Farm Runoff Fuels Massive Algae Blooms In Gulf Of California

[hatrack]

SAN FRANCISCO – Agricultural runoff is triggering massive algae blooms that could harm marine life in the Gulf of California, one of Mexico's most important fishing regions, according to a study published Thursday.

Stanford University researchers found a direct link between fertilizer runoff from Mexico's Yaqui River Valley and sudden bursts of marine algae in the 700-mile-long gulf, also known as the Sea of Cortez, which separates the Baja California peninsula from mainland Mexico. Their study, based on an analysis of satellite photos, will be published in Thursday's issue of the journal Nature.

"We saw these really big blooms following every irrigation event in the valley," said Michael Beman, the study's lead author and a doctoral student in Stanford's Department of Geological and Environmental Sciences. "It demonstrates that certain areas of the ocean are more vulnerable to agricultural runoff than previously thought." Scientists have long believed that large-scale coastal farming produces algae blooms that can disrupt marine ecosystems at sea, but Beman said the Stanford study presents the clearest direct evidence of the phenomenon.

EDIT

The Stanford researchers suspected that algae blooms in the Gulf of California were linked to runoff from farm fields in the Yaqui River Valley, a 556,000-acre wheat-producing area that is one of Mexico's most productive farming regions. The river drains into the gulf from the mainland side. To test their hypothesis, they analyzed images taken between 1998 and 2002 from a NASA satellite that can detect phytoplankton near the sea surface. The researchers found that a massive algae bloom, covering up to 223 square miles in the gulf, was recorded within days of substantial runoff in the Yaqui River Valley. Water is released from a reservoir about four times a year to irrigate the valley's fields."

EDIT

http://www.signonsandiego.com/news/state/20050309-1317-wst-gulfofcalifornia-pollution.html

[jpak]

1. This is exactly what happens off the Louisiana coast

each spring - and it results in the formation of the so-called "Dead Zone"...