat waves hit on land, we hear about them. But the oceans can have heat waves, too. They are now happening far more frequently than they did last century and are harming marine life, according to a new study.


The average number of marine heat wave days for the period 1987-2016, compared to the average for 1925-1954. Orange-red range indicates 18-36+ more marine heat wave days compared to the mid-20th century.
Source: Nature Climate Change | By The New York Times

The study, published Monday in the journal Nature Climate Change, looked at the impact of marine heat waves on the diversity of life in the ocean. From coral reefs to kelp forests to sea grass beds, researchers found that these heat waves were destroying the framework of many ocean ecosystems.

Marine heat waves are said to occur when sea temperatures are much warmer than normal for at least five consecutive days.

Scientists estimate that the oceans have absorbed more than 90 percent of the heat trapped by excess greenhouse gases since midcentury. Humans have added these gases to the atmosphere largely by burning fossil fuels, like coal and natural gas, for energy.


An estimated one billion people depend on coral reefs, which are highly sensitive to temperature, for food or income. Credit Gabriel Barathieu/Biosphoto/Minden Pictures

Bleached coral in Kaneohe Bay off Oahu, Hawaii. Credit Caleb Jones/AP

An earlier study by some of the same researchers found that, from 1925 to 2016, marine heat waves became, on average, 34 percent more frequent and 17 percent longer. Over all, there were 54 percent more days per year with marine heat waves globally.

The most severe years tended to be El Niño years. Warmer ocean temperatures are one of the characteristics of an El Niño pattern.

“There’s also some indication that El Niños have been getting more extreme with climate change,” said Eric C. J. Oliver, an assistant professor of physical oceanography at Dalhousie University in Halifax, Nova Scotia, who was a co-author of the study. But regional marine heat waves can happen even without an El Niño, he said.

Read more about ocean heat waves

Sea Change: Pacific Ocean Takes Perilous Turn

By Craig Welch, The Seattle Times

Ocean acidification, the lesser-known twin of climate change, threatens to scramble marine life on a scale almost too big to fathom.

NORMANBY ISLAND, Papua New Guinea — Katharina Fabricius plunged from a dive boat into the Pacific Ocean of tomorrow.

She kicked through blue water until she spotted a ceramic tile attached to the bottom of a reef.

A year earlier, the ecologist from the Australian Institute of Marine Science had placed this small square near a fissure in the sea floor where gas bubbles up from the earth. She hoped the next generation of baby corals would settle on it and take root.

Fabricius yanked a knife from her ankle holster, unscrewed the plate and pulled it close. Even underwater the problem was clear. Tiles from healthy reefs nearby were covered with budding coral colonies in starbursts of red, yellow, pink and blue. This plate was coated with a filthy film of algae and fringed with hairy sprigs of seaweed.

Instead of a brilliant new coral reef, what sprouted here resembled a slimy lake bottom.

Isolating the cause was easy. Only one thing separated this spot from the lush tropical reefs a few hundred yards away.

Carbon dioxide.

Read More Here

Nervous Nemo: Ocean Acidification Could Make Fish Anxious

By Douglas Maine, December 6th, 2013  Livescience.com

Ocean acidification threatens to make fish, like this juvenile rockfish, more anxious.

Ocean acidification threatens to make fish, like this juvenile rockfish, more anxious.
Credit: Scripps Institution of Oceanography

Ocean acidification, which is caused by rising levels of carbon dioxide in the atmosphere being absorbed into the sea, has made many worry because of the problems it will likely create, such as a decline in shellfish and coral reefs. But humans may not be alone in their anxiety: Ocean acidification threatens to make fish more anxious as well (and not because they are reading about ocean acidification on LiveScience.com. At least so far as we know.)

A new study found that after being placed for a week in an aquarium with acidic seawater — as acidic as the oceans are expected to be on average in a century’s time — juvenile rockfish spent more time in a darkened corner, a hallmark of fish anxiety, and the same behavior exhibited by fish given an anxiety-inducing drug.

“They behaved the same way as fish made anxious with a chemical,” said Martin Tresguerres, a marine biologist at the Scripps Institution of Oceanography at the University of California, San Diego.

Read More Here