Cause of manatees’ deaths still unclear but private study finds heavy metals

Environmental authorities have been unable to determine what has caused the death of at least 30 manatees in Tabasco, but an independent study found elevated heavy metal content in the animals’ habitat.

The manatees have died over the last two months, and all three levels of government have struggled to find the cause.

The federal environmental protection agency Profepa has worked with the National Autonomous University (UNAM), the agriculture sanitation authority Senasica, the National Water Commission (Conagua) and Mexican Institute of Water Technology (IMTA) to test the water in their habitat and samples of the dead manatees’ tissue.

The results have found no evidence that acute toxicity is behind the death of the animals. Specialists are now planning to collect tissue samples from live specimens, as well as from the lagoon beds and surrounding plant species.

Profepa theorized that a number of factors could be involved, including water temperature, the dry season, the accumulation of pollutants and stress on the animal’s food sources, making it difficult to identify a single cause.

Late last month, a manatee rescue and relocation plan was put in motion.

Meanwhile, an independent study by the Institute of Technology of Boca del Río has come up with different results: it detected heavy metal levels well above safe limits.

Ernesto Zazueta, president of the Association of Zoological Parks, Breeding Centers and Aquariums (Azcarm) said that traces of cadmium and lead were found not only in the water but in the carcasses of the dead mammals.

Cadmium levels were seven times greater than the allowed two milligrams per unit, while lead levels were 64 times greater than the acceptable 0.15 milligrams per unit.

Zazueta said the dead animals also showed indications of cerebral edema, which appears after exposure to a toxic agent.

Environment Secretary Rafael Pacchiano Alemán wrote on Twitter that he had not been notified of those test results but his department would get in touch with the researcher in charge in order to collect samples from the same sources.

Source: Univision (sp)