Researchers study widespread areas of low oxygen off northwest coast

Feb 15, 2008

A team of scientists studying the California Current – a slow-moving mass of cold water that travels south along the coast from British Columbia to Baja California – are seeing increasing areas of water off Washington and Oregon with little or no oxygen, possibly resulting in the deaths of marine animals that cannot leave the low-oxygen areas.

“We’re now seeing low oxygen levels that are much more widespread and far more intense than what has been recorded in the past,” according to William Peterson, one of the researchers and an oceanographer at the NOAA Fisheries Service’s science center in Newport, Ore.

“The fish have simply moved out of these areas and are probably doing fine elsewhere,” said Peterson. “But animals that can’t move to better waters like Dungeness crabs, sea urchins and starfish will perish.”

Peterson added that during the summer of 2006, anoxia – a complete lack of oxygen in the water – was recorded off the central Oregon coast for the first time.

In a paper published today in Science magazine, the researchers say that data going back to the 1950s show little evidence of widespread low-oxygen levels along the narrow continental shelf before about 2000. Since then conditions have begun to change.

The team conducted a submersible-based survey in the summer of 2006 and discovered no fish living along the rocky reefs that are normally healthy habitat for varieties of commercially important rockfishes. This is in contrast to similar surveys completed from 2000 through 2004 which registered abundant fish populations. In shallow areas in particular, the team found almost complete absence of bottom-dwelling organisms and a rise in bacteria that flourish under conditions of little or no oxygen.

Although the causes of these low- and no-oxygen conditions are not fully understood, it is known that low-oxygen water is associated with coastal upwelling – the process by which nutrient-rich waters are brought from deep water to the sea surface. There these nutrients fuel extraordinarily high production of tiny plants and animals off the coasts of the Pacific Northwest during summer.

Eventually, much of this plankton production dies and falls to the seafloor where it decomposes, reducing the water’s oxygen content, and causing hypoxia (low oxygen) or even anoxia (no oxygen).

Source: NOAA

Explore further: NASA sees Tropical Depression Polo winding down

add to favorites email to friend print save as pdf

Related Stories

Not just cool – it's a gas

Sep 12, 2014

In space, a new way of producing gas is being tested for steering satellites. On Earth, it is now fighting fires without harming the environment – and business insiders say it could be revolutionary.

Chip packets help make safer water in Papua New Guinea

Sep 11, 2014

University of Adelaide mechanical engineering students and staff have designed a low-cost and easily made drinking water treatment system suitable for remote communities in Papua New Guinea (PNG) – using foil chip packets ...

Recommended for you

NASA sees Tropical Depression Polo winding down

19 minutes ago

Infrared satellite imagery from NASA's Aqua satellite showed only a swirl of low-level clouds some deep clouds around Polo's weakening center on Sept. 22 as the storm weakened to a depression.

TRMM satellite tallies Hurricane Odile's heavy rainfall

1 hour ago

During the week of Sept. 15, Hurricane Odile and its weakened remnants produced heavy rainfall that caused dangerous flooding over Mexico's Baja California peninsula and southwestern United States. NASA's ...

Arctic sea ice helps remove CO2 from the atmosphere

3 hours ago

Climate change is a fact, and most of the warming is caused by human activity. The Arctic is now so warm that the extent of sea ice has decreased by about 30 pct. in summer and in winter, sea ice is getting ...

User comments : 0