Weekly Ocean News

DATASTREME OCEAN WEEK FOUR: 16-20 February 2009

Ocean in the News

Eye on the tropics -- At the start of last week, two tropical cyclones (low pressure systems originating in the tropics) weakened and dissipated over the waters of the South Indian Ocean.
Tropical Cyclone Gael, which had become a major category 4 cyclone of the Saffir-Simpson Intensity scale, weakened early in the week over the western South Indian Ocean after it had traveled southward off the coast of Madagascar and then curved toward the southeast. Satellite images and other information for Gael are on the NASA Hurricane Page.
Tropical Cyclone Freddy, which only gained tropical-storm intensity, dissipated at the start of the workweek after traveling to the southwest across the eastern South Indian Ocean. Additional information concerning Freddy can be found on the NASA Hurricane Page.
Ocean-related photos and videos available on new online media library -- The NOAA’s Office of National Marine Sanctuaries recently launched a new online multimedia library that provides the public with access to thousands of high-resolution, ocean-related photos and videos taken in all 14 marine protected areas managed by NOAA by agency scientists, educators, divers and archaeologists. [NOAA News]
Concern raised for antibiotic resistance produced by marine ecosystems -- Scientists from the NOAA Oceans and Human Health Initiative and their colleagues recently raised concern that antibiotic-resistant illnesses could potentially arise from the marine environment and affect ocean beach users. However, they did indicate that the marine environment could also provide possible cures for these threats. [NOAA News]
Another right whale is disentangled -- A coordinated rescue mission by members of NOAA's Fisheries Service along with state conservation officials from Georgia and Florida freed an endangered North Atlantic right whale from entangling ropes in waters of the Southeastern US late last week, marking the third whale disentangled in the last eight weeks. [NOAA News]
Public is advised to avoid seal pups on the beach -- Officials with NOAA’s Gulf of the Farallones National Marine Sanctuary along the central California coast recently advised the public going to the beaches along San Francisco Bay Area to avoid any newborn harbor seal pups that may be found on the beach. [NOAA News]
Fetal exposure to toxins could increase epileptic seizures -- NOAA scientists recently reported that their study of the epileptic seizure patterns in California sea lions found in the Channel Islands National Marine Sanctuary indicates that exposure to DDT and domoic acid, two environmental toxins, could explain the increase in the number and intensity of epileptic seizures in humans, especially during fetal development. [NOAA News]
Claims made that Antarctic ice sheet collapse could affect axial tilt -- Geophysicists at the University of Toronto warn that the collapse of the west Antarctic ice sheet and its ultimate melting could cause a 500-meter shift in the Earth's spin axis, thereby resulting in much higher sea levels to occur in some areas, including a migration of water into the southern Indian Ocean and toward North America from the southern Atlantic and Pacific Oceans north. [Australia's ABC News]
Dramatic rises in sea level found in the past record -- A research zoologist at the Smithsonian’s National Museum of Natural History and a geologist at North Carolina's Bald Head Island Conservancy have discovered sedimentary and fossil evidence in Bermuda that provides proof that sea level rose more than 70 feet above its current level during an interglacial period of the Middle Pleistocene approximately400,000 years ago. Apparently, this rapid rise caused widespread effects on the ecosystems of many coastal locales. [Smithsonian Newsdesk]
Penguins become long-distance commuters because of changing oceanic conditions -- A University of Washington biologist has found that changing ocean conditions have forced the Magellanic penguins living along Argentina's Atlantic coast to swim greater distances to find food than a decade ago, the result of climate change, oil pollution and overfishing by humans. [EurekAlert!]
Climate change and fisheries impacts examined -- Scientists at the United Kingdom's University of East Anglia, the Sea Around Us project at the University of British Columbia and Princeton University have provided the first calculations of the likely impact that changes in climate would have upon the distribution of more than 1000 fish species in the world oceans. They conclude that "the impact of climate change on marine biodiversity and fisheries is going to be huge." [EurekAlert!]
Deep sea nutrient mysteries revealed -- Researchers from the University of Minnesota, the University of Southern California, Lawrence Berkeley National Laboratory and the Woods Hole Oceanographic Institution have determined that iron particles can bubble up to near the surface from deep-sea hydrothermal vents on the ocean floor, thereby providing living marine organisms with this rare but necessary nutrient. [EurekAlert!]
An All-Hazards Monitor -- This Web portal provides the user information from NOAA on current environmental events that may pose as hazards such as tropical weather, marine weather, tsunamis, rip currents, Harmful Algal Blooms (HABs) and coral bleaching. [NOAAWatch]
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. Th e 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 tren ches—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

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 History)
20 February 1823...English Captain James Weddell and the brig Jane reached 74º 15' S, or 940 mi (1520 km) from the South Pole. His voyage reached farther south than anyone had ventured until the 1850s, as it was 214 mi south of the latitude that Captain James Cook had sailed.
20 February 1835...While in Chile, Charles Darwin experienced a strong earthquake and shortly thereafter saw evidence of uplift in the region. From measurements, he determined that the land rose several feet, and later hypothesized that coral reefs in the Pacific could develop along margins of subsiding landmasses. (Today in Science History)
20 February 1856...The John Rutledge, an American steamer that sailed from Liverpool, England for New York, hit an iceberg in the North Atlantic. Most of the 155 people onboard were lost.
21 February 1835...The HMS Beagle, along with Charles Darwin left Valdivia, Chile.
21 February 1907...During an exceptionally heavy gale, the British-owned mail ship Berlin hit dangerous shoals and broke up while attempting to navigate around the Hook of Holland in the English Channel. Only 14 on board survived, while 127 were killed or drowned.
22-26 February 1995...Cyclone Bobby slammed into the Western Australia coast causing widespread flooding. Some areas reported up to 12 in. of rain from the storm. (The Weather Doctor)