Home | Contact ST  

Follow ST

Ocean Research


January 2012 Issue

Arctic Settles Into a New Phase: Warmer, Greener and Less Ice
An international team of scientists monitoring the changes in the Arctic have found that the region is entering a new, warmer state—one that brings changed ocean chemistry and less summer sea ice and snow cover. The findings were published in the 2011 edition of NOAA's annual Arctic Report Card, released in December.

The persistence of these changes is having a measureable impact on Arctic marine ecosystems. The new ocean climate is characterized by less sea ice (both extent and thickness) and a warmer and fresher upper ocean than in 1979 to 2000, according to the report.

The report also noted that minimum Arctic sea ice area in September was the second lowest recorded by satellite since 1979.

This loss of ice has led to more open sea routes. Based on passive microwave remote sensing data, the Northwest Passage and the Northern Sea Route were open in 2011 for the second consecutive year.

Phytoplankton primary production in the Arctic Ocean increased approximately 20 percent between 1998 and 2009, according to the report. This was mainly a result of increasing open water extent and duration of the open water season. The team also found that Arctic Ocean temperatures and salinity may be stabilizing after a period of warming and freshening, and increased carbon dioxide absorption has led to ocean acidification in the Beaufort and Chukchi seas. For more information, visit www.arctic.noaa.gov/reportcard.

Long-Term Effects of Fukushima Radiation in Ocean Still Unclear
Radioactive releases from the Fukushima Dai-ichi nuclear power plant into the ocean—the largest accidental marine release of radiation—are not likely to be a direct exposure threat to humans or marine life, U.S. and Japanese researchers reported in December. However, they caution there could be concern if the amount of radiation being released remains high and accumulates in marine sediments.

Discharges from the Fukushima Dai-ichi nuclear power plants peaked one month after the March 11 earthquake and tsunami and continued through at least July, according to the study, which was published in December in Environmental Science & Technology.

The report also suggested continued monitoring and bans on fishing in affected waters, given the steady elevated levels near the power plants. Because Japan has the highest seafood consumption rate in the world, understanding concentrations and assimilation in marine life is important.

Conducted by chemist Ken Buesseler of Woods Hole Oceanographic Institution, Michio Aoyama of the Meteorological Research Institute and Masao Fukasawa of the Japan Agency for Marine-Earth Science and Technology, the study compared cesium-137, cesium-134 and iodine-131 concentrations before and after the accident.

Concentrations of cesium-137, an isotope with a 30-year half-life, at the discharge point into the ocean peaked at more than 50 million times of the normal levels. Due to ocean mixing processes, the levels have been rapidly diluted off Japan's northwest coast. For more information, visit www.pubs.acs.org/journal/esthag.

Seafloor-Mapping Robot Yields Geologic Discoveries
The Monterey Bay Aquarium Research Institute's (MBARI) seafloor-mapping AUV, the D. Allan B., has finished a busy year of geologic discoveries, the institute said in December. Over the past year, the AUV had documented a huge lava flow from a three-month-old volcanic eruption and collected data that challenge existing theories about one of the largest offshore faults in Central California.

D. Allan B. carries three types of sonar, which simultaneously provide data on seafloor depth, bottom texture and sub-bottom features as little as 15 centimeters tall. The AUV is programmed at the surface, then released to fly within 50 meters of the seafloor.

In July and August, two research teams from MBARI and Oregon State University were using ROVs to study the Axial Seamount, an active volcano about 270 kilometers off the Oregon coast. After noticing several discrepancies in the seafloor's appearance compared to previous dives, the teams realized that a recent volcanic eruption had covered the seafloor with up to 3 meters of fresh lava.

In two days, the MBARI AUV had created a new bathymetric map, which allowed the team to estimate the amount of lava released during the recent eruption. They also discovered that the eruption reoccupied many of the same fissures and existing flows—data, MBARI said, that would have been impossible to gather with ROVs or sonar surveys using surface ships.

The AUV also mapped the supposed trace of the San Gregorio fault in Monterey Bay, but the sonar profiles did not show obvious signs that the fault cut through young seafloor sediments, MBARI said. This suggests that this section of the fault is improperly located on existing maps or is not as active as previously believed. For more information, visit www.mbari.org.

Groups Worry Climate Change Efforts May Neglect Acidification
Policymakers must focus more on developing measures that specifically aim to counteract ocean acidification, rather than climate change in general, the International Union for Conservation of Nature and the European Project on Ocean Acidification Reference User Group wrote in a report.

The report, published in November, urges decision makers attending the United Nations Conference on Sustainable Development, which will take place in June in Rio de Janeiro, Brazil, to address ocean acidification.

Not all approaches used to address climate change will be effective in the fight against the ocean acidification, according to the report. Measures focusing on regulating emissions of other greenhouse gases will have no impact on the progressive acidification of the ocean. The groups said that proposals for alternative geoengineering strategies aimed at reducing global temperatures through solar radiation management would not help stabilize or reduce levels of atmospheric CO2 and would be similarly ineffective in addressing ocean acidification, irrespective of any benefits and drawbacks in relation to climate change.

"Only by reducing our CO2 emissions and enhancing the protection of oceans to strengthen their ability to recover, can we effectively address this issue," said Dan Laffoley, chairman of the Reference User Group. For more information, visit www.iucn.org.


-back to top-

Sea Technology is read worldwide in more than 110 countries by management, engineers, scientists and technical personnel working in industry, government and educational research institutions. Readers are involved with oceanographic research, fisheries management, offshore oil and gas exploration and production, undersea defense including antisubmarine warfare, ocean mining and commercial diving.