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Ocean Research


July 2013 Issue

Deep Biosphere Study Looks into mRNA
The deep biosphere—the realm of sediments far below the seafloor—harbors a vast ecosystem of bacteria, archaea and fungi that are actively metabolizing, proliferating and moving, according to a new study by scientists at Woods Hole Oceanographic Institution and the University of Delaware.

The researchers analyzed messenger RNA (mRNA) from different depths in a sediment core collected off the coast of Peru in 2002. mRNA is sought by microbial ecologists because it carries instructions for proteins the cells are making, which gives researchers information about the biochemical mechanisms and processes the organisms are using to function.

Because the metabolic rates in the deep biosphere are very low and mRNA is present in small amounts—only 4 to 10 percent of the total RNA in most environmental samples—extracting enough of it to analyze from deep sediments is difficult.

The group found mRNA related to cell division at all depths tested, ranging from 5 to 159 meters below the seafloor. It was most abundant in zones where cell numbers were the highest, which indicates that the larger cell populations there were likely due to dividing cells. The study also identified mRNA for biochemical pathways that reveal information about the workings of the deep biosphere ecosystem and its significance to global cycles.

Tideland Solar Buoys Mark Wrecks in Arctic
Two SB-138P polyethylene buoys with solar-powered ML-140 LED lanterns from Tideland Signal (Houston, Texas) are being used to mark wrecks in the approaches to the port of Narvik in the far north of Norway.

The new SB-138P buoys are replacing old battery-operated steel buoys from the 1980s that required maintenance and battery changes.

The buoys are acting as wreckmarkers for the British 8,770-ton iron-ore carrier Romanby and the Swedish 8,855-ton iron-ore carrier Stråssa. Both vessels sunk in Narvik inner harbor during a World War II battle on April 10, 1940.

Both buoys carry Tideland ML-140 lanterns fitted with a MaxiHALO-60 LED flasher, giving a range of 4 nautical miles. Solar panels with a total capacity of 70 watts are mounted on the tower section of the buoy, feeding a 200-ampere-hour battery housed within a watertight compartment. The MLED-140 MaxiHALO configuration combines MaxLumina lenses with LED technology.

Researchers Discover New Fish Camouflage
Fish can hide in the open ocean by manipulating how light reflects off of their skin, according to researchers at the University of Texas at Austin. The discovery could lead to the development of new camouflage materials for use in the ocean.

The researchers found that lookdown fish camouflage themselves through the manipulation of polarized light after it strikes the fish's skin. In laboratory studies, the researchers showed that this kind of camouflage outperforms the mirror strategy by up to 80 percent.

It has been assumed that the best camouflage strategy for open-ocean fish is to reflect sunlight like a mirror. Many fish, including the lookdown, have reflective 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 fish. 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 camouflage technologies and being able to detect such strategies if they are developed by others.

The researchers' next task is to understand how the fish are accomplishing this camouflage.

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 fishing in the Pacific. 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 Pacific 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 fishing had started, had low ratios. This suggested a shift to smaller fish, 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 reflected conditions both prior to and following human presence in the northwest Pacific Ocean.

The Hawaiian Petrel is a crow-sized oceanic bird found throughout the northeast Pacific.


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