Aggressive seaweed smothers one of world's most remote reefs
by Caleb Jones
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.
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 study was Midway Atoll, site of a pivotal World War II air and sea battle, Pearl and Hermes Atoll is mid-Pacific about 2,000 miles (3,200 kilometers) from Asia and North America.
The uninhabited atoll is in the 600,000-square-mile (1.6 million-square-kilometer) Papahanaumokuakea Marine National Monument, one of the world's largest protected marine environments.
Noting that individual mats of seaweed were as big as several soccer fields, researchers say the algae could dramatically alter Pearl and Herme's reef and threaten the entire Hawaiian archipelago if it spreads.
Hawaii's main islands have several established invasive seaweeds, but cases in the remote northwest are rare.
"We have, not until now, seen a major issue like this where we have a nuisance species that's come in and made such profound changes over a short period of time to the reefs," said University of Hawaii at Manoa Interim Associate Dean and Professor Alison Sherwood, chief scientist on the study.
Researchers studied the seaweed's DNA to try to determine its origin but concluded it's a new species of red algae they named Chondria tumulosa.
The algae can spread in various ways, Sherwood said. It produces tumbleweed-like clumps that move around the immediate area, but it also generates spores that could be traveling much greater distances.
Among the unknowns are why the algae is growing so fast and how it reached such a remote place.
Scientists say seaweed blooms happen worldwide and can be seasonal, but this does not appear to be the case. The National Oceanic and Atmospheric Administration has been monitoring the site for over 20 years.
"When you see something unusual in the last few years, you can be pretty sure that this is something that's a bit special as opposed to just things that change from year to year," said University of Queensland Professor Peter Mumby, who is also chief scientist for Australia's Great Barrier Reef Foundation. "But it is a matter of concern whenever you see an ecosystem start to display symptoms ... like this."
Mumby, who was not involved with the Hawaii research, said more needs to be done to understand what is driving the seaweed growth.
But he noted that in other parts of the world algae blooms often occur because fish that eat the plants have been harvested or forced to relocate by environmental changes.
The new seaweed could have been introduced by a boat or marine debris. But there is no fishing allowed at Pearl and Hermes, and any ship that enters the region is required to have been inspected and cleaned. The species could also be native, having lived in small, unseen nooks and crannies before a change in local conditions caused it to bloom, researchers said.
The NOAA research crews will soon return to study the outbreak and find out if currents have spread it to nearby Midway, home to the Battle of Midway National Memorial, a U.S. Fish and Wildlife Service base and the region's only airstrip.
The first order of business, officials say, is to ensure anyone studying the seaweed doesn't inadvertently spread it.
"All of our dive gear, all of our boats, everything got saturated with bleach," said Randall Kosaki, NOAA research coordinator at the marine monument and expedition lead for the earlier surveys.
"If something like this got back to Waikiki or anywhere in the main Hawaiian Islands it would be an ecological disaster, but also an economic disaster," Kosaki said. "You can imagine what that would do to tourism to have an algae like this overgrowing the reefs."
Let us know if there is a problem with our content
Use this form if you have come across a typo, inaccuracy or would like to send an edit request for the content on this page.
For general inquiries, please use our contact form.
For general feedback, use the public comments section below (please adhere to guidelines).
Thank you for taking time to provide your feedback to the editors
Your feedback is important to us. However, we do not guarantee individual replies due to the high volume of messages.
Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics.
Phys.org is a part of Science X network.
With global reach of over 5 million monthly readers and featuring dedicated websites for hard sciences, technology, smedical research and health news,
the Science X network is one of the largest online communities for science-minded people.