SCIENTISTS : REEF THREAT ALARM : HAWAII

On a routine trip to monitor wildlife near the northwestern Hawaiian islands in 2016, researchers noticed that small patches of red algae they had never seen before, growing on the coral reef.

When they returned last summer, the algae had spread exponentially. Mat-like layers now cover vast swathes of coral in the Pearl and Hermes Atoll, a remote, uninhabited portion of the protected Hawaiian islands around 1,200 miles from Honolulu.

The prolific growth is a previously undiscovered species, according to a study published this month from researchers at the University of Hawaii.

Scientists say the new species poses a threat to coral and other marine life in the area.

''Something like this has never been seen in the northwestern Hawaiian Islands before,'' said Allison Sherwood, head researcher of the study. ''This is extremely alarming to seen an algae like this come in and take over so quickly and have these impacts.''

Scientists determined that the algae, which they named Chondria tumulosa, didn't match any known species, Dr. Sherwood said.

Though it behaves like an invasive species, disrupting its new environment, it cannot be labelled one because it hasn't been traced to an outside source. Scientists instead refer to it as a nuisance species.

The algae's sudden appearance and rapid spread are cause for concern, Dr. Sherwood said.

Algae growing on coral blocks sunlight, essentially smothering the coral and anything else living underneath it, Dr. Sherwood said. It takes up space where other algae or seaweed species that feed herbivores would naturally grow.

''It's essentially changing the entire community composition there and that's going to have ripple effects up through the food chain,'' Dr. Sherwood said.

The Pearl and Hermes Atoll is found within the Papahanaumokuakea Marine National Monument, a World Heritage site and protected marine sanctuary that encompasses the northwestern Hawaiian Islands.

Randall Kosaki, the deputy superintendent of the monument for the National Oceanic and Atmospheric Administration, was chief scientist on the cruise that discovered the algae.

It took the team four days by boat to reach the Pearl and Hermes Atoll.

''This is an organism that has the potential to completely overrun an entire island or an entire atoll,'' Dr. Kosaki said. ''Whether it will do it or not, time will tell.''

In marine environments, invasive species spread so easily that once a species gets into the ecosystem, there's virtually to be done, he said. ''Prevention is the only tool in our toolbox.''

To ensure that they did not spread the algae to other islands when they returned to Honolulu, the researchers doused their dive gear in bleach.

''God forbid that we bring this back to Oahu or Waikiki, where the consequences would not just be an ecological disaster, because Hawaii's economy is so heavily based on tourism,'' Dr. Kosaki

The World Students Society thanks author Marie Fazio.