Hippos leave fish in deep do-do

  Last updated May 31, 2018 at 1:04 pm

Topics:  

Hippo dung is so potent it can clean out a river, research finds.


Photo: Paulmaz (GFDL)


As if there weren’t already enough self-evident reasons why sharing a river with a mob of hippos is a bad idea, there’s now an extra one – which is very bad news indeed if you happen to have no other option.


A study published in the journal Nature Communications reports that hippos wallowing in Africa’s Mara River fill it with so much poo that they periodically kill fish downstream.


Researchers led by ecologist Christopher Dutton from Yale University in the US studied the environmental consequences arising from the eating and resting habits of some 4000 hippos which call the river home. The Mara stretches across Tanzania and Kenya and flows through the Maasai Mara National Reserve, where most of the hippos live.


Well adapted to the climate of Africa, hippos tend to spend their nights grazing on land, and their days hanging about in the river, escaping the worst of the heat. Relaxing all day in water after several hours of eating, however, brings inevitable consequences.


Hippos, don’t forget, are big – very big – and vegetarian to boot.


“Together, the Mara’s resident hippos add about 8500 kilograms – or 9.3 tonnes – of partially digested plant material into the river each day,” said co-author Emma Rosi. “We were interested in how this massive influx of organic matter and nutrients influenced aquatic life.”


The answer, it turned out, was severely, and unpleasantly.


During the hotter months of the year, water in the Mara evaporates, interrupting the flow and leaving the hippos happily lounging in isolated pools – to which, of course, nine tonnes of poo are added every day.


Then things get a bit toxic


The water thus quickly fouls. The plant matter in the waste decomposes, removing oxygen from the water. Associated microbial activity produces significant quantities of toxic chemicals, such as ammonia and sulfide.


Eventually, and inevitably, rain falls, the river refills, and the fetid contents of the hippo pools are flushed downstream.


Dutton and colleagues spent three years monitoring the chemistry and flow dynamics of 171 hippo pools. Through that time they recorded 55 flushing events – during which the river flowed at twice its normal rate. In 49 of the events the oxygen levels in the water downstream dropped – low enough on 13 occasions to kill fish.


“In the Mara River system, flushing flows are important for cleaning hippo waste out of pools, but the accumulated toxic chemicals and deoxygenated water have severe impacts on aquatic life downstream,” said co-author David Post.


Understanding how this happened took considerable ingenuity. Because – as multiple sources testify – getting into the water alongside hippo herds carries with it a very high risk of injury or death, the researchers measured the water chemistry in the wallows using a remote-controlled boat. They also constructed a miniature model habitat by means of incrementally dumping hippo poo into a bathtub.


They concluded that two related phenomena contributed to the fish kills. First, the deoxygenated water flushed from the hippo pools lowers the oxygen levels of water downstream. Secondly, microbial activity occurring in the excreted organic mass continues as it floats along, further chewing up oxygen.


The scientists note, however, that while periodic poo-driven fish massacres might seem like a bad thing, the events resulted in large amounts of free food for scavengers, including crocodiles and several species of bird.


Related


Ancient bird poo? Tell me moa!


Fish confused by too much carbon dioxide




About the Author

Andrew Masterson
Andrew Masterson is editor of Cosmos.

Published By

Science and technology is as much a part of our cultural fabric as art, music, theatre and literature. They play a significant role in our daily lives, yet, in a world dependent on science, we often take them for granted. Australia’s Science Channel believes every citizen has a right, and a responsibility, to be informed, and our mission is to create programs to bring that about.


