Ocean heat waves are threatening marine life, biodiversity
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What are ocean heat waves? They are periods of extreme temperatures. They last five days. Sometimes they last more. They have become more common. This has happened in recent decades. The Earth’s number of annual ocean heat wave days spiked. It spiked by around 54 percent. That was between 1987 and 2016. That's according to a study. It was published in Nature Climate Change. Abnormally high temperatures are occurring more frequently. They also lasting for longer periods of time.
Underwater heat waves pose a big threat to marine ecosystems. That's according Damian Carrington. He explained it for the Guardian. The ecosystems are already at risk. That’s due to several issues. The issues include overfishing. It includes rampant plastic pollution.
Extreme temperatures exact damage on foundational organisms. These include kelp forests. It includes seagrass meadows. And it includes coral reefs. These framework species provide shelter. They provide food. This is for many other ocean creatures. The temperatures sweep through oceans. This is like wildfires that blaze through forests on land. Such destruction will likely have cascading consequences for marine biodiversity. The study’s authors make this warning.
Researchers were led by Daniel Smale. He is an ecologist. He belongs to Great Britain’s Marine Biological Association. He turned to 116 previously published academic studies. He used them to assess the effects of ocean heat waves. The papers yielded data. It came from more than 1,000 ecological records. This enabled the team to hone in on multiple recorded instances of unusually high temperatures.
The scientists identified regions and species deemed most vulnerable to temperature surges. They reflected on eight specific heat waves.
Which areas topped the list? The Pacific Ocean. The Atlantic Ocean. And the Indian Ocean. More places emerged as particular concerns. These included the Caribbean’s coral reefs. It included Australia’s seagrass. And it included California’s kelp forests. That's according to Mary Papenfuss. She was writing for the Huffington Post.
The team notes that stationary plants and animals were the hardest hit. That's according to the Pacific Standard’s Kate Wheeling. Tropical fish and mobile invertebrates were able to cope with the heat. They did so by moving to different habitats.
The researchers actually observed heightened levels of fish diversity. This happened during periods of above-average temperatures. This is likely due to the animals’ mass migration. They went toward friendlier waters. The same trend did not prove true for sea-dwelling birds. Shifting habitats limited the avian creatures’ access to prey. That's according to John Timmer. He was reporting for Ars Technica.
Marine heat waves are triggered by heat from the sun. And by shifting warm currents. That's according to Reuters’ Alister Doyle. Wheeling explained it further. The phenomenon is measured relative to average ocean temperature. Because of that it can occur in any region at any point during the year. El Nin?o is a regularly occurring climate pattern. It makes the waters of the central and eastern Pacific warmer than normal. It appears to exacerbate incidents of extreme heat. But heat waves can (and do) occur without the presence of El Nin?o. That's according to The New York Times’ Kendra Pierre-Louis and Nadja Popovich.
Pierre-Louis and Popovich explain that damage to ocean habitats will also affect humans who rely on fishing and fish farming. But the researchers’ findings are most consequential for marine ecosystems.
“Certainly there’s going to be changes with climate change to marine communities. But still the sun is going to shine. Plankton is going to grow. Things are going to eat that plankton. So it's not like the oceans are going to become the dead sea." That's according to Nick Bond. That's what he told the Pacific Standard. He is a climatologist. He works at the University of Washington. He was not involved in the study.
“It's just that, as a consequence of what we're doing to the oceans, there's going to be different marine communities in different places than what we're used to,” Bond concludes. “Obviously that is a problem. Because we're sort of set up for what the climate is now. This is not what it is going to be in the future."