Weekly Ocean News

DATASTREME OCEAN WEEK FOUR: 13-17 February 2006

Ocean in the News

(Thurs.) Canadian seal population at mercy of unusual weather -- Wildlife officials and residents of the Canadian Maritime Provinces have noted that the several herds of grey seals have been nearly decimated by a recent intense winter storm with high winds that produced high waves and blizzard conditions that occurred during an unusually mild winter which melted the ice where many of the seals would deliver their newborn pups. [USA Today]
(Thurs.) Diurnal behavior of krill could affect carbon transfer in oceans -- Scientists with the British Antarctic Survey and the University of Hull have been studying the daily vertical migration of Antarctic krill that serve as a food staple for many marine species in the Southern Ocean and conclude that these small crustaceans help sequester large amounts of carbon during their frequent nighttime descents that have the appearance of parachuting. [EurekAlert!]
(Thurs.) A hot spot in the Caribbean -- An international team of scientists have found a spot in the Caribbean Sea that exhibits almost unprecedented diversity of sea life. [BBC News]
(Thurs.) New desalination techniques unveiled -- A chemical engineer with the New Jersey Institute of Technology who is the leader of a team of researchers recently reported on the team's progress in the new membrane distillation method for desalinating water from brine with high salt concentrations. [EurekAlert!]
(Tues.) Another view of the developing La Niña event -- NASA recently released a map showing the sea surface anomalies (differences between observed and long-term average temperatures) observed from the orbiting Advanced Microwave Scanning Radiometer for EOS during the last week of January, confirming the forecast made by scientists at NOAA's Climate Prediction Center several weeks earlier. [NASA Earth Observatory]
(Tues.) Trawling effects upon seafloor ecology examined -- Marine scientists from the University of Maine, in cooperation with a trawler captain and the Gulf of Maine Research Institute, have conducted a long-term study of the possible effects that trawling for bottom fish have had on the overall ecology of the sea floor in the Gulf of Maine. [EurekAlert!]
(Tues.) A space-age portrait of a historic island -- NASA recently posted an image taken from the orbiting International Space Station of Cuba's Cayo Largo del Sur, an island reported to have been visited by Christopher Columbus on his second voyage in 1494 and Sir Francis Drake in his circumnavigation of the globe nearly one century later. [NASA]
(Tues.) Farmed salmon could threaten wild populations -- Canadian biologists report that their investigations provide scientific evidence to the claim that escaped farmed salmon could infiltrate and pose a threat to the more fit wild salmon populations. [EurekAlert!]
Gulf reef showing signs of recovery -- The manager of the NOAA Flower Garden Banks National Marine Sanctuary located off the Texas-Louisiana coast recently reported that the coral reefs in this sanctuary appear to be recovering from what some experts were fearing to be a deadly coral bleaching event last fall. [NOAA News]
Katrina's exact toll may never be known -- Officials along the Gulf coast are indicating that the exact death toll due to Hurricane Katrina may never be known exactly as many bodies may never be recovered. A recent count indicates that more than 1300 bodies have been found. [USA Today]
Another view of the 2005 Atlantic hurricane season -- The NASA Goddard Space Flight Center has posted several animated images featuring several hurricanes and tropical storms that helped make the 2005 North Atlantic hurricane season historic. These images were obtained from the NASA fleet of orbiting satellites. [NASA GSFC]
Fishing boat sounds attract sperm whales -- Scientists report that sperm whales in the Gulf of Alaska have become a nuisance as they appear to be using the characteristic sounds of fishing boats to find and feed on the coveted sablefish that are being caught on longlines. [ENN]
Volcanoes help slow warming of oceans -- Scientists at Lawrence Livermore National Laboratory, the National Center for Atmospheric Research, the University of Reading and the Hadley Centre have found that, based upon the results of a dozen climate models, ocean warming and the rise of sea level during the 20th century were reduced by major volcanic eruptions, such as the 1883 eruption of Krakatau and the 1991 Mt. Pinatubo eruption. [Lawrence Livermore National Laboratory]
Could global warming cause a deep freeze in Europe ? -- Researchers at the University of Alberta report that their study of ocean currents indicates that the recent melting of freshwater ice could be weakening the ocean currents that bring warm water to the coasts of northern Europe, which could result in a paradoxical "deep freeze" across the region. They propose several different methods to maintain the warm currents, including the deployment of more than 8000 barges to the northern ocean for the winter. [EurekAlert!]
Assessing squid fisheries health with sonar -- A scientific team from Woods Hole Oceanographic Institution, the Marine Biological Laboratory and California State University, Monterey Bay have developed and tested a new sonar method in order to locate, map and assess the population of squid eggs in the fishery off the California coast near Monterey. [Woods Hole Oceanographic Institution]
Height of Tibetan Plateau helps tell tale of colliding continents -- Geologists from the University of Chicago and Miami (OH) University report that based upon a technique involving the measurement of oxygen isotopes in rocks taken from the Tibetan Plateau, they have been able to reconstruct an elevation history of this plateau, indicating that it has been at its present elevation for at least 35 million years. Their findings would indicate a different view of changes in the Earth's crust during the collision of the plates that form India and Asia than previously held. [EurekAlert!]
Global and US Hazards/Climate Extremes -- A review and analysis of the global impacts of various weather-related events, including drought, floods, and storms during the current month. [NCDC]
Earthweek -- Diary of the Planet [earthweek.com] Requires Adobe Acrobat Reader.

