Cambodia – The Mekong River pollution threatens the Irrawaddy dolphins. Water pollution prevents their immune system to effectively fight against bacteria.

In 5 years, the population of Irrawaddy dolphins (Orcaella brevirostris), which evolves on 190 km of the Mekong River between Laos and Cambodia, has declined at an alarming rate. Eighty-eight died, mostly young, aged only a few weeks.

Autopsies revealed that the bacterium Aeromonas hydrophilia is the origin of these deaths. The report of Dr. Verne Dove, veterinarian for the WWF Cambodia, said that the dolphin immune system, weakened by water pollution, is not always able to resist the bacteria.

After analyzing the dead dolphins, scientists have detected high levels of pesticides like DDT, and environmental pollutants, including PCBs. Traces of mercury have been identified on some of the bodies. The product of mining activities immediately alters the immune system which becomes weakened when facing the threat of infection.

Such pollutants are harmful for the animals which live in Mekong, but they also represent a risk for the men who populate its shores and nourish products of the river.

This pollution threatens many populations settled along the banks of the river that runs through several countries in Asia. WWF Cambodia is currently the source of pollutants in the Mekong River.

In addition, consanguinity reduces the diversity of the immune defenses of Irrawaddy dolphins. This weakness, added to their geographical insulation, are two factors which make essential for the human assistance. Seng Teak, WWF Director of Cambodia, is optimistic: he points out that once their natural habitat is protected, cetaceans are particularly resistant.

The director of WWF Cambodia draws the alarm, pointing out that it is urgent to establish a cross-border program to limit pollution of river. Now the priority is to protect these dolphins, classified on the red list of IUCN as a critically endangered.