(Image: Jen Guyton)

Don’t just flush it away. Just as one person’s trash is another’s treasure, hippo dung seems to be a valuable source of nutrition for the animals’ aquatic neighbours.

By injecting millions of tons of faeces into African waters every year, hippos may be providing a vital link between terrestrial and aquatic ecosystems.

Douglas McCauley of the University of California in Santa Barbara and his colleagues compared fish and dragonfly larvae in two river pools in Kenya’s Laikipia district, one inhabited by hippos (see picture above) and the other hippo-free.


They found components of hippo dung in the tissues of dragonfly larvae that lived alongside the animals year round. During the dry season, fish absorbed faecal nutrients as well, while levels in dragonfly larvae increased.

The team thinks that during the wet season, high rainfall dilutes the hippos’ waste and faster-flowing rivers also wash away dung before animals can access it.

As climate change and development in east Africa continue to affect local rivers, it will be important to consider how the benefits of hippo excrement can be preserved.

Journal reference: Ecosphere, doi.org/3nv