103 301 319 | Ocean heat waves are killing underwater life, threatening biodiversity, March 4, 2019

https://www.nationalgeographic.com/environment/2019/03/ocean-heat-waves-threaten-sea-life-biodiversity/?fbclid=IwAR0Zuw6t0T31L-9F6-2z_CuGngbiRaS0z_2VStHj7P8gQsUvZ5obh_iX7b0&utm_source=reddit.com
https://archive.is/K6OQO

Intense heat waves are bad for human health. They can lead to sometimes deadly conditions like dehydration and stroke. And just like extreme temperatures on land, marine heat waves can drastically alter life under the sea.

A new study published today in Nature Climate Change found that the occurrences of marine heat waves have substantially grown in the past three decades, and it’s becoming clearer how deadly warmer temperatures are for biodiversity.

Marine heat waves are periods when the average water temperature of a given region is exceptionally high. In the past 30 years marine heat wave days have increased by just over 54 percent, a trend the study’s authors found consistent with declines in oceans life.

High-profile marine heat waves like “the blob,” a huge mass of warm water that was present off the U.S. West Coast from 2014-2016, were included in the study. The blob was responsible for massive die-offs of everything from invertebrates to marine mammals.

“It is clear that extreme warming events can drive abrupt changes in entire ecosystems with widespread consequences,” says study author ecologist Daniel Smale.

Shrinking biodiversity may also one day have profound impacts on food security and sea-based economies. Last week, a study published in the journal Science found that climate change is causing fish to disappear. Global populations of fish taken for human consumption by fisheries have decreased by around 4 percent. For some regions that experience warming waters as well as overfishing, the decline is more than 30 percent.

Smale also worries that the loss of critical regions like coral reefs, seagrass beds, and kelp forests will only add more carbon dioxide to the atmosphere. Scientists estimate the ocean has absorbed 26 percent of the carbon released into the atmosphere in the past decade. All of the carbon that was absorbed by underwater flora is released when the ecosystem dies.

“Ocean systems are facing a number of threats, such as plastic pollution and ocean acidification,” says Smale. “But it is clear that extreme warming events can drive abrupt changes in entire ecosystems with widespread consequences.”

He predicts that warming events will continue to threaten the balance of ocean life in the coming decades.

“The ultimate cause is something we have to address,” says Katie Matthews, the deputy chief scientist at Oceana. “If we don’t do that, everything else we work on will have little to no impact.”

She adds that climate-conscious fishery management and monitoring ocean warming in real time are tools that can help minimize impacts from warming events in the meantime.