30 Apr 2020
Kalimantan, one of the biggest islands in Indonesia, also known as an “island with thousand rivers”. Mahakam River is a famous one. Mahakam River flows from Mahakam Ulu to Makassar Strait (920 km) which makes it the second-longest river in Kalimantan. As an important element to the ecosystem, it has many unique and endemic species, one of them is Irrawaddy Dolphin.
Irrawaddy Dolphin (Orcaella brevirostris), is the only freshwater dolphin in Indonesia. The Critically Endangered species is the symbol of East Kalimantan Province and also protected by Indonesian laws. According to Rare Aquatic Species of Indonesia Foundation (YK-RASI), there are only around 83-97 of these dolphins in the wild. Approximately, 4 dolphins are dying every year, meanwhile, the birth-rate of this species is 5 dolphins per year. That is the reason why it is classified as a Critically Endangered species by the IUCN red-list.
The Mahakam River condition is also a threat to the dolphin’s life because of the human activities that increase overtimes. From the research that has been conducted since 2017, Mahakam River is polluted by heavy-metal pollutants such as cadmium (Cd) and lead (Pb) that goes beyond the quality standard, 23 times higher than the threshold.
In 2018, there was a case of the dolphin calf’s death that still nursed by its mother. After the necropsy, they found out that the cause of its death was the dangerous chemicals from the mother’s milk. It was indicated that the chemicals were coming from the human activities in the land that washed away when it was flooded. As one of the longest river in Indonesia, threats to the Mahakam River should become a concern. As Mark Angelo said, “Rivers are the arteries of our planet; they are lifelines in the truest sense.”