Sea Technology

JUL 2013

The industry's recognized authority for design, engineering and application of equipment and services in the global ocean community

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showed that this kind of camoufage outperforms the mirror strategy by up to 80 percent. It has been assumed that the best camoufage strategy for open-ocean fsh is to refect sunlight like a mirror. Many fsh, including the lookdown, have refective skin elements that can act like mirrors. Such a strategy works well for certain aspects of light, such as color and intensity, which tend to be distributed homogeneously in the region surrounding the fsh. The mirror strategy is not optimal, however, when light is polarized, which occurs when individual waves of light align parallel to one another. The study was published in the Proceedings of the National Academy of Sciences. The research was funded by the U.S. Navy, which has an interest in developing better ocean camoufage technologies and being able to detect such strategies if they are developed by others. The researchers' next task is to understand how the fsh are accomplishing this camoufage. Ice Tubes Provide Clues To Origin of Life Life on Earth may have originated with tubes of ice that grow downward into cold seawater near the Earth's poles, scientists reported in an article on brinicles, which appeared in Langmuir. Scientists know little about brinicles, which are hollow tubes of ice that can grow to several yards in length under pack ice. The analysis concluded that brinicles provide an environment that could have fostered the emergence of life on Earth billions of years ago, and it could have done so on other planets as well. Beyond Earth, the brinicle formation mechanism may be important in the context of planets and moons with ice-covered oceans, particularly Jupiter's Ganymede and Callisto. Study Shows Change in Oceanic Food Web A study on the endangered Hawaiian Petrel by scientists from Michigan State University, the Smithsonian Institution and eight other organizations has found a shift in bird foraging habits that is likely linked to industrial fshing in the Pacifc. The research looked at the chemistry of feathers and bones of modern Hawaiian Petrels, as well as bones from subfossils up to 4,000 years old, to determine where on the food chain and in the Pacifc Ocean the birds have been foraging throughout the centuries. Scientists extracted protein from the bones and feathers of the birds to study stable isotopes of carbon and nitrogen in the protein. In older samples, nitrogen isotope ratios were consistently high, indicating a diet of relatively large prey high on the food chain. Those less than a century old, after industrial fshing had started, had low ratios. This suggested a shift to smaller fsh, squid and other prey lower on the food chain. The study examined isotope data from more than 250 individuals, including birds from every known modern and ancient Hawaiian Petrel population. The scientists studied a chronology of samples that refected conditions both prior to and following human presence in the northwest Pacifc Ocean. The Hawaiian Petrel is a crow-sized oceanic bird found throughout the northeast Pacifc. n 62 st / July 2013 www.sea-technology.com

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