As the northern Gulf Coast ponders the long-term effects of the oil spill, attention is increasingly turning to the southwest, where 30 years ago the Ixtoc 1 well spewed millions of gallons of crude onto shorelines in Texas and Mexico.
Texas A&M University researcher Wes Tunnell discovered during recent trips to the Bay of Campeche that remnants of big spills can linger in water and on land for decades.
Many looking for insight into this summer’s spill have sought out Tunnell, who witnessed and studied the Ixtoc events of 1979.
But “I just didn’t have the answers,” he said in an interview from his office in Corpus Christi, where he is associate director of the Harte Research Institute for Gulf of Mexico Studies. “I hadn’t been back to some (areas) in 30 years, so I decided to go down and check them out.”
Like BP PLC’s Maconda well, which spewed more than 200 million gallons of oil into the Gulf of Mexico, the Ixtoc spill began with rig explosion and a failed blowout preventer.
From June 3, 1979 until a relief well was completed in March 1980, some 140 million gallons gushed from the well owned by Mexico’s state-run oil company, Petróleos Mexicanos, or Pemex.
Upon arriving at Enmedio Island in the Mexican state of Veracruz this June Tunnell quickly found hardened tar mats — essentially the same material as asphalt spread on highways — among the reefs.
“It was, I’d say, 5 to 10 percent of the size that it was 30 years ago,” Tunnell said. “But the message was, it’s still there.”
Between an inch and three inches thick — compared to the 12-15 inches of its initial thickness — the tar mats were camouflaged by hard and, in some cases, algae-covered, outer shells, Tunnell said.
When it was cracked open, however, the rock’s nature was clear.
Tunnell said he could “still see some sheen or shine of the oily material inside of it.” And, “You could smell petroleum if you put it up to your nose, which kind of surprised me after 30 years.”
Tunnell said that harm caused by the lingering tar was evident, but also seemed limited. Algae coated it and crabs were not hesitant to crawl over it. But no corals were clinging to it, and sea grasses, killed by the crude’s initial incursion, had not returned.
On a July trip, Tunnell and other scientists motored along a Yucatan mangrove forest and noticed that the shoreline stands were not as dense as they ought to be.
“Only the trained eye would know that something wasn’t quite right,” Tunnell said. “When we got in and started digging around in the ground we were able to find the tar. I don’t think there’s much of it left there, but there is some.”
Tunnell and his colleagues are awaiting test results that will determine whether the oil found there is indeed from Ixtoc. But the mangrove forest could lend insight into the fate of similar ecosystems in the northern Gulf, such as salt marshes of the Mississippi River delta, he said.
Ixtoc’s oil didn’t last long on the beaches of the western Gulf, Tunnell said. On one Texas stretch known as Big Shell Beach, Tunnell recalled that tar was a foot thick during the summer of 1979. Within three years of the spill, he said, “you could go down there and dig through that shell and you couldn’t find a thing.”
One of the few scientific surveys performed at the time involved monitoring the abundance of creatures living at water’s edge. In that work, Tunnell and two other Texas scientists counted organisms along about 140 miles of shoreline before and after Ixtoc’s oil arrived.
What they found, according to a paper presented during a 1981 oil spill conference in Washington, D.C., was that fauna in the tidal zone declined by 80 percent and tiny organisms on the nearshore sea floor were half as numerous after the oil arrived.
Among the specific findings: bean clams, the brightly colored borrowing bivalves common along Fort Morgan’s tideline, numbered only about a third of what they were in the days before contact with oil.
The scientists where aghast by their initial findings but before they could continue their study, their funding was cut off, Tunnell said. A few years later, he was able to persuade a graduate student to resume the work.
“When she resampled, the populations were back to where they were before the spill,” Tunnell said. “So in 2½ to three years, things were back to normal, which is good news.”