DATASTREME OCEAN WEEK TEN: 10-14 November 2003

• Expanded ocean research urged -- In a report entitled "Exploration of the Seas: Voyage into the Unknown" released last week, the National Research Council of the National Academy of Sciences recommended that the federal government make a major commitment to research in the oceans, to include funding a new research ship and a fleet of underwater vessels. [USA Today]
• Big wake behind the islands -- A researcher at the University of Hawaii and a colleague at NASA’s Jet Propulsion Laboratory have been studying the role that the presence of the Hawaiian Islands has upon the trade wind regime in the atmosphere and the currents in the Pacific Ocean. Using data from the SeaWinds sensor on the QuikSCAT satellite along with instruments from the TOPEX/Poseidon and Tropical Rainfall Measuring Mission (TRMM), the scientists have discovered that the wind wake extends 3000 km downwind and that it helps induce an eastward "counter current" in the Pacific that brings warm water 8000 km from the Asian coast to Hawaii. [NASA]
• Long lasting effects of the Prestige disaster foreseen -- In a recently released report, the World Wildlife Foundation (WWF) warned that the marine environment off the north coast of Spain could suffer for the next decade from the effects the oil spill resulting from the sinking of the tanker Prestige one year ago. [WWF]
• Protection of rare sea birds expanded -- Last week South Africa signed a treaty and joined four other countries for protecting several Southern Hemisphere marine birds such as albatrosses and petrels. [ENN]
• Global warming may not be all bad for all -- A spokesman for an environmental engineering company recently reported that at least one genus of Caribbean coral has expanded its range poleward in response to warmer ocean waters as had occurred between 9000 to 4000 years ago when Atlantic water temperatures were as much as 4 Celsius degrees above those at present. [Nature]
• World's wading birds rapidly disappearing -- The Wader Study Group (WSG) recently warned that populations of many species of wading birds have declined around the world because of major environmental damage to their habitat, resulting in the classification of 23 species as "globally threatened". [National Geographic News]
• Barrier island reconnected following Isabel -- The US Army Corps of Engineers has recently completed filling in the break in Hatteras Island caused by Hurricane Isabel in late September 2003, allowing reconstruction of the road that runs along North Carolina's barrier islands. [USA Today]
• Unraveling the mysteries of submarine volcanoes -- Scientists from the U.S. Geological Survey (USGS) and an international group of universities have analyzed lava samples collected using the deep-sea submersible ALVIN and hypothesize that the tops of the lava chill against cold seawater protecting the molten interior. The seawater steam also bubbles through the lava, forming large cavities within the flowing, white hot material. [EurekAlert!]
• Red sea urchins may be really old -- Scientists from Oregon State University and Lawrence Livermore National Laboratory recently reported that red sea urchins may live between one to two hundred years in the shallow coastal waters of the North Pacific, much longer than previously thought. [Oregon State University]
• 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: Life on the Ice

Life exists on and within the floating sea ice cover of polar oceans. In the Arctic, for example, sea ice provides habitat for a variety of organisms, members of an ice-specific food web that include bacteria, viruses, unicellular algae, and small invertebrates. These organisms are adapted to tolerate dramatic changes in light intensity, temperature, and salinity.

As noted in Chapter 3, dissolved salts depress the freezing point of seawater. For example, at a salinity of 33 psu, the freezing point is about –1.9 °C. In autumn as temperatures fall, ice begins forming on the ocean surface as a porous structure of interlocking ice crystals filled with a salty liquid known as brine. The brine, representing about 10% to 30% of the ice volume, occupies tiny channels and pockets between and within the ice crystals. As winter progresses, the sea ice cover solidifies; pore space decreases; and the salinity of the brine increases. As long as the temperature remains above –5 °C, the ice is riveted by tiny passages having diameters ranging from a few micrometers to several centimeters. But when the temperature drops to lower values, the connectivity of the brine pores becomes minimal and the salinity of the brine can reach values approaching 250 psu. Ice organisms have the same temperature as the ice so that their survival within ice channels and pockets hinges on adaptations that prevent the growth of ice crystals in their bodies (e.g., some organisms accumulate fatlike materials in their bodies.)