Concept of the Week: Variations in Marine Sediment Thickness

Sediments are particles of organic or inorganic origin that accumulate in loose form in depositional environments such as lake or ocean bottoms. Marine sediments, the central focus of this week's investigations, have a variety of sources and exhibit a wide range of composition, size, and shape. Marine sediments settle to the ocean floor as unconsolidated accumulations but ultimately may be converted to solid sedimentary rock via compaction and cementation. The pattern of variations in marine sediment thickness on the ocean floor confirms some basic understandings regarding marine geological processes.

Go to the DataStreme Ocean Website and under "Geological," click on "Sediment Thickness." This map of marine sediment thickness in the ocean basins was compiled by the National Geophysical Data Center (NGDC), Marine Geology and Geophysics Division primarily based on existing maps, ocean drilling, and seismic reflection profiles. Sediment thickness is color-coded in meters from violet (thinnest) to red (thickest). Many factors account for the variation in the thickness of marine sediment deposits including type and location of sediment sources, sediment transport mechanisms, and the age of the underlying crust.

According to the map, sediment thickness generally increases with distance from near the central portion of an ocean basin to the continental margin. This pattern may be explained by the principal sediment source and/or the age of the underlying crust. Rivers and streams that empty into the ocean slow and diverge, releasing the bulk of their suspended sediment load in coastal environments (e.g., bays, estuaries, deltas) and onto the continental shelf. Ocean currents transport sediment along the coast. In some areas of the continental shelf, massive amounts of sediment accumulate, become unstable, and flow down the continental slope to the base of the continental rise and beyond. However, only the finer fraction of river-borne sediment is swept into the deep ocean waters. Thickening of marine sediments in the direction of the continental margin may also reflect the aging of oceanic crust with distance away from divergent (spreading) plate boundaries where new oceanic crust forms. The older the crust the longer is the period that sediment rains down on the ocean bottom and the thicker is the blanket of accumulated sediment.

The map indicates that the thickness of marine sediment deposits is greater in the continental margin along the Atlantic coast of North America than along the Pacific coast. The Atlantic coast of North America is a passive margin; that is, the continental margin is not affected significantly by tectonic processes (no plate boundary) and the principal geological processes consist of sedimentation along with erosion by ocean waves and currents. In fact, passive margins and relatively thick marine sediment deposits occur on both sides of the Atlantic. (Passive margins also occur around the Arctic Ocean and surrounding Antarctica.) On the other hand, the Pacific coast of North America is an active margin; that is, the continental margin is associated with plate boundaries and is subject to deformation by tectonic stresses. Active continental margins are relatively narrow so that sediment delivered to the coast by rivers and streams flows directly into deeper water or trenches--preventing thick accumulations of marine sediments from building in the continental margin.

Concept of the Week: Questions

The thickness of marine sediment deposits is greater in the [(continental margins)(deep-ocean basins)].
The thickness of marine sediment deposits generally is greater in [(active)(passive)] continental margins.