Featured Videos

Placeholder
Alan Duffy on what it took to get humans to the Moon
Placeholder
Do aliens exist? Brian Cox explains
Placeholder
From Apollo to Pulsars: Parkes still dishing out the discoveries
Placeholder
Brian Cox on black holes
Placeholder
Australia's 60,000 years of space history
Placeholder
In Class With… Jane Goodall
Placeholder
Etienne Rastoin-Laplane - What's fishy about the Galapagos?
Placeholder
Kit Prendergast - Flowers to keep native bees buzzing
Placeholder
Rebecca Wellard - Eavesdropping on killer whales
Placeholder
Hossein Tavassoli - Mending broken hearts
Placeholder
Dilan Seckiner - Forensic gait analysis
Placeholder
Samuel Bladwell - A new spin on electronics
Placeholder
Sathana Dushyanthen - The double-edged cancer sword
Placeholder
Dwan Price - Nuts and Guts
Placeholder
Catriona Nguyen-Robertson - Exercise takes your immune system for a ride
Placeholder
Thimo Ruethers - The deadly danger of crocs on a plate
Placeholder
Amanda Tauber - Slamming the brakes on metastatic cancer
Placeholder
Hayley Teasdale – The ball that prevents falls (FameLab Australia 2019 Runner-up)
Placeholder
In the Shadow of a Black Hole
Placeholder
In Class With... Monica Gagliano
Placeholder
In Class With... Brian Cox
Placeholder
Start your FameLab 2019 journey now
Placeholder
Nural Cokcetin - It all starts with FameLab
Placeholder
Erinn Fagan-Jeffries - It all starts with FameLab
Placeholder
Ronald Yu - It all starts with FameLab
Placeholder
Noushin Nasiri - It all starts with FameLab
Placeholder
Grassroots
Placeholder
What is machine learning?
Placeholder
Mythbusting artificial intelligence with expert Anton van den Hengel
Placeholder
Using machine learning to predict medical outcomes
Placeholder
KCLOC
Placeholder
Nature Calls
Placeholder
Mexican Fishing Bats
Placeholder
Bittersweet
Placeholder
Timelapse
Placeholder
Invisible Blanket
Placeholder
Look
Placeholder
The Anomalies: Venom Race
Placeholder
Science Meets Making
Placeholder
Spiral
Placeholder
Looking Out There
Placeholder
Protectors of the Penguins
Placeholder
Astroturf
Placeholder
Virtual Humans
Placeholder
Rancheros del Jaguar
Placeholder
Searching For Dark Matter
Placeholder
Finding prehistoric mega-shark fossils on Victoria's coast
Placeholder
The Grandfather of computers
Placeholder
James Cameron talks science
Placeholder
In Class With.....David Suzuki - The Environment
Placeholder
In Class With.....David Suzuki - Career
Placeholder
Sustainable water use with Doug Green
Placeholder
Why is Indigenous science important?
Placeholder
Vanessa Pirotta - Using drones to collect whale snot (FameLab Australia 2018 Winner)
Placeholder
Toby Hendy - Poking Plants (FameLab Australia 2018 Runner-Up)
Placeholder
Muthu Vignesh Vellayappan - Groovy Patches (FameLab Australia 2018 Audience Choice)
Placeholder
Taryn Laubenstein - The Tail of Two Fishes
Placeholder
Richard Charlesworth - Coeliac disease diagnosis can be a pain in the posterior
Placeholder
Pegah Maasoumi - Solar Windows
Placeholder
James Wong - Breathing while you hop: How do kangaroos do it?
Placeholder
Ben McAllister - The ORGAN Experiment: Shining a light on dark matter
Placeholder
Mortaza Rezae - Empowering beautiful minds
Placeholder
Zane Stromberga - Can allergy drugs beat bladder disease?
Placeholder
Working In.....Art - Astrophotography
Placeholder
What's the best way to move - springs or muscles?
Placeholder
FameLab Australia Semi-Final Highlights
Placeholder
Saving lives with platypus milk
Placeholder
Australian astronomers witness death throes of a cocooned star
Placeholder
How Australia's politicians see our future in space
Placeholder
Keeping satellites in the loop
Placeholder
Tim Flannery talks about COP
Placeholder
Tim Jarvis & Tim Flannery talk Climate Change
Placeholder
Andy's Week in Science - robo baby, university rankings, and cancer on circadian rhythms
Placeholder
From chocolate factory to surgery - the milliDelta robot
Placeholder
Andy's Week in Science: video games, low tech transition windows and a new CRISPR technique
Placeholder
Science lessons useful in Art Restoration career
Placeholder
Are drones the future of racing?
Placeholder
The future of esports according to the experts
Placeholder
Seeing is believing with artist Eugenie Lee
Placeholder
The human impact of Art Science collaboration
Placeholder