Sea ice insulates the underlying seawater from the atmosphere so that a considerable temperature gradient develops between the ice surface (where mid-winter temperatures might plunge to –35 °C or lower) and the ice/seawater interface where the temperature is the same as the seawater (perhaps –2 °C). For this reason, most of the ice biomass is concentrated within the lowermost centimeters of the ice. Beginning in spring with the return of sunlight for photosynthesis, and continuing through summer, the populations of unicellular ice algae (often forming chains and filaments) living the lowermost portion of the sea ice explode. Several hundred species of unicellular algae living in the ice are the main primary producers in the Arctic. In fact, ice algae on average account for 4% to 26% of total marine primary productivity in seasonally ice-covered Arctic waters and up to 50% or more in perennially ice-covered waters. Dissolved organic matter from the wastes of ice algae is food for ice bacteria and algae are eaten by crustaceans, rotifers (microscopic invertebrates), and turbellarians (flatworms). Tiny crustaceans (amphipods) live on the underside of the ice, feed on algae and seek shelter from predators in the brine channels. Juvenile stages of zooplankton also feed on the ice bottom community. With rising temperatures in spring, the solid ice cover breaks up into pack ice and individual floes that can transport organisms thousands of kilometers before melting and releasing their content into the ocean.

Large warm-blooded animals also live on the sea ice. Birds (e.g., penguins in the Antarctic), seals, whales, and polar bears utilize sea ice for migration routes, hunting grounds, and rookeries. Seasonal changes in ice cover and thickness makes for a dynamic environment and requires animals to have excellent navigation skills.

Polar bears have a special adaptation that enables them to survive the extreme cold of the Arctic atmosphere. Scientists became aware of the extent of this adaptation when they came up with a plan to census polar bears. Because white polar bears blend in with the snow-covered ice, scientists decided to locate and count the bears using thermal (infrared) imagery taken from an aircraft. They assumed that the polar bears would show up as hot spots on the images. However, scientists found that although they could often visually see the polar bears, the bears were not appearing on thermal imagery. Polar bear fur is so efficient as an insulating blanket that essentially no body heat was getting through the fur so that no heat signal reached the infrared sensor on the aircraft. Polar bear fur is made up of hollow tubes that function as very efficient insulators.

Concept of the Week: Questions

1. In the Arctic, most of the ice biomass occurs [(just below the surface)(at the base)] of the sea ice cover.
2. Populations of ice algae are largest in [(winter and fall)(spring and summer)].

• 10 November 1993...Violent storm over the Black Sea closed the Russian oil terminal port of Novorossisk for 20 days. "Bora" winds reported as high as 112 mph sank at least seven ships. (The Weather Doctor)
• 11 November 1099...Violent storm in the North Sea killed 100,000 people in England and The Netherlands. (The Weather Doctor)
• 12 November 1956...(date approximate) The crew on the icebreaker USCGC Glacier saw what may have been the world's largest iceberg. Observed about 150 miles west of Antarctica's Scott Island, the iceberg was about 60 mi wide by 208 mi long, or roughly the size of Maryland. (Accord Weather Calendar)
• 13 November 1970...A cyclone swept over Bangladesh, then known as East Pakistan, pushing a 49 foot storm surge against the coast at high tide. Flooding killed 500,000. Over 50 million people were affected by the storm rain, wind and surge. (The Weather Doctor)
• 14-21 November 1991...Tropical Cyclone Tia spent most of its life near the Solomon Islands and Vanuatu. However, it completely destroyed 90 percent of all dwellings on Tikopia Island. The remaining 10 percent of the buildings had collapsed walls or roofs that had been blown off. (Accord Weather Calendar)
• 15 November 1860...The light in the massive stone Minots Ledge Lighthouse, which was built on the original site of the one lost in 1851, was exhibited. Work on the new lighthouse was commenced in 1855 and finished in 1860. "It ranks, by the engineering difficulties surrounding its erection and by the skill and science shown in the details of its construction, among the chief of the great sea-rock lighthouses of the world." (USCG Historians Office)

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Prepared by AMS DSOcean Central Staff and Edward J. Hopkins, Ph.D., email hopkins@meteor.wisc.edu
© Copyright, 2003, The American Meteorological Society.