ONT September 2014 : Page 28

OCEAN SCIENCE includes researchers from the Woods Hole Oceanographic Institution (WHOI), Wright State University, Observatoire Midi-Pyréneés in France, and the Royal Netherlands Institute for Sea Research appears in an edition of the journal Nature and provides the first direct calculation of mercury in the global ocean from pollution based on data obtained from 12 sampling cruises over the past 8 years. The work, which was funded by the U.S. National Science Foundation and the European Research Council and led by WHOI marine chemist Carl Lamborg, also pro-vides a look at the global distribution of mercury in the marine environment. “It would seem that, if we want to regulate the mercury emissions into the environment and in the food we eat, then we should first know how much is there and how much human activity is adding every year,” said Lamborg, who has been studying mercury for 24 years. “At the moment, however, there is no way to look at a water sample and tell the difference between mercury that came from pollution and mercury that came from natural sources. Now we have a way to at least separate the bulk contributions of natural and human sources over time.” The group started by looking at data sets that offer detail about oceanic lev-els of phosphate, a substance that is both better studied than mercury and that behaves in much the same way in the ocean. Phosphate is a nutrient that, like mercury, is taken up into the marine food web by binding with organic mate-rial. By determining the ratio of phos-phate to mercury in water deeper than 1,000 m (3,300 ft) that has not been in contact with Earth’s atmosphere since the Industrial Revolution, the group was able to estimate mercury in the ocean that originated from natural sources such as the breakdown, or “weather-ing,” of rocks on land. Their findings agreed with what they would expect to see given the known pattern of global ocean circulation. North Atlantic waters, for example, showed the most obvious signs of mer-cury from pollution because that is where surface waters sink under the influence of temperature and salinity changes to form deep and intermediate water flows. The Tropical and Northeast Pacific, on the other hand, were seen to be relatively unaffected because it takes centuries for deep ocean water to circu-late to those regions. For more information, visit www.whoi.edu. Lionfish characteristics make them more “terminator” than predator New research on the predatory nature of red lionfish, the invasive Pacific Ocean species that is decimating native fish populations in parts of the Caribbean Sea and Atlantic Ocean, seems to indicate that lionfish are not just a predator, but more like the “termi-nator” of movie fame. The finding of behavior that was called “alarming” was presented by Kurt Ingeman, a researcher from Oregon State University, at the annual meeting of the Ecological Society of America. Most native predatory fish are attracted to prey when their numbers are high, when successful attacks are easy, and when a minimum of energy is need-ed to catch and eat other fish, according to previous research done by Michael Webster, a fish ecologist who received his doctorate from OSU. As the popula-tion of prey diminishes, the native predators often move on to other areas where, literally, the fishing is better. The new research concludes that lionfish, by comparison, appear to stay in one area even as the numbers of prey diminish, and in some cases can eat the population to local extinction. They have unique characteristics that make this possible, and, like the terminator, they simply will not stop until the last of their prey is dead. “Lionfish seem to be the ultimate invader,” said Ingeman, a doctoral can-didate in the Department of Integrative Biology within the OSU College of Science. “Almost every new thing we learn about them is some characteristic that makes them a more formidable predator. And it’s now clear they will hunt successfully even when only a few fish are present. This behavior is unusu-al and alarming.” This research was conducted on replicated natural reefs in the Bahamas, measuring prey mortality of the fairy basslet–a popular aquarium fish and a common prey of lionfish. 28 Ocean News & Technology This summer Thomson is part of an international group led by the UW that is putting dozens of sensors in the Arctic Ocean to better understand the physics of the sea-ice retreat. “There are several competing theo-ries for what happens when the waves approach and get in to the ice,” Thomson said. “A big part of what we’re doing with this program is evalu-ating those models.” He will be out on Alaska’s northern coast from late July until mid-August deploying sensors to track waves. He hopes to learn how wave heights are affected by the weather, ice conditions and amount of open water. “It’s going to be a quantum leap in terms of the number of observations, the level of detail and the level of precision” for measuring Arctic Ocean waves, Thomson said. The other author is W. Erick Rogers at the Naval Research Laboratory. The research was funded by the U.S. Office of Naval Research. For more information, visit www.washington.edu. Study shows three times more mercury in upper ocean since Industrial Revolution Although the days of odd behavior among hat makers are a thing of the past, the dangers mercury poses to humans and the environment persist. Mercury is a naturally occurring ele-ment as well as a by-product of such dis-tinctly human enterprises as burning coal and making cement. Estimates of “bioavailable” mercury – forms of the element that can be taken up by animals and humans – play an important role in everything from drafting an international treaty designed to protect humans and the environment from mercury emissions, to establishing public policies behind warn-ings about seafood consumption. Yet surprisingly little is known about how much mercury in the envi-ronment is the result of human activity, or even how much bioavailable mercury exists in the global ocean. Until now. A new paper by a group that September 2014

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