Saving Seafood

Low oxygen levels along Pacific Northwest coast a ‘silent’ climate change crisis

September 29, 2021 — Nearly two decades ago, fishers discovered an odd occurrence off the coast of Oregon. They were pulling up pots of dead or lethargic crabs.

At first they suspected a chemical spill or a red tide. But instead, they learned, dangerously low levels of dissolved oxygen in the ocean water were to blame.

The crabs had suffocated.

These swaths of hypoxic areas have surfaced every summer on Pacific Northwest shores since it was first recorded in 2002. They are spurred by naturally occurring coastal upwellings and algae blooms, exacerbated by climate change, said Francis Chan, director of the Cooperative Institute for Marine Resources Studies at Oregon State University.

Akin to fire season, hypoxia season arrived earlier this year – the earliest start in 20 years, according to Chan. But unlike wildfire, or other visible climate emergencies, it’s gone largely unrecognized.

“It’s kind of a silent problem happening out there,” said Chan. “This year, I can look out and see trees with one side burnt because of the heat wave. As I’m driving on McKenzie highway, I can see Mount Jefferson has no snow on it. But when you drive out to the ocean, it looks exactly the same as last summer.”

Read the full story at the Spokesman-Review

 

Low oxygen is pushing fish into shallower water

September 21, 2021 — Fish can drown. They require oxygen to breathe, and use the oxygen dissolved in water rather than that in the air. When there’s too little oxygen in the water, they have to move or suffer ill effects.

Unfortunately, oxygen concentrations are dropping throughout the oceans. The new research, published in Global Change Biology, spans 15 years of surveys and measurements. The authors stress the importance of accounting for the findings in fishery management and conservation, or risk implementing strategies wildly out of step with conditions under the waves.

“This study finds that oxygen is declining at all the depths we surveyed: from 50 meters (164 feet) to 350 meters (1,148 feet),” says lead author Erin Meyer-Gutbrod, “and so fish seem to be moving up to shallower regions to get to an area where the oxygen is relatively higher.” Now an assistant professor at the University of South Carolina, Meyer-Gutbrod started this analysis as a postdoctoral scholar at the University of California, Santa Barbara.

Oxygen concentrations are decreasing for a number of reasons, including changes in ecology, seasons, and storms. But perhaps the most significant reason is that warmer water holds less dissolved oxygen.

Read the full story at Futurity

 

Lower oxygen level in oceans could be more prominent by 2030s

April 29, 2016 — Reduction in the amount of oxygen present in oceans is already evident in some parts of the world. But as per a new study, the loss of ocean oxygen would be more prevalent in larger sections of oceans between 2030 and 2040. Currently, climate experts can’t say for sure if the fluctuation in the oxygen level is due to natural causes or it is due to climate change.

Decline in ocean oxygen will leave fish, crabs, squid, sea stars and other marine life to face struggle in breathing. Matthew Long from National Centre for Atmospheric Research (NCAR) was of the view that loss oxygen in the ocean has been considered as one of the serious side effects of warming atmosphere.

Professor Long mentioned, “Since oxygen concentrations in the ocean naturally vary depending on variations in winds and temperature at the surface, it has been challenging to attribute any de-oxygenation to climate change”.

Scientists have explained that warming surface waters absorb less oxygen. The oxygen that is absorbed faces more trouble in travelling deeper into the ocean. The researchers have used the NCAR-based Community Earth System Model in order to study the impact of climate change.

Read the full story at Maine News Online