Mexico's Ixtoc 1 oil spill a distant mirror to BP disaster

MEXICO CITY — The Ixtoc 1 oil spill in Mexico's shallow Campeche Sound three decades ago serves as a distant mirror to today's BP deep-water blowout, and marine scientists are still pondering what they learned from its aftereffects.

In terms of blowouts, Ixtoc 1 was a monster — until the BP leak, the largest accidental spill in history. Some 3.3 million barrels of oil gushed over nearly 10 months, spreading an oil slick as far north as Texas, where gooey tar balls washed up on beaches.

Surprisingly, Mexican scientists say Campeche Sound itself recovered rather quickly, and a sizable shrimp industry returned to normal within two years.

Luis Soto, a deep-sea biologist, had earned his doctorate from the University of Miami a year before the June 3, 1979, blowout of Ixtoc 1 in 160 feet of water in the Campeche Sound, the shallow, oil-rich continental shelf off the Yucatán Peninsula.

Soto and other Mexican marine scientists feared the worst when they examined sea life in the sound once oil workers finally capped the blowout in March 1980.

"To be honest, because of our ignorance, we thought everything was going to die," Soto said.

The scientists didn't know what effects the warm temperatures of gulf waters, intense solar radiation and other factors from the tropical ecosystem would have on the crude oil polluting the sound.

There were political implications as well; the spill pitted a furious shrimping industry, reliant on the nutrient-rich Campeche Sound, against a powerful state oil company betting its future in offshore drilling, particularly the continental shelf in the Gulf of Mexico it began developing in the late 1970s.

In the months after Ixtoc 1 was capped, scientists trawled the waters of the sound for signs of biological distress.

"I found shrimp with tumor formations in the tissue, and crabs without the pincers. These were very serious effects," Soto said.

Another Mexican marine biologist, Leonardo Lizarraga Partida, said the evaluation team began measuring oil content in the sediment, evaluating microorganisms in the water and checking on the biomass of shrimp species.

As the studies extended into a second year, scientists noticed how fast the marine environment recovered, helped by naturally occurring microbes that feasted on the oil and degraded it.

Perhaps due to those microbes, aquatic life along the shoreline in Texas had returned to normal within three years — even as tar balls and tar mats remained along the beaches, sometimes covered by sand, according to Wes Tunnell, a marine biologist at Harte Research Institute of Gulf of Mexico Studies at Texas A&M University in Corpus Christi.

"We were really surprised," Lizarraga said. "After two years, the conditions were really almost normal."

The Gulf currents and conditions of the Ixtoc 1 spill helped. Unlike the BP blowout, which has spewed at least 5,000 barrels of oil a day, and perhaps many times that, at depths near 5,000 feet, the Ixtoc 1 oil gushed right to the surface, and currents slowly took the crude north as far as Texas, killing turtles, sea birds and other sea life.

"I measured 80 percent reduction in all combined species that were living in the intertidal zone," Tunnell said.

While that was severe, Tunnell noted natural oil that seeps from the seabed releases the equivalent of one to two supertankers of crude in the Gulf of Mexico each year.

"It's what I call a chronic spill," Tunnell said. "The good side of having all that seepage out there is that we've got a huge population of microbes, bacteria that feed on petroleum products in the water and on shore. So that helps the recovery time."