How Mercury Gets into Seafood
Scientists have known how mercury from industrial pollution affects local freshwater ecosystems and poses a human health threat [see “Mapping Mercury”; SciAm, September 2005]. New data reveal just how the mercury cycle functions in the ocean. Based on samples from 16 sites from Hawaii to Alaska and on computer simulations, researchers at the U.S. Geological Survey and other institutions conclude that bacterial decomposition of algae that have sunk from the surface to mid-depth plays a crucial role. In the presence of mercury, which in this study came from Asia via ocean currents, the decomposition process creates methylmercury, which works its way up the food chain and into predators such as tuna. The study, in the May 1 Global Biogeochemical Cycles, also finds that the North Pacific has seen a 30 percent rise in mercury contamination since the mid-1990s.
More Choices, More Happiness?
Having too many options can leave people less happy with the decisions they ultimately make [see “The Tyranny of Choice”; SciAm, April 2004]. Experiments described in the March Psychology and Marketing attempt to reconcile those findings with theories from psychology and economics that equate more choices with greater satisfaction. In one test, participants had to pick a charity to which to donate money from a list of either five or 40 organizations. The study found no evidence of the too-much-choice effect even in the more plentiful option, except when participants were asked to justify their picks. Under those circumstances, they seemed less satisfied with their decisions, because they had to recall the choices they could have made. The researchers suggest that the too-much-choice effect may occur only under certain conditions and is less robust than previously thought. —Kathryn Wilcox
Off the List
Thanks to repopulation efforts during the past few decades, the gray wolf (Canis lupus) now thrives in the U.S., and since 2003 the U.S. Fish and Wildlife Service has been trying to move the top predator off the endangered species list—a plan opposed by groups that believe the wolves are susceptible to being overhunted [see “Out of the Woods”; SciAm, April 2003]. But this past April the service largely succeeded, determining that enough wolves live in key areas and that they can be managed by most state wildlife departments. The agency still plans to monitor the wolves for the next five years and can place them back on the list at any time. —Kathryn Wilcox
Good for a Few More Years
The crew of the space shuttle Atlantis hauled in the Hubble Space Telescope on May 13 to service the venerable instrument for the fifth and final time. NASA originally scrapped the dangerous mission in the wake of the Columbia disaster in 2003, but public and political pressure won out. Besides maintenance and upgrades, Hubble got new instrumentation that will penetrate deeper into the void at near-infrared wavelengths, thereby providing a glimpse back in time to about when the universe was 500 million years old. If all the fixes work, Hubble should continue burnishing its impressive résumé of discoveries [see “Hubble’s Top 10”; SciAm, July 2006] until at least 2014, by which time its successor, the James Webb Telescope, will also be in orbit.
Note: This article was originally printed with the title, "Updates."