Follow your Interests in Robotics
Placeholder
Zoz on 3D Printing
Placeholder
Flavia Tata Nardini on women in engineering
Placeholder
Flavia Tata Nardini on the future of the internet
Placeholder
Explore the ocean floor and Antarctic biodiversity
Placeholder
Follow your interests in Medical Research
Placeholder
Artists on Science
Placeholder
What is Space Archaeology?
Placeholder
Follow your Interests
Placeholder
Scientists on Art
Placeholder
3D Printing in Medical Research
Placeholder
Ethical Issues
Placeholder
Problem Solving - Robotics at Dermatec
Placeholder
Problem Solving with CSI
Placeholder
Tamarah King - Earthquake Geologist
Placeholder
True or False with Bajo and Rad BONUS ROUND
Placeholder
True or False with Bajo & Rad
Placeholder
Andy's Week in Science - Cats vs Dogs
Placeholder
FameLab 2018 - Get Involved!
Placeholder
Nural Cokcetin - How FameLab changed my life
Placeholder
Erinn Fagan-Jeffries - How FameLab changed my life
Placeholder
Noushin Nasiri - How FameLab changed my life
Placeholder
Ronald Yu - How FameLab changed my life
Placeholder
Alan Duffy's Top 5 Science Communication Tips
Placeholder
A Judge's Top Tips for FameLab Australia
Placeholder
Brain Candy - Why, Why, Why Michael Stevens?
Placeholder
The Past, Present, and Future of Malaria
Placeholder
This is a video of poo pills being made!
Placeholder
Mind Games - Sports Psychology
Placeholder
Fuel to Win - Sports Nutrition
Placeholder
Fifty years since Australia beat the world to space
Placeholder
ECR Network: Talk Your Science with Alan Duffy
Placeholder
Andy's Week in Science - chimps, klompen, and clouds
Placeholder
Our robot medicine future - heart huggers and micro biohybrids
Placeholder
Six Awkward Cancer Questions
Placeholder
How do you tell if a whale is left-handed?
Placeholder
She Flies - Turning Girls into Drone Pilots
Placeholder
Andy's Week in Science - Magnetic Fabric, Cancer Treatments, and Echolocation
Placeholder
The Science of Sexuality
Placeholder
Sailing Through Space with Bill Nye
Placeholder
Using Sports Science to Help Olympic Athletes
Placeholder
Three and a Half Minutes of Top Shelf Career Advice
Placeholder
New Space Tech with Andrea Boyd
Placeholder
Kelly Meets the Mars Curiosity Rover
Placeholder
Hearts, Opera, and Tough Conversations - Andy's Week in Science
Placeholder
Bill Nye on Science, Girls, and Saving the World!
Placeholder
2017 Prime Minister's Prizes for Science Part 2
Placeholder
2017 Prime Minister's Prizes for Science Part 1
Placeholder
Who Decides the Law in Space?
Placeholder
Scientists Watch Collision That Created Gravitational Waves
Placeholder
Getting Cold Feet Leads to a Whole New Career
Placeholder
ECR Network - Why Every Scientist Should Be on Twitter - The Benefits
Placeholder
ECR Network - Why Every Scientist Should Be On Twitter - The Fears
Placeholder
Live Podcast - Life Vs Science
Placeholder
Origami Robots, Babies, and Kidneys - Andy's Week in Science
Placeholder
Namira Salim and the Zero-G Peace Summit
Placeholder
Elon Musk's Mars Plan: Expert Analysis
Placeholder
SPACE AF - Thursday
Placeholder
My Time in Space
Placeholder
IAC TV Daily Broadcast - Wednesday
Placeholder
SPACE AF - Wednesday
Placeholder
IAC TV Daily broadcast - Tuesday
Placeholder
SPACE AF - Tuesday
Placeholder
IAC TV daily broadcast - Monday
01:00:41
Placeholder
SPACE AF - Monday
Placeholder
Live from IAC 2017
Placeholder
Brew Ha Ha - Technology Rewrites History
Placeholder
Methamphetamine - Gateway Drug to Parkinson's Disease
Placeholder
Concussion, 3D BioPrinting, and The Universe - Andy's Week in Science
Placeholder
Pulsars, Clearwigs, and Pacemakers - Andy's Week in Science
Placeholder
Revolutions - The Quest to Transform HPV Racing
Placeholder
Brew Ha Ha - Hurricane Irma Blows Away Tesla's Rip Off
Placeholder
Brew Ha Ha - The Limit of Your Lifespan
Placeholder
The Recipient
Placeholder
Think Like a Scientist: Natural Selection in an Outbreak
Placeholder
The End of Snow
Placeholder
The Next Rembrandt
Placeholder
The Discarded
Placeholder
The Spectators
Placeholder
Test Tube Babes
Placeholder
Pangolins in Peril- A Story of Rare Scales
Placeholder
Rock Art Project
Placeholder
Pork.0
Placeholder
OWSIA (Darkened Water)
Placeholder
Nex
Placeholder
Northern Quolls
Placeholder
Dish Life
Placeholder
At Street Level
Placeholder
Custom Love
Placeholder
Adrift
