Hippo Feces: Their Importance in African Rivers and Lakes

Written and verified by the biologist Georgelin Espinoza Medina

Last update: 21 December, 2022

All living things play an important role in the world, because by interacting with each other (and with their environment) they achieve the balance of the ecosystem. In this article, we’ll highlight these amazing semi-aquatic animals, which allow the exchange of nutrients in two different environments. Strangely enough, even hippo feces are indispensable for African environments.

Thanks to its lifestyle, the hippopotamus serves as a type of bridge when passing elements from land to rivers and lakes. Some scientists have taken a closer look at this mammal and the importance it plays in its natural environments. Find out what hippo feces contains, because although it may just seem like simple excrement, it’s actually the key to the survival of other species.

Hippos as protagonists of African ecosystems

Hippos alternate their lives between water and land. They’re herbivorous, nocturnal, and semi-aquatic animals. They consume large tons of food in a night and it’s estimated that a single specimen can ingest about 40 kilograms (88 pounds) of grass in 24 hours. They also spend the day in the water to moisten their skin and refresh themselves.

In aquatic environments, hippos explore, dive, play, court, fight each other and even give birth to their young. However, their role in these areas goes far beyond this.

Like all herbivorous animals, hippos play an important role in the flow of energy in the food webs of ecosystems. They directly acquire nutrients from the plants they eat and pass them on to the next links in the food chain.

However, these mammals don’t transfer their energy by being preyed upon (as they have few enemies), but rather thanks to the nutritional waste dumped in the lakes and rivers of Africa.

Just as hippos consume a lot of grass, they excrete a lot of feces into the lakes and rivers where they spend the day. Let’s look at the role of this type of waste in the ecosystems inhabited by these large mammals.

Why is hippo feces so important?

Hippo feces contain nutrients needed by other living things to survive and thrive in aquatic environments. A prominent element in them is silicon, but they also contain other molecules essential for life (such as carbon, nitrogen, and phosphorus).

Silicon is found in animal and plant tissues. Plants absorb this element from the soil and incorporate it into their bodies, and hippos take it from the grasses they eat.

Hippo excrement is a waste product that enriches the water. It makes available different types of essential compounds to different creatures in the environments it’s found in.

The productivity of African lakes depends to a large extent on the arrival of silicon through their tributaries. Hippos can incorporate up to 800 kilograms of silicon from plants, and carry half of this concentration into the water through their deposition.

Hippos are key players in the silicon recycling cycle. This element is valuable to organisms known as diatoms, microorganisms that play an essential role in the fixation of carbon dioxide. They’re so efficient at this task that they’re responsible for carrying out 20% of all primary productivity on the planet, an astonishing role for such small entities.

Hippo feces is also incorporated into the bodies of other organisms, including scavenging fish, crabs, algae, and certain microbes.

A cause for concern

In recent years, the population of these mammals has been in significant decline. So much so that they’re in danger of extinction, according to the International Union for Conservation of Nature (IUCN) Red List. International Union for Conservation of Nature (IUCN) Red List. Their main threats include habitat loss and poaching.

This situation affects the balance of African ecosystems that depend on these vertebrates and their feces to enrich the aquatic environment (rivers and lakes). One of the chains that would be broken in the absence of hippos is that of diatoms, which require silicon to form their organic cell wall (in the form of silicate).

Diatom depletion can cause the development and growth of oxygen-consuming algae and in turn impact the survival of other animal species.

The existence of hippos in ecosystems is vital

The chain reaction to a possible extinction of hippos will also affect humans. Different species of fish could suffer if this catastrophic scenario were to occur, including some that are consumed in these geographic areas, which would impact the food and well-being of humans in African regions that depend on fishing.

In this way, a compound that appears to be a simple and insignificant waste product (such as hippo excrement) constitutes the nutritional basis for other living beings, even conditioning humans. Moreover, it’s essential for the proper functioning of the African rivers and lakes these mammals are found in.