13 SEPTEMBER 2007
Some people find sea gulls annoying, but they have their uses.
They saved the early settlers of Salt Lake City from a calamitous cricket invasion in 1848, for example, eating the crickets before the crickets could eat all of the settlers' crops. And gulls are great for cleaning up garbage lying around beachside trash cans.
Now,
scientists say, gulls could be enlisted in a biological early warning
system for leaks of radioactive waste.
Actually, gulls can't do this job alone. They'd need help from kelp and algae, mussels and fish. The idea is that gulls would be part of a suite of species that, together, could warn humans when levels of dangerous radioactive substances begin rising in the environment and find their way into the food chain. It's all about a systematic approach to biomonitoring, rather than just happening to notice when fish start dying and plants begin withering.
"Biomonitoring can provide early warning of potential effects both for people who consume fish and wildlife from the region, as well as of potential food chain and ecosystem effects," writes Rutgers University's Joanna Berger and colleagues.
With collaborators from Vanderbilt University and the Robert Wood Johnson
Medical School in New Jersey, Berger envisions a system for carefully
choosing a consortium of species that 
can
provide sensitive measurements of radioactive substances. The researchers
explored this idea at the Aleutian island of Amchitka,
the site of three underground nuclear bomb tests from 1965-1971.
Shorebirds, algae, fish, and other aquatic life were collected from Amchitka and from the Kiska Islands, farther to the west, and were analyzed for radioactive isotopes. Some species didn't accumulate much radioactivity at all. Others were good at collecting some isotopes, but not others.
Uranium and heavier elements (known as actinides) hardly ever show up in vertebrates, for example. Algae species are active in accumulating actinides, though, in particular, the kelps Alaria fistulosa and Fucus. A valuable invertebrate to consult for actinide levels turned out to be blue mussels, as they occupy a different prominent node in the food network.
For the much lighter radioactive isotope cesium-137, algae and other invertebrates were not very effective. Here's where gulls excelled - in particular, the glaucous-winged gull (Larus glaucescens). Again, though, it's important to get data from different positions within the web of predator-prey interactions, so cesium readings are also useful from Pacific cod (a high-level predator), dolly varden (a low-level predator) and black rockfish (an intermediate-level predator.
Besides the variety in foodweb status, species were selected based on how easy they are to collect and how long they live. Fucus and Alaria are short-lived, for instance, but gulls can live for 30 or even 40 years. Black rockfish can live even longer, exceeding 50 in some cases.
"All of these species can be collected without resorting to the use of divers, which introduces its own set of health and safety issues, and adds additional costs," the researchers note in an report to be published in the Journal of Environmental Radioactivity.
After all, even when biomonitoring for radioactive wastes, you need to be practical. There is, it turns out, one invertebrate that's good at accumulating cesium - the octopus. But that was one species that did not make it to the final list. "Octopus was not proposed because of the difficulty of obtaining then with reliability," the researchers insightfully observed.
Another nominee, the sea lion, was similarly excluded.
"Although
sea lion might seem like a potential bioindicator at first glance," the
researchers wrote, "we did not propose it because their populations are
declining [and] they are difficult to collect without impacting behavior
and colony structure."
Of course, as the researchers noted, the suite of species suitable for Amchitka may not be the same as for other possible nuclear power facilities or waste dump sites. The value of their research, the say, lies in the methods they used to determine which species are best for detecting which isotopes under the conditions at any particular place.
Glaucous-winged Gull (Larus glaucesens) from USGS Alaska
Ultimately, the benefit of this method would be to provide a system for reassuring people that the environment is OK and food is safe to eat, even if nuclear installations are in the neighborhood.
"Before the U.S. and other nations can increase their dependence on nuclear power, or deal effectively with nuclear legacy wastes, the public, agencies, and public policy makers must be assured that human health and the environment are adequately protected," the researchers write. Biomonitoring, they say, offers a route to such assurance, especially when the system is designed to check on health hazards both for humans and the ecosystem itself.
"We suggest that bioindicators that represent both human and ecological health have the best chance of long-term public support," the researchers write. "Such support is particularly important not only for continued funding that will provide status and trends information, but to provide peace of mind to residents living near hazardous waste sites, particularly nuclear repositories."
In other words, it may not be so silly to put human welfare in the hands (or fins, or beaks) of certain animals. After all, it worked for Salt Lake City.
E-mail: tsiegfried@nasw.org
