Aggressive seaweed smothers one of world’s most remote reefs

  • A new species of seaweed, seen here covering coral on a reef at Pearl and Hermes Atoll in the remote Northwestern Hawaiian Islands, is killing large patches of coral on once-pristine reefs and is rapidly spreading across one of the most remote and protected ocean environments on Earth. (Heather Spalding/College of Charleston via AP)

  • University of Hawaii at Manoa Interim Associate Dean and Professor Alison Sherwood looks at a new species of seaweed found in the Northwestern Hawaiian Islands in late June in her lab in Honolulu. Sherwood, chief scientist on a study that identified the new species, said the aggressive seaweed is overtaking one of the most remote and protected coral reefs in the world. The algae forms huge, thick mats of vegetation that is killing the coral beneath it. (AP Photo/Caleb Jones)

  • A study from the University of Hawaii and others says the seaweed is spreading more rapidly than anything they've seen in the Northwestern Hawaiian Islands, a nature reserve that stretches more than 1,300 miles north of the main Hawaiian Islands. The algae easily breaks off and rolls across the ocean floor like tumbleweed, scientists say, covering nearby reefs in thick vegetation that out-competes coral for space, sunlight and nutrients. (Heather Spalding/College of Charleston via AP)

  • A new species of seaweed covers dead a coral reef at Pearl and Hermes Atoll in the remote Northwestern Hawaiian Islands in this August 2019 photo. Researchers say the recently discovered species of seaweed is killing large patches of coral on once-pristine reefs and is rapidly spreading across one of the most remote and protected ocean environments on Earth. Below, a diver holds a mat of the seaweed. (Photos by Taylor Williams/College of Charleston via AP)

  • In this July 31, 2019 photo provided by researcher Heather Spalding, a new species of seaweed covers dead coral on a reef at Pearl and Hermes Atoll in the remote Northwestern Hawaiian Islands. Researchers say the recently discovered species of seaweed is killing large patches of coral on once-pristine reefs and is rapidly spreading across one of the most remote and protected ocean environments on earth. A study from the University of Hawaii and others says the seaweed is spreading more rapidly than anything they’ve seen in the Northwestern Hawaiian Islands, a nature reserve that stretches more than 1,300 miles north of the main Hawaiian Islands. The algae easily breaks off and rolls across the ocean floor like tumbleweed, scientists say, covering nearby reefs in thick vegetation that out-competes coral for space, sunlight and nutrients. (Heather Spalding/College of Charleston via AP)

  • University of Hawaii at Manoa Interim Associate Dean and Professor Alison Sherwood looks at a new species of seaweed found in the Northwestern Hawaiian Islands, Friday, June 19, 2020 in her lab in Honolulu. Sherwood, chief scientist on a study that identified the new species, said the aggressive seaweed is overtaking one of the most remote and protected coral reefs in the world. The algae forms huge, thick mats of vegetation that is killing the coral beneath it. (AP Photo/Caleb Jones)

  • This Aug. 10, 2015, aerial photo provided by the National Oceanic and Atmospheric Administration, shows the Pearl and Hermes Atoll in the Northwestern Hawaiian Islands' Papahanaumokuakea Marine National Monument. Researchers say a recently discovered species of seaweed is killing large patches of coral on once-pristine reefs and is rapidly spreading across the uninhabited atoll. (Andy Collins/NOAA via AP)

  • A thick mat of a new species of seaweed is held by a diver at Pearl and Hermes Atoll in the remote Northwestern Hawaiian Islands in June 2019. (Heather Spalding/College of Charleston via AP)

  • Divers look at a new species of seaweed covering a coral reef at Pearl and Hermes Atoll in the remote Northwestern Hawaiian Islands in August 2019. Researchers say the recently discovered species of seaweed is killing large patches of coral on once-pristine reefs and is rapidly spreading across one of the most remote and protected ocean environments on earth. The algae easily breaks off and rolls across the ocean floor like tumbleweed, scientists say, covering nearby reefs in thick vegetation that out-competes coral for space, sunlight and nutrients. (Heather Spalding/College of Charleston via AP)

HONOLULU — Researchers say a recently discovered species of seaweed is killing large patches of coral on once-pristine reefs and is rapidly spreading across one of the most remote and protected ocean environments on earth.