Gilberto Díaz

Paralytic shellfish poisoning with a Gymnodinium catenatum red tide on the Pacific Coast of Mexico

A dense red tide of the dinoflagellate, Gymnodinium catenatum, affected at least 200 km of the mainland coast of Mexico at the entrance of the Gulf of California in April, 1979, during an upwelling event. Although this organism had not previously been reported as toxic, a paralytic shellfish poisoning outbreak occurred, with three human deaths and an extensive fish kill. The organism was shown to be responsible for the toxicity and a level of about 10−12 g of saxitoxin equivalents per cell was detected. The fish kill may have been due to severe oxygen depletion of the water column.

Pollution by petroleum hydrocarbons in sediments from continental shelf of Tabasco state, Mexico

The Wider Caribbean is potentially one of the largest oil producing areas in the world. Major petroleum production areas include Louisiana and Texas, USA; the Bay of Campeche, Mexico; Lake Maracaibo, Venezuela; and Gulf of Paria, Trinidad; all of which are classified as production accident high-risk zones. About 5 million of barrels are transported every day in the Caribbean, thus generating an intense tanker traffic. It has been estimated that oil discharges from tank washings within the Wider Caribbean could be as high as 7 million barrels/year. For all those reasons petroleum pollution is considered as the major environmental problem in the Wider Caribbean area and increasing day to day due to the use of petroleum as the main energy source. On the other hand, the continental shelf of Tabasco state actually represents one of the most productive areas for crude oil in the Gulf of Mexico. Sediments were collected from this area and analyzed for hydrocarbons.

Petroleum Pollution in the Gulf of Mexico and Caribbean Sea

In 1976, IOC-UNESCO and UNEP convened a meeting in Port of Spain to analyze the marine pollution problems in the region, noting that petroleum pollution was of regionwide concern and recommended initiating a research and monitoring program to determine the severity of the problem and monitor its effects. The Wider Caribbean is potentially one of the largest oil-producing areas in the world. Major production sites include Louisiana and Texas in the U.S.; the Bay of Campeche, Mexico; Lake Maracaibo, Venezuela; and the Gulf of Paria, Trinidad. All these are classified as high-risk production accident zones. Main sources of petroleum pollution in the Wider Caribbean are production, exploitation, transportation, urban and municipal discharges, refining and chemical wastes, normal loading and unloading operations, and accidental spills. About 5 million barrels of crude oil are transported daily in the Caribbean, thus generating an intense tanker traffic. It has been estimated that oil discharges from tank washings within the Wider Caribbean could be as high as 7 million barrels/yr. The results of the Caribbean Pollution Regional Program (CARIPOL) conducted between 1980 and 1987 pointed out that significant levels of petroleum pollution exist throughout the Wider Caribbean, including serious tar contamination of windward exposed beaches, high levels of floating tar within the major current systems, and very high levels of dissolved and dispersed hydrocarbons in surface waters. Major adverse effects of this type of pollution include: high tar levels on many beaches that either prevent their recreational use or require very expensive cleanup operations, distress and death for marine life, and responses in the enzyme systems of marine organisms that have been correlated with declines in reproductive success. Finally, the presence of polycyclic aromatic hydrocarbons (PAHs) in tissues of important economic species has been reported, creating a risk for public health because of the potential carcinogenic effects.