Ocean heatwaves displace wildlife

Bryde’s Whale | Image: NOAA

Marine heatwaves can shift suitable habitat for whales, sea turtles and other wildlife by thousands of miles, research suggests.

Unusually hot sea temperatures are known to adversely effect species that can’t move, such as corals which die-off in highly-visible bleaching events. Many ocean creatures can up and relocate to their preferred conditions, however.

Scientists at the National Oceanic and Atmospheric Administration (NOAA) measured the shifts in sea temperature that cause species to move. The resulting study suggests that marine life might have to move considerable distances to find more suitable sea temperatures, ranging from tens to thousands of miles.

Image: Ralph Olazo | Unsplash

This could spell major impacts for wildlife and natural systems, as well as for human activities such as fishing.

When the environment changes, many species move. This research helps us understand and measure the degree of change they may be responding to

Michael Jacox, research scientist NOAA Fisheries’ Southwest Fisheries Science Centre

Marine heatwaves are usually caused by weather, either more heat than usual goes into the ocean than usual or the weather suppress the amount of heat coming out.

From 2014 to 2016 waters off the West Coast of America was hit with a marine heat wave that came to be known as The Blob. This stretch of warm water had big impacts on the marine environment and West Coast economy.

This image from September compares sea surface temperature anomalies (how much warmer or cooler the water is compared to normal levels) for September 2014, when the Blob emerged, and September 2019. Image: NOAA Fisheries

Marine heatwaves can have impacts on a range of species, for example a heatwave in the Pacific in 2014-215 shifted surface temperatures more than 400 miles along the west coast of the US. This pushed the prey of California sea lions further from their breeding rookeries and left hundreds of starving pups to strand on beaches.

In 2012 in the north-west Atlantic, a heatwave pushed commercial seafood species such as squid and flounder hundreds of miles north and contributed to a lobster boom.

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