Historical Events

13 February 1784...Ice floes blocked the Mississippi River at New Orleans, then passed into the Gulf of Mexico. The only other time this occurred was during the "Great Arctic Outbreak" of 1899. (David Ludlum)
13 February 1969...The National Transportation Safety Board issued its "Study of Recreational Boat Accidents, Boating Safety Programs, and Preventive Recommendations". (USCG Historian's Office)
13 February 1997...Ocean swells generated by a storm well to the northwest of the Hawaiian Islands generated surf with heights to 20 feet and some sets to 25 feet along the northern shores of the islands. A professional surfer was killed by 25-foot surf at Alligator Rock on Oahu's North Shore. Lifeguards aided more than thirty people. (Accord's Weather Guide Calendar)
14 February 1779...The famous British scientific navigator, Captain James Cook, Royal Navy, was killed by natives of the Sandwich Islands on the Kona coast of what is now the state of Hawaii's Big Island. His geographic discoveries and three scientific expeditions of the Pacific made him the most famous navigator since Magellan. (Wikipedia) (Today in Science)
14 February 1840...Officers from the USS Vincennes made the first landing in Antarctica on floating ice. (Naval Historical Center)
14 February 1903...An Act of Congress (31 Stat. L., 826, 827) that created the Department of Commerce and Labor provided for the transfer of the Lighthouse Service from the Treasury Department. This allowed the Secretary of Commerce and Labor to succeed to the authority vested in the Secretary of the Treasury under the existing legislation. (USCG Historian's Office)
14 February 1912...The first diesel-powered submarine was commissioned in Groton, CT. (Wikipedia)
14 February 1954...A waterspout was observed two miles east of Baranof, AK, an unusual occurrence for Alaska, particularly in winter. Just prior to the formation of the waterspout, a "terrific wind from the south out of a bay inside Warm Springs Bay" lifted water 20 feet and looked "as if it were boiling". (Accord's Weather Guide Calendar)
15 February 1912...Fram reached latitude 78º 41' S, farthest south ever by ship. Therefore, the "Fram" became the first ship to have sailed the farthest north and the farthest south.
15 February 1954...An ocean exploration depth record of 13,287 feet (over 2,000 fathoms, or over 2-1/2 miles) was attained when Georges Houot and Pierre Willm reached the Atlantic Ocean floor off Dakar, Senegal. (Today in Science)
15 February 1982...An intense cyclone (low pressure system) off the Atlantic coast of Newfoundland capsized the Ocean Ranger, a drilling rig, killing 84 persons, and sank a Soviet freighter resulting in 33 more deaths. The cyclone produced 80-mph winds that whipped the water into waves fifty feet high. (David Ludlum)
15 February 1998...A "rogue" wave from the Pacific Ocean swept into the harbor at Port Arena, CA. This wave continued through a harbor parking lot, depositing sand, debris and logs, as well as moving thirty parked vehicles. No injuries were sustained. (Accord's Weather Guide Calendar)
16 February 1832...The HMS Beagle with Charles Darwin onboard reached St-Pauls (1ºN, 29ºW).
16 February 1993...The Haitian passenger ferry Neptune sank, sending 1,215 Haitians to their deaths. Coast Guard units participated in the search and rescue operation but found no survivors. They then assisted in recovering the bodies of the victims. (USCG Historian's Office)
17 February 1836...The HMS Beagle and Charles Darwin left Tasmania.
17 February 1867...The first ship passed through the Suez Canal. (Wikipedia)
18 February 1828...More than 100 vessels were destroyed in a storm at Gibraltar.
18 February 1846...A General order was issued by the Secretary of the US Department of Navy "on Port and Starboard," in which the term "port" replaced "larboard." (Naval Historical Center)
19 February 1473...Nicolaus Copernicus, the father of modern astronomy, was born in Torun in north central Poland. He was the first modern European scientist to propose that the Earth and other planets revolve around the Sun. (The History Channel)
19 February 1845...The Lighthouse Establishment was transferred to the Revenue Marine Bureau. Metal buoys were first put into service. They were riveted iron barrels that replaced the older wooden stave construction. (USCG Historian's Office)
19 February 1972...A vicious coastal storm dumped 10 to 20 inches of snow over interior sections of the mid-Atlantic and Northeast states and caused some of the worst coastal damage of the century in New England. Storm surges up to 4.5 ft and winds gusting over 80 mph along coastal Rhode Island, Massachusetts, New Hampshire, and Maine resulted in extensive property damage and tremendous beach erosion. Twenty-seven houses were destroyed and 3000 damaged in Massachusetts alone. (Intellicast)
19 February 1977...Using the research submersible Alvin, deep-ocean researchers John B. Corliss and John M. Elmond found an extraordinary oasis of life on the Pacific Ocean floor off the Galapagos Islands, including new types of worms, clams and crabs around geothermal hot water vents. These organisms appeared to depend upon bacteria oxidizing hydrogen sulfide contained in the volcanic gases spewing out of the hot springs. (Today in Science)