Hippopotamus population hit hard by habitat destruction

A new study from Pensoft Publishers highlights the destructive impacts of human development on wild animal populations. A team of researchers from Nanjing Forestry University set out to investigate how the construction of a hydroelectric dam in Ghana affected the common hippopotamus.

“Landscape changes resulting from human activities have resulted in range restrictions and substantial reductions in population sizes of most animals,” wrote study lead author Godfred Bempah and colleagues. “The construction of hydroelectric dams has the same effect on species, but the study of their impact on semi-aquatic megafauna species is limited.” 

“We examined the response of a Hippopotamus amphibius population to the inundation of their habitat after the construction of a hydroelectric dam in Bui National Park, Ghana.”

The study revealed that the hippopotamus population in Bui National Park declined by about 70 percent following dam construction, dropping from 209 to just 64 individuals by 2021.

Bui National Park is one of the only places in Ghana where the common hippopotamus can be found. The researchers noted that these semi-aquatic animals depend on areas with sufficient grass for grazing and water for thermoregulation. 

An abundance of grasses combined with the convenience of the Black Volta River made the park a very suitable habitat for the hippopotamus. But in 2007, the Bui Dam Hydroelectricity Project was initiated in response to an ongoing energy crisis.

To investigate how the dam ultimately impacted the local hippopotamus population, the researchers conducted surveys over the course of 12 months. The study was designed to estimate the number of remaining hippos, and also to assess land cover changes in the area.

The experts determined that from 2003 to 2021, the number of hippos in Bui National Park decreased by 70 percent. The study also revealed noticeable changes in land cover after the dam construction, including a substantial decline in the grasslands that provided a home for the hippopotamus.

According to the study authors, increased water levels from the dam flooded and destroyed riparian grasses where the hippos once resided. As they left in search of more suitable habitats, some of the animals became victims of poaching.

The hippopotamus is listed as “Vulnerable” by the IUCN Red List of Threatened Species. The researchers concluded that – if the threats of habitat destruction and poaching are removed – the hippopotamus could possibly survive for the long-term with effective management strategies.

The study is published in the journal Nature Conservation.

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By Chrissy Sexton, Earth.com Editor

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