'An island of organisms'.
Fishing floats, driftwood, bottles, plastic foam. Floating debris from Asia has washed ashore in Oregon for millennia. So why does a Japanese dock that grounded at Agate Beach on June 5 present a sudden and severe threat of invasive species?
The short answer: "We don't know," says John Chapman, an invasive species expert at Oregon State University's Hatfield Marine Science Center in Newport.
The 132-ton dock broke from its moorings during the earthquake and tsunami that struck Japan in March 2011. When the floating dock arrived on the Oregon Coast, it carried 13 pounds of marine organisms per square foot. Scientists counted at least 20, and possibly as many as 50, species foreign to Oregon waters - "an island of organisms," Chapman says - including a number that are known to present a threat to native ecosystems.
Chapman says the conventional wisdom had been that plants, algae, mollusks and other creatures attached to Asian debris would be starved off, scoured away and replaced by colonies of open-sea organisms by the time they reached North America. The dock is forcing scientists to reassess this understanding. With an estimated 1.5 million tons of earthquake and tsunami debris still on its way, protecting native environments will require more preparation and response than was earlier expected.
To their credit, the Oregon Department of Fish and Wildlife and the state Parks Department recognized the danger early; they sent crews with scrapers and blowtorches to remove the alien arrivals from the dock's surfaces. Workers buried 4,000 to 5,000 pounds of marine creatures above the high tide line. But it's possible, even likely, that some organisms got away and will become established.
One pressing question is whether the dock is unique, or at least a rarity. The dock may be big enough, and may have made the ocean crossing quickly enough, to present an uncommon opportunity for survival of Asian marine species. The dock also could have become home to an unusually rich community of subtidal and intertidal organisms before being torn loose. The worst possibility is that the months ahead will prove that the dock brought the first of many cargos of creatures capable of finding niches in local ecosystems, sometimes at the expense of native species.
Invasive species show up regularly in Oregon waters. The usual source is ballast water from ships. Chapman finds a new one in Yaquina Bay about once a year; the latest is a parasite capable of wiping out native shrimp. While the problem is not new, the diversity and number of passengers aboard the dock - their variety can be appreciated by visiting a photo gallery at rgne.ws/L9a03C - presents an elevated risk, and Oregon needs to brace for it.
Already, the Marine Science Center is working to identify the species found aboard the dock and assess the threat. Federal, state and local agencies, anticipating the arrival of a big disposal problem in the aftermath of the earthquake and tsunami, now find themselves confronted with a broader and unexpected task of environmental protection.
Coastal residents and visitors can help by watching for debris on shore and at sea, reporting it to authorities and, Chapman advises, leaving it and any life forms attached in place. The first "island of organisms" may not be the last.