Weekly Ocean News

Weekly Ocean News

DATASTREME OCEAN WEEK FOUR: 17-21 February 2014

For Your Information

Astronauts capture interesting cloud patterns across South Indian Ocean -- A wide field-of-view digital photograph made by astronauts onboard the International Space Station shows trains of bow-waves and other interference patterns in the cloud deck across the southwestern Indian Ocean made by Possession Island and East Island in the Territory of the French Southern and Antarctic Lands. [NASA Earth Observatory]
Reconstructing past oceanic conditions from marine sediment cores -- If you would like information on how scientists can reconstruct past environmental conditions in the oceans from the analysis of the physical, chemical and geological data in deep-sea sediment cores, please read this week's Supplemental Information...In Greater Depth.

Ocean in the News

Eye on the tropics --- The weather across the tropical ocean basins of the Southern Hemisphere was relatively quiet last week as austral summer continued. Organized tropical cyclone (low pressure systems such as tropical storms and hurricanes that form over tropical oceans) activity was limited to the South Indian Basin. Tropical Storm Fobane toward then southwest last week. By last Friday, Fobane had weakened and dissipated approximately 800 miles to the southeast of La Reunion Island. Satellite imagery and additional information on Tropical Storm Fobane are available on the NASA Hurricane Page.
Coral reefs threatened by sunscreen chemical -- Researchers from NOAA's National Centers for Coastal Ocean Science and their colleagues in other research institutions have found that a common chemical called benzophenone-2, or BP-2 used as an additive to personal care products such as sunscreen since the 1960s can have detrimental effects on coral reef. This chemical, which is used to protect humans against ultraviolet light, appears to kill juvenile corals, causes colorful corals to bleach and can potentially increase the mutation frequency in corals. Furthermore, most municipal wastewater treatment facilities do not remove BP-2. [NOAA National Ocean Service News]
Underlying mechanism of heart failure in fish exposed to oil spills discovered -- Recently researchers from NOAA Fisheries and their colleagues from Stanford University discovered how some polycyclic aromatic hydrocarbons (PAHs) derived from petroleum products act as ion channel blockers in the heart muscle cells of young tuna, disrupting the normal cardiac function, leading to early death. These chemicals often are found in low levels of oil pollution, including oil spills. [NOAA News]
Arctic marine mammals claimed to be ecosystem sentinels -- A NOAA oceanographer who is a member of a panel of US and Canadian scientists on the health of marine mammals and indigenous people in the Arctic recently warned that the responses of marine mammals to increased temperatures and storms across the Arctic along with dramatic decreases in seasonal sea ice can provide clues as to how the ecosystem is responding to these physical drivers. [NOAA Fisheries Newsroom]
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, drought, floods, marine weather, tsunamis, rip currents, Harmful Algal Blooms (HABs) and coral bleaching. [NOAAWatch]
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

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 74 deg 15 min 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)
23 February 1802...A great snowstorm raged along the New England coast producing 48 inches of snow north of Boston and 54 inches of snow at Epping, NH. Three large (indiamen) ships from Salem were wrecked along Cape Cod by strong winds. (David Ludlum) (Intellicast)