How an Earthquake in Japan Triggered an Algae Invasion in the Pacific Northwest
In 2011, a colossal tsunami set off by a magnitude 9.0 earthquake slammed into the eastern shores of Japan. Not long afterwards, some of the 1.5 million tons of floating debris created by the waves, from buoys and boats to entire fishing docks, began washing up along Americaâs northwest Pacific coast.
A s revealed by a recent study, dozens of species of algaeâ"globally abundant, as well as those found in Asia and across the northern Pacificâ"snuck along on this debris and turned up in Oregon and Washington. Spending several years collecting, classifying and observing these tiny beasties, researchers found that most of them were opportunists that had arrived in an environment not dissimilar from their starting points. Had they been given the chance, a full-scale invasion of this brave new world might have taken place.
Algae might not sound like much of a danger, but donât forget that these little critters can disrupt entire regions when they get out of hand. Just look offshore from Floridaâs gulf coast, where a red tide bloom has slaughtered wildlife and devastated the tourist industry. Itâs even become a hot button issue for voters there in this weekâs midterm elections.
Thatâs why this (fortunately averted) incursion matters. Writing in the journal Phycologia, the researchers suggested that if it werenât for an extensive and prompt clean-up operation, many of the invaders were likely to have quickly colonized their landing sites.
Although itâs been previously acknowledged that species can ride buoyant debris thousands of miles across the ocean, a 2017 study on the Japanese tsunami was one of the first to document it happening in real time over such a huge scale. It revealed that nearly 300 larger species, from crabs and sea stars to sponges and fish, turned up alive in North America and Hawaii.
This new study proves to be an equally eye-opening companion piece.
Lead author Gayle Hansen, a marine phycologist at Oregon State University (OSU), explained that the first piece of biota-carrying debris found was the Agate Beach dock, which turned up in June 2012, just over a year after the tsunami occurred. Immediately starting to gather specimens, they ultimately captured 42 pieces of debris between 2012 and 2016 a s they washed up in the Pacific Northwest.
The debris were found to contain a staggering 84 different species and varieties of algae and cyanobacteria. âWe did not expect debris to arrive with hitch-hiking biota as we did not think the Japanese species would survive the cross-Pacific journey,â she told Earther.
Of these, 83 percent were reproductive and dropping spores on examination, while all were capable of becoming fertile. Although many were short-lived, they often had a high colonization potential. Some species had been seen in the Pacific Northwest before, but others were alien, and several were known to be incredibly effective at invading new territory. All things considered, Gayleâ"along with colleagues at Kobe Universityâ"concluded that 49 percent of the species that arrived represented an invasion threat to the region.
This invasion may have been cancelled, but Hansen referred to numerous earlier examples that hint at what may have transpired. A classic example can be found in Hawaiiâs Caulerpa taxifolia algae: after having been accidentally introduced to the Mediterranean by an aquarium, it colonized large swaths of the shallow subtidal area, outcompeting the local seagrass. The fish, not willing to eat the toxin-producing invader, experienced a precipitous decline in their populations.
John Chapman, a fisheries expert at OSU not involved in the new workâ"and an author of last yearâs tsunami rafting studyâ"told Earther that the environmental threats from introduced algae âare very likely underappreciated.â
Chapman noted that the vast majority of algae are small, which makes them difficult to identify or even detect. This study also foun d that the smaller species proved to be the longer-term survivors, and were more likely to succeed in invading. This is all problematic, as these critters are likely to be influencing ecosystems in ways that arenât yet recognized.
And tsunamis are just one part of the problem. Chapman noted that hurricanes, floods, mudslides and âpure human messinessâ all generate floating debris, which is building wider bridges between continents that âan enormous diversity of organisms are riding.â
This article has been updated to clarify that 83 percent of algae varieties the researchers examined were actively reproductive, while all were capable of becoming fertile.Source: Google News Japan | Netizen 24 Japan