Earth & Space
Published

Here's why scientists are worried about newly discovered underwater heat waves

Called bottom marine heat waves, these temperature anomalies are linked to declining fish populations, the spread of invasive species and millions of tourism dollars lost.

By Angeli Gabriel Source FOX Weather

NOAA scientists are studying Alaska's marine ecosystems

The EcoFOCI program helps determine impacts on Alaska's ecosystems from a changing climate. (NOAA)

In a recent study, researchers discovered extreme warming along the seafloor of the North American continental shelves.

Continental shelves form the edge of the continent. They extend up to 300 miles out to sea and, compared to the majority of the ocean floor, have shallow water. Their shallow depths and relative proximity to land allow continental shelf waters to be productive.

For example, the bottom of continental shelves serves as critical habitats for commercial species such as lobsters, scallops, crabs, flounder, cod and other groundfish, according to the National Oceanic and Atmospheric Association (NOAA).

Ling cod, like this one caught off of Humboldt Bay Jetty in California, are a member of Pacific groundfish communities vulnerable to impacts from bottom marine heat waves. (Nicholas Easterbrook / NOAA Fisheries / FOX Weather)

CRABBING INDUSTRY LOSES FIGHT TO PREVENT FISHING IN CRITICAL ALASKAN ECOSYSTEM

These habitats, however, can become compromised when waters close to the seafloor experience heat waves, according to a paper published by researchers from NOAA, the National Center for Atmospheric Research (NCAR) and the Cooperative Institute for Research in Environmental Sciences (CIRES).

Called bottom marine heat waves, these temperature anomalies can occur with little or no evidence of warming at the surface.

This can have important implications for commercial fisheries, which may not realize the occurrence of the heat wave until the impacts start to show, said lead author Dillon Amaya, a research scientist with NOAA’s Physical Science Laboratory.

Image 1 of 7

Graphic depicting satellite captured, bathymetric data of the western Atlantic Ocean Basin and its ocean floor features. The areas highlighted in light teal are part of the continental shelf of North America. (NOAA's National Environmental Satellite and Information Service)

Image 2 of 7

Here are 2 of 9 illustrations showing the average intensity of bottom heat waves ( heat anomalies) that occurred between 1993 and 2019 in each of the large marine ecosystems studied by a team of NOAA scientists.  (NOAA Physical Sciences Laboratory)

Image 3 of 7

Here are 2 of 9 illustrations showing the average intensity of bottom heat waves ( heat anomalies) that occurred between 1993 and 2019 in each of the large marine ecosystems studied by a team of NOAA scientists.  (NOAA Physical Sciences Laboratory)

Image 4 of 7

Here are 2 of 9 illustrations showing the average intensity of bottom heat waves ( heat anomalies) that occurred between 1993 and 2019 in each of the large marine ecosystems studied by a team of NOAA scientists.  (NOAA Physical Sciences Laboratory)

Image 5 of 7

Here are 2 of 9 illustrations showing the average intensity of bottom heat waves ( heat anomalies) that occurred between 1993 and 2019 in each of the large marine ecosystems studied by a team of NOAA scientists.  (NOAA Physical Sciences Laboratory)

Image 6 of 7

Here are 2 of 9 illustrations showing the average intensity of bottom heat waves ( heat anomalies) that occurred between 1993 and 2019 in each of the large marine ecosystems studied by a team of NOAA scientists.  (NOAA Physical Sciences Laboratory)

Image 7 of 7

This graphic shows several ocean floor features on a scale from 0-35,000 feet below sea level. The following features are shown at example depths to scale, though each feature has a considerable range at which it may occur: continental shelf (300 feet), continental slope (300-10,000 feet), abyssal plain (>10,000 feet), abyssal hill (3,000 feet up from the abyssal plain), seamount (6,000 feet up from the abyssal plain), ocean trench (36,000 feet), and volcanic island (above sea level).  (NOAA Office of Education)

HOW TO WATCH FOX WEATHER

One such impact was found in 2021 after a multi-year marine heat wave known as "The Blob" swept through the northern Pacific Ocean. 

According to NOAA, the Blob included masses of water between 4 and 10 degrees Fahrenheit above average that disrupted West Coast marine ecosystems, depressed salmon returns, and caused millions of dollars in damages to commercial fisheries.

Bottom marine heat waves have also been linked to the expansion of invasive lionfish, a tropical fish species that prey on native species along the southeast U.S. coastlines.

A lionfish. (NOAA / NOAA)

NOAA said other impacts caused by unusually warm bottom water temperatures include the disappearance of near-shore lobster populations in southern New England, coral bleaching and declines of reef fish and changes in survival rates of young Atlantic cod.

HOW GLOUCESTER HONORS A FISHING LEGACY SPANNING OVER 400 YEARS

Marine heat waves have become increasingly common. According to NOAA, they have become about 50% more frequent over the past ten years.