Placeholder
A Story from Space
Placeholder
Brew Ha Ha - The Most Dangerous Thing in Boxing May Be the Gloves
Placeholder
ECR Network 2017 – Get Interdisciplinary!
01:27:00
Placeholder
Chris Hadfield: The Future of Space Exploration
Placeholder
Chris Hadfield: Life After Space
Placeholder
Chris Hadfield: Life in Space
Placeholder
Brew Ha Ha - Let's Make Algae Australian of the Year
Placeholder
Brew Ha Ha - Australia's Energy Showdown
Placeholder
Nine Awkward Astrophysicist Questions
Placeholder
Brew Ha Ha - There's No Such Thing as an Exercise Pill
Placeholder
National Science Week Awards Show
Placeholder
Brew Ha Ha - Your 5 Step Asteroid Success Plan
Placeholder
National Science Week Forecast
Placeholder
Open Doors. Open Future. Open Day.
Placeholder
Brew Ha Ha - Lose a Little to Gain Millions
Placeholder
Brew Ha Ha - Crowd Sourcing Origami Astronaut Protection
Placeholder
Brew Ha Ha - T-Rex's Prehistoric Power Walk
Placeholder
True or False with Kale Brock
Placeholder
The Grandfather Paradox
Placeholder
Brew Ha Ha - The Hidden Heroes Tackling Mozzies
Placeholder
Brew Ha Ha - Emergency AI Assistance
Placeholder
Brew Ha Ha - Frogs Forever, Dinosaurs Never!
Placeholder
Brew Ha Ha - Australia, Let's Go To Space
Placeholder
Brew Ha Ha - Welcome to the Microbiome, Archaea!
Placeholder
Brew Ha Ha - Roos Blindside Driverless Cars
Placeholder
Biodiversity of Antarctica Under Threat From Increase In Ice-Free Areas
Placeholder
Brew Ha Ha - The Future of the Census
Placeholder
Tell Me! Brian Cox
Placeholder
Crash, Burn, Tweak, Repeat
Placeholder
Brew Ha Ha - Humans Just Got Older and Wiser
Placeholder
Brew Ha Ha - Cheers to Brain Health?
Placeholder
Gene Therapy Could Cure Allergies
Placeholder
Brew Ha Ha - iHeart Hacking
Placeholder
Ridiculology - New Hubble
Placeholder
Brew Ha Ha - Trees Alone Can't Save Us
Placeholder
Brew Ha Ha - Earth's Accidental Force Field
Placeholder
Dinosaurs on the Big Screen
Placeholder
Brew Ha Ha - Farewell MP3
Placeholder
Kids Beat Grown-ups on Pneumonia Vaccines
Placeholder
Brew Ha Ha - The Booger Conspiracy
Placeholder
FameLab 2017 National Final - Part 2
Placeholder
FameLab 2017 National Final - Part 1
Placeholder
2017 Budget Response
Placeholder
What Are Animal Weapons?
Placeholder
If You Love Both Art and Science, Be a Scientific Illustrator
Placeholder
Getting Personal With Skinks
Placeholder
Brew Ha Ha - CSIRO Email Leaks
Placeholder
FameLab 2017 Western Australia Semi-Final Highlights
Placeholder
Brew Ha Ha - New Hope for Premmies
Placeholder
Brew Ha Ha - Britain Goes Coal-Free
Placeholder
Brew Ha Ha - Naked Mole-Rats (SFW)
Placeholder
Brew Ha Ha - Easter Reminders
Placeholder
Meet Andrea Boyd - Space Flight Controller
Placeholder
Brew Ha Ha - Sperm Drug Smugglers
Placeholder
FameLab 2017 New South Wales Semi-Final Highlights
Placeholder
The Science of Fiction
Placeholder
Brew Ha Ha - Liquorice Poisoning
Placeholder
Brew Ha Ha - Crowdsourcing Science
Placeholder
FameLab 2017 Queensland Semi-Final Highlights
Placeholder
Brew Ha Ha - SpaceX Preps for Relaunch
Placeholder
Poly Cystic Ovary Syndrome Breakthrough
Placeholder
Brew Ha Ha - Surviving a Media Storm
Placeholder
Will This Aussie Team Win the Race to Create the Ultimate Malaria Vaccine?
Placeholder
Brew Ha Ha - New Dino Family Tree
Placeholder
How to fix things with Kyle Wiens
Placeholder
Repair or replace? iFixit co-founder Kyle Wiens
Placeholder
Special Investigation - No Alternative to Cancer
Placeholder
Brew Ha Ha - Raspberry Pi is Number 3 Best-Selling Computer
Placeholder
If reefs can't adapt, are they doomed?
Placeholder
Art, Music, Science, Society - Sir Tim Smit Has Thoughts On It All
Placeholder
Assembling the Best Team (according to Sir Tim Smit)
Placeholder
What's up with the Rogue Ginger?
Placeholder
Make Me A Martian
Placeholder
Brew Ha Ha - Recognising the Ethical Dilemma in Facial Tracking Software
Placeholder
Science Communication Around the Globe
Placeholder
Brew Ha Ha - Elon to the Rescue
Placeholder
Sing Us a Song, Spaceman!
Placeholder
Feather Map Of Australia Citizen Science Project
Placeholder
Tim Jarvis vs Mountain: Neuroscience
Placeholder
Brew Ha Ha - Don't Pee in the Pool!
Placeholder
Brew Ha Ha - A New Organ That's as Old as You Are
Placeholder
Brew Ha Ha - Australia's Bill of Sexual Health
Placeholder
Budget 2016 - The Science Forecast