Using Microwaves To Cook Ballast Stowaways

Smivs writes "US researchers say they have developed an effective way to kill unwanted plants and animals that hitch a ride in the ballast waters of cargo vessels. Tests showed that a continuous microwave system was able to remove all marine life within the water tanks. The UN lists 'invasive species' dispersed by ballast water discharges as one of the four main threats to the world's marine ecosystems. For example European zebra mussels (Dreissena polymorpha) have infested more than 40% of the US's inland waterways. Between 1989 and 2000, up to $1B is estimated to have been spent on controlling the spread of the alien invader."

Comments

Too little too late

[dreamchaser]

Even if this works, in many cases invasive species are already well entrenched and the damage is done. The example cited of the zebra mussels, for instance, has created a huge problem for some inland fisheries in the US. The problem has been known for years but nobody has really tried to do much about it until now.

Re:Too little too late

[NeutronCowboy]

Yes, it has. Snakes were introduced into one of the Indonesian islands to deal with an introduced toad. Turns out that some of the indigenous animals were a lot easier for the snakes to catch. As a result, the local animal life is not only threatened by the toads, but also by the snake. If I'm off on the details, my apologies - I couldn't find the original story. This isn't the only story though. There have been a few attempts to introduce natural predators, and they've generally all turned up atrocious and unpredicted side effects. The reason this isn't done is because it's been tried before, and the end-result wasn't any better.

Re:Too little too late

[Aydsman]

Some environmentalist has to tell me why we don't just import its natural predator. And don't give me crap about 'well it could be an invasive species too.' If it's high up the food chain, it will be forced to live in equilibrium with its prey. Has it ever even been tried? Well in other cases, yes - it has been tried. Unfortunately that hasn't worked out so well.

Re:Too little too late

[belmolis]

The problem is that predators usually are not restricted to a single kind of prey, so they will not only control the organism you want to get rid of but prey on indigenous species that you don't want it to. A case in point is the rabbit problem in New Zealand, which has no indigenous mammals. Introducing predators such as foxes or coyotes is not an acceptable solution because they will also eat the various species of flightless birds. Even when there is a specialized predator, it is very difficult to be sure that it will stay specialized.

Re:Too little too late

[Fifth Earth]

The problem is most high-level predator species don't eat only one thing. Whenever this is tried, invariably the predator species eats some of the invasive species, but also eats ALL of some other native species.

Even if the predators are able to effectively kill off the invader (which they often aren't), and they don't just switch to some other native species, then the predators start dying too. Eventually, the predator goes extinct due to lack of food supply, but some small portion of the original invader remains to repopulate, and the problem remains unsolved.

Honestly, nobody has ever succeeded in controlling an invasive species once it becomes established, using any method. In that light, you may as well avoid control methods that are known to have massive collateral damage.

Re:Too little too late

[Anonymous Coward]

Cane toad ( Marine toad in USA ) introduced to control cane beetle. The toad can't jump more than a few centermeters while the beetle lives near the top of the cane. Also the toad doesn't like cane fields and preferes waterways

It wasn't the best laid out plan.

If you do introduce a predator you have to ensure it is specialized for the target species and can not adapt to other creatures. The only sucessful release that I know of is the cactoblastis beetle which almost wiped out the pickly pear introduced into australia. Reminant populations still remain

Re:Too little too late

[dfm3]

That's not quite true. I work in the plant pathology field of study and introducing a predator species as a biological control of a pest is a fairly accepted practice. For example, a group at Virginia Tech is currently working with species of Laricobius, a beetle which is a predator of the hemlock woolly adelgid.

Of course, if you are going to be introducing a non native species, you'd better be absolutely sure you know what you're doing. There are countless regulatory obstacles that typically need to be overcome, too, and it can take years before a species is approved to be released from quarantine into the field, if it ever is.

Typically, an introduced organism becomes a pest for one of two reasons: 1) it's a generalist that is a better competitor for resources than existing species (as is the case with the zebra mussel, which is unbelievably effective at filtering particulate organic matter from the water and subsequently undergoing rapid population growth) or 2) it becomes a pest or pathogen of a particular existing species. Many introduced plant pathogens fall into this second category- they have no natural predators in the new environment, as well as a food source that has not evolved any defense mechanisms against them. The balsam woolly adelgid or the chestnut blight fungus are two examples of the latter.

