Expedition I Statement

The purpose of this expedition was to determine the presence or remnants of Ixtoc I oil/tar mats that we first documented by our team in October 1979. Tropical storms in September 1979 pushed oil towards the Veracruz Reef System, but it appeared that the oil went over the reefs on the elevated storm surge and landed on the beaches of the reef islands. Our long-term coral reef ecology study site called Enmedio Reef and Island (from the early 1970s to mid 1990s), looked like a white sandy key with a black donut wrapped round it in October 1979. These "mousse mats", later termed "tar mats", were most widespread on the windward side of the island and averaged 2-12 inches thick and 10-30 feet in width. They were intermittently present on the leeward side also. Large numbers of a bivalve clam (Asaphis deflorata) shells and the tests of three species of sea urchins (Lytechinus variegatus, Tripneustes ventricosus, and Echinometra lucunter) were observed on island beaches.

Over the years when my Coral Reef Ecology class field trip from Texas A&M University-Corpus Christi would visit the island for two weeks each June, I would resurvey the mats and found that they continued to degrade or weather through time. Within several years they were covered by a veneer of sand and shells and were difficult to distinguish from the natural reef lagoon coral rock or rubble bottom, unless you knew where to look. Where the mousse settled in the sea grass beds (turtle grass) near the island during September 1979, the sea grass had died by the time of our next visit in June 1980.

On 16 June 2010 I returned to Enmedio to see if I could find the tar mats again. With assistance on logistics from my long-time friend and colleague Dr./Admiral Alberto Vazquez (PhD in Physical Oceanography from Texas A&M and formerly of the Mexican Navy Oceanographic Institute, as well as HRI Advisory Board Member) from Veracruz, and documentation by Joel Bourne, a writer for National Geographic, we located the first tar mat within about five minutes in the leeward lagoon. Capitan Serrano, owner of the dive shop in Anton Lizardo, the fishing village just shoreward of Enmedio, beached his panga just a few feet away from the mat and that made our snorkeling task easy.

So, after 30 years, the tar mats are still there. They appear to only be only 5-10% of the original size, and only 1-3 inches in thickness, but they are still there. When broken open, they still smell strongly of petroleum. Sand, shell, and coral are found on top and within the mats, and some algae was observed growing on top of the mat (Padina sp. and some blue green filamentous algae).

We located one other mat on the southern side of the pier on the leeward side of the island. It was more weathered, as we expected, being on the higher energy side of the island where physical processes speed the weathering process.

The next day Alberto assisted us in interviews on the beach in Anton Lizardo with some older fishermen who were active 30 years ago during the spill. They remembered it visibly as a very disruptive time for their artisanal fishing activities. They related that they had to put plastic bags on their legs to walk along the beach and to their boats in the one-foot deep oil/mousse. Look for more information on these interviews in Joel’s story in the October issue of National Geographic.