Formidable Invasive Species Won't Be Easy to Keep Out of Great Lakes

CAN WE PROTECT THE GREAT LAKES FROM A NEW WAVE OF INVASIVE SPECIES?

The Earth is teeming with indomitable beasts, but nothing — not the polar bear, not the crocodile, not the anaconda — matches the ferocity of the microscopic tardigrade when it comes to doing whatever it takes to survive.

Also known as "water bears" or "moss piglets," tardigrades can survive an oven broiler. They can weather temperatures hundreds of degrees below zero. They can be found scrambling across mountainsides in the high Himalayas and mucking about in ocean canyons two miles deep.

These eight-legged waddlers that feast on bacteria captured the imagination of the science world in 2007 when European researchers went to astronomical lengths to destroy them.

They put a platoon of slumbering tardigrades on a rocket in Kazakhstan, blasted them into space and exposed them to everything the cosmos could throw at them. A person will wither within seconds if left unprotected in the vacuum of the universe; these tardi-nauts were left drifting across the devilishly frigid, cosmically radiated heavens in an open satellite compartment for 10 days.

"Then they brought them back," says University of Wisconsin-Milwaukee professor and zooplankton specialist Rudi Strickler, "and they woke up and walked around."

Not all the tardigrades survived, but among those that did were a group robust enough to have perfectly healthy offspring.

Strickler, a Swiss-born researcher, likes to think about tardigrades when he thinks about what it will take to protect ecosystems like the Great Lakes from being invaded by exotic organisms hitchhiking in the bowels of an overseas freighter's ballast tanks.

Ballast water is held in special tanks on a ship to balance uneven cargo loads and stabilize empty vessels on the open seas. The problem is ships suck up more than just water when they fill those tanks. They can also bring aboard any life that might be lurking in foreign ports, including fish, mollusks, crustaceans, plants, viruses, even deadly bacteria.

When ballast is discharged in exchange for cargo at a Great Lakes port, those accidental travelers can colonize new waters.

There are some 1,000 different species of tardigrades, some of which are so small they could be padding about on the period at the end of this sentence. While they don't pose an obvious threat to the Great Lakes — some species of tardigrades already call the region home — Strickler says it's necessary to consider their tenacity when trying to draw up a ballast battle plan against nature's spectacular array of life.

"Don't pick the ones that you can beat up easily," he says. "Pick ones that know all the tricks of life."

'Haphazard' hunts for fresh invasions

The pace of invasive species being discovered in the Great Lakes peaked about a decade ago, when a new invader was detected, on average, more than once a year.

To stanch the onslaught, starting in 2008 all Great Lakes-bound overseas vessels were required to flush their ballast tanks in mid-ocean to expel any ballast dwelling organisms, or kill them with a blast of saltwater. No new invader has been detected in the lakes since — a point shipping industry advocates are quick to tout.

Graphic

:How ballast delivers invasive species into Great Lakes waters

Research shows that a saltwater ballast flush can go a long way in killing most freshwater tank dwellers. But most biologists don't think that's enough because even if flushing ballast tanks with saltwater eliminates 98 or even more than 99% of certain classes of hitchhikers, boats arriving from ports around the globe are far from sterile.

One Great Lakes-bound freighter can carry enough ballast to fill 10 Olympic-size swimming pools. These tanks can hold not only water but also swamps of sediment that can be teeming with all manner of organisms in all different life stages, from fish eggs to microscopic zooplankton to dormant cysts that evolved over millions of years to survive most anything nature can toss at them.

A 2011 federal report looking at the threat of ballast water to all U.S. ports noted that a study conducted in Australia revealed that sediments from just one freighter ballast tank can harbor up to 300 million viable cysts of primitive dinoflagellates, which scientists dub the "cells from hell" because they can produce a deadly neurotoxin. So a flush that eliminates 99% of this ballast tank's inhabitants could still carry 3 million potential invaders

Skeptical scientists

The federal government acknowledges the weakness of relying solely on ballast water flushing to protect the Great Lakes as well as other U.S. bodies of water. In December, the Environmental Protection Agency, in an out-of-court settlement following more than a decade of legal battles with environmentalists, adopted a new permit requiring ocean freighters visiting all U.S.ports to install ballast disinfection systems.

The problem is the EPA concedes that a "reasonable potential" exists for new invasions even after the ships install the required treatment equipment, which uses things such as chemicals, filters and UV light. The installation process alone could take the better part of a decade, thanks to a grace period given to the shipping industry.

The EPA blames the problem on a lack of technology to adequately disinfect a ballast tank. Both it and the U.S. Coast Guard, which has adopted similar regulations, have decided that the best that existing treatment technology can do is begin to chip away at the problem.

For organisms 50 microns or greater — the thickness of a newspaper page is about 70 microns — ships can discharge fewer than 10 living specimens per cubic meter of water. For smaller organisms — between 10 and 49 microns — the limit is 10 million per cubic meter.

While these treatment standards should reduce the amount of life that would normally be spilling out of ballast tanks, think of the problem like a campfire.

The EPA's treatment requirements are a little like the first gallon of water you slosh on the fire at the end of the night to knock back the flames. It will take more gallons to properly soak the embers to ensure you've snuffed their glow. Then it might take a few more gallons before you kill the telltale hiss and can go to bed sleeping with the knowledge that your fire isn't about to become someone else's problem.

It would, of course, be impossible to design a ballast treatment system that is 100% fail-proof. The goal is to get as close to that as possible, and critics say the new treatment standards do not get us there.

The EPA itself asked the panel of scientists to assess whether treatment systems could meet standards that are 10, 100 or 1,000 times more stringent than those the EPA ultimately adopted, and the agency said the answer it got back was no.

"The numeric limitations in today's permit represent the most stringent standards that ballast water management systems currently safely, effectively, credibly and reliably meet," the agency proclaimed in announcing its new treatment requirements.

Not true, said many of the scientists on that panel.

"The (panel) did not reach that conclusion," eight of the panel's 21 scientists wrote in a letter submitted as part of the public comment process on the EPA's new ballast regulations. The scientists claim far more effective treatment systems may indeed be available, particularly if the EPA had given adequate consideration to having ships discharge their contaminated ballast water to on-shore treatment facilities similar to sewage treatment plants.

The scientists noted that EPA's new regulations will reduce a typical ship's ballast tank population by 30 times for organisms 10 to 50 microns in size and by 500 times for larger organisms. But, they wrote, on-shore treatment systems can reduce those life forms by at least 30,000 times.

"The stakes could not be higher," the scientists wrote, noting that the EPA discharge standards are likely to stick for years, leaving the nation's waters unduly exposed to new invasions the whole time.

Source: Journal Sentinel

Here's The Bitly Link to Include In Your Share: http://bit.ly/WMVnMP

Media

Taxonomy

• Environment
• Conservation
• Lake Management