Although there are probably cases where introducing a new predator species can cause more problems than it solves (remember that Simpsons episode?), with careful planning and understanding of the ecology of the organism, such issues can hopefully be avoided. Usually, we err too far on the side of caution by choosing a species that is too much of a specialist, and we don't get the results we would hope for. Remember the Laricobius beetles I mentioned earlier? One problem with them is that they are so specialized, that when the hemlock woolly adelgid starts to become scarce the beetles have no other food source and begin to decline as well. They have no other food source, and thus have essentially no effect on existing native species.

Re:Mussels?!

[FooAtWFU]

Can we eat them? Problem solved. No, not really. They filter tons of water and end up collecting all sorts of contaminants, for one thing. They're a royal pain to remove from any surface, for another, very small, and very sharp.

What can happen using low tech

[rwa2]

To anyone concerned about frying the microbes, Wired had a very readable story on what can happen sometimes when the ballast is handled the conventional way:

http://www.wired.com/science/discoveries/magazine/16-03/ff_seacowboys?currentPage=all

*spoiler* essentially current cargo ships headed to the U.S. have to flush their ballast in international waters and refill with local seawater. The Cougar Ace somehow managed to screw up this step and went askew (see pic). There were many quite grave consequences.

Granted, it's not standard operating protocol to end up with losses like this just too keep out invasive species, but it does illustrate some of the challenges and extent of trouble people go to to comply with this kind of ecological directive. Plus it was a damn well-written story I enjoyed reading.

Another way - Use nitrogen.

[robbak]

Another way that has been suggested is to bubble pure nitrogen through the ballast water.

It purges the water of oxygen, killing any marine life. It also has the benefit of stopping corrosion.

It does have the downside of making the ships hull an instant death (asphyxiation) hazard.

swish and spit...

[pointbeing]

I live in Michigan and this problem's been aired on local NPR for the last few days - introducing foreign marine life into the Great Lakes has been a problem for years.

Starting this year cargo vessels are required to "swish and spit" - flush their ballast tanks 200 miles before entering the St. Lawrence seaway.

This probably doesn't do much good for saltwater invasive marine life but is a good solution for the freshwater nasties.

Re:Life, lemons and unexpected outcomes

[tomhudson]

You're looking for the EPA study ... http://www.epa.gov/glnpo/glwqa/usreport/part5.html

Zebra mussels continue to profoundly affect the Great Lakes ecosystem. This prolific mollusk filters microscopic algae from the water column, diverting nutrients from open water to lake bottom systems, thus favoring bottom-feeding fish (and their predators) over those such as alewife and smelt (and their predators) which feed in the open water. Aquatic rooted plants (macrophytes) and their communities (e.g. large mouth bass) thrive in water cleared by zebra mussel, while habitat is reduced for species adapted for turbid waters (e.g. walleye).

In other words, some fish benefited, others didn't.

In general, community abundances tended to increase at zebra mussel sites, but the diversity within those communities decreased.

In other words, more zebra mussels == more fish. The lessened diversity could easily be explained by the fact that it takes time for these things to shake themselves out.

Studies on the population dynamics of burrowing mayflies conducted by the Pennsylvania Department of Environmental Protection (PADEP), the Biological Resources Division of the USGS, Heidelberg College, the Ohio State University, and Penn State University have indicated that the mayfly populations in western Lake Erie and the Presque Isle Bay AoC are presently experiencing exponential growth. Based on population models, the mayfly population is predicted to attain full recovery by the year 2002. Mayflies were virtually eliminated from the western basin of Lake Erie by 1960, but recolonization began during the 1990s and spread throughout most of the lake by 1996. The recovery of the mayfly augers well for the yellow perch population which is expected to grow as the density of mayfly nymphs continues to rise in western Lake Erie. The re-emergence of the mayfly is seen as a prime indicator of improved water and sediment quality in Lake Erie.

Maybe those nasty zebra mussels can be given some credit for making the water clean ... it's not like people were going to pay to set up a massive filtering system ...