Foreword: The Mara River in Africa, the river that runs through Tanzania and Kenya, witnesses the miraculous migration of countless lives every year.
However, in 2018, the calm was shattered, and fishermen were shocked to find a large number of bizarre schools of dead fish floating on the river's surface, seemingly stifled by some invisible force.
Scientists' investigation reveals a shocking truth that the hippos in the Mara River are behind all this, and their feces can suffocate fish to death.
So, what exactly is the magic of hippopotamus droppings?
He-hsien
As a creature in tropical Africa, the hippopotamus is a large omnivorous mammal that mainly inhabits areas with abundant aquatic weeds, such as the Mara River basin in Africa.
Hippos are huge, with adults up to 4 meters tall and weighing up to 1.3 tons, which can even make crocodiles feel terrified, and their characteristics include stubby limbs, fat bodies, wide mouths, and short tails.
Hippos are known for their huge appetites, requiring more than 95 kg of aquatic plants and 10 kg of food per day to meet the energy needs of their massive size.
Their amazing ability to swallow even an entire pot of food can easily be swallowed like a human eating melon seeds.
Hippos are also inseparable from water, they are social animals, usually a group of hippos consists of a female, and those who live alone are often adult male hippos or female hippos with cubs who have been driven out of the group.
These giant animals spend most of their day in the water and only head to nearby water meadows in the evening in search of food.
Hippos are highly skilled swimmers, able to hold their breath in the water for 5 to 10 minutes, and are able to float easily on the surface of the water, mainly due to the large amount of fat in their bodies, and staying in the water for long periods of time helps protect their skin from the sun and mosquito bites.
Hippos are mainly vegetarians and need to consume a lot of food every day to maintain the energy needs of their huge bodies. Statistics show that a hippopotamus needs to consume at least 100 kg of food per day to satisfy its appetite.
Due to living in tropical and subtropical regions, hippos often lose a lot of water due to sun exposure, so there is an urgent need for timely hydration and nutrients to ensure the proper functioning of the body.
Manure machines
The hippopotamus eats so much in a day that it has been given the figurative title of the "Diarrhea Machine", an animal that rolls freely in the mud and has no regard for its personal hygiene.
During the same unhygienic bowel movements, they also use their tails to scatter feces around. According to statistics, an adult hippopotamus excretes more than 30 kilograms of feces per day, which is indeed worthy of their huge size.
Hippopotamus droppings often end up in rivers, which can be a bit uncomfortable for humans, yet in nature, hippopotamus excrement is irreplaceably important.
The hippopotamus' excrement is known as an eco-exchange pump, which is rich in trace elements and drifts along the river, providing natural nutrients for aquatic life.
Johns, a biologist at the University of Antwerp in Belgium, said that hippos' droppings play an important role in connecting land and lake rivers.
However, because of the large amount of hippopotamus droppings in the environment, the Mara River is subjected to a very large load every day.
A team of researchers from Yale University conducted a survey on the effects of hippo droppings and found that whenever the river is washed out during the rainy season, the droppings in the hippo ponds are washed out, which in turn negatively affects water quality.
This flushed hippopotamus droppings can cause a lack of oxygen in the water, which in turn causes bacteria in the water to consume a lot of oxygen in the water, and these bacteria also produce chemicals that are potentially toxic to fish.
Therefore, whenever there is a continuous strong current erosion of the river, the hippopotamus droppings will further deteriorate the water quality, and eventually lead to the mass death of fish.
There have been several such incidents in the records of the Mara River, with several hypoxic events that eventually led to the death of large numbers of fish.
Every year, thousands of fish die from hippopotamus droppings, and the most affected are tilapia, which, no matter how strong they are, cannot escape the "killing" of hippopotamus droppings.
In addition, a study showed that during the dry season, the biodiversity of the Mara River's pools decreased by 41 per cent, which had a negative impact on the local population for the tribe where tilapia is a staple food.
How hippopotamus manure causes the death of fish
The Mara River is an important river in the Ruaha National Park in central Tanzania and is also a haven for hippos and other aquatic life. The water is abundant, the crocodiles in the water bask in the sun, and the hippos swim in the clear water, enjoying the coolness and freedom.
Hippos are the protagonists here, however, this environmental problem caused by hippopotamal waste is also a problem for other creatures.
The bacteria in hippopotamus feces perform anaerobic respiration in the water, which causes the feces to break down quickly and consume large amounts of oxygen, which not only causes the oxygen levels to drop, but also releases large amounts of carbon dioxide and hydrogen sulfide, both organic matter and toxic gases, which have an impact on the fish population.
High concentrations of hydrogen sulfide and ammonia can affect the respiration of fish, causing them to feel breathing difficulties and even die, in addition to hippopotamus feces can also change the chemical properties of the water body, increase the ammonia nitrogen and nitrate content in the water body, and cause eutrophication of the water body.
The root cause of fish kills
The issue of fish mortality in the Mara River basin has attracted widespread attention, and human activities have played a key role in this.
Over the past few years, increasing disturbances in agriculture, forests and climate have exacerbated the potential for risks to the Mara River ecosystem, especially those related to water constraints.
In the ecosystem of the Mara River, hippos play an important role in balancing the ecosystem, and in the past, hippos coexisted with local fish, and their presence enriched and diversified the river's ecology. However, human activity is upsetting this balance.
Rapid development of agriculture has led to a surge in water consumption, and large amounts of water to irrigate farmland have led to a drop in river water levels, threatening the habitat of fish and other organisms.
Widespread deforestation also has a negative impact on ecology, with the reduction of forest cover causing changes in the water cycle, which in turn further affects river ecosystems.
However, the impact of environmental change on the problem cannot be ignored, as global warming has led to less rainfall and more water scarcity in Africa, increasing the pressure on river organisms and further exacerbating the problem of fish death.
Human activities are a major contributor to fish mortality, and it is essential to be aware of this and take appropriate solutions, starting with better forest protection, reducing large-scale deforestation and reclamation, while improving water management, reducing waste, and ensuring the continuous flow of rivers.
In tackling this problem, we must recognize the impact of human activities on the environment and take practical and effective measures to protect the health of river ecosystems.
Only by paying attention to and solving this problem can we build a more harmonious and sustainable ecological environment.
The author thinks
Hippos' droppings may smell like they want to escape, but from an ecological point of view, their defecation behavior is crucial to the ecological balance on the continent. However, the negative effects of hippopotamus feces cannot be ignored.
Perhaps, we can research and develop a technology that can effectively process hippo droppings, breaking down the harmful substances in them or converting them into kinder forms to reduce the impact on water quality and other species.
Alternatively, we can borrow from existing methods, such as introducing other organisms to help clean up hippopotamus droppings, to bring out the balance mechanism of nature.