• Skip to primary navigation
  • Skip to content
  • Skip to primary sidebar

Earth Wise

A look at our changing environment.

  • Home
  • About Earth Wise
  • Where to Listen
  • Articles
  • Show Search
Hide Search
You are here: Home / Podcast / Hippo Waste And Fish

Hippo Waste And Fish

September 10, 2018 By EarthWise Leave a Comment

https://earthwiseradio.org/wp-content/uploads/2018/08/EW-09-10-18-Hippo-Pools.mp3

Agricultural and sewage pollution can cause low-oxygen conditions and fish kills in rivers. A new study published in Nature Communications reports that hippo waste can have a similar effect in Africa’s Mara River, which passes through the world renowned Maasai Mara National Reserve of Kenya and is home to more than 4,000 hippos.

Hippos spend their nights grazing in the savanna and their days wallowing in shallow pools to keep cool and escape the sun. As they wallow, they excrete waste, which depletes oxygen from the water as it decomposes. (Microbial activity also produces chemicals like ammonium and sulfide, known to be lethal to fish).

During dry periods, oxygen-poor water accumulates in hippo pools, then periodic intense rains eventually flush the water – and its slurry of toxic waste – downstream, killing fish in its path.

Over three years, the team monitored water chemistry and flow downstream from 171 hippo pools. Of the documented 55 flushing flows – defined as when rain events increased river flow to twice its normal rate – dissolved oxygen concentrations declined during 49 of the events, falling low enough to cause fish kills 13 times.

Emma Rosi is a freshwater ecologist at the Cary Institute of Ecosystem Studies.

“We’ve also observed in this system that those fish that are killed during these periodic flushing events are quickly consumed by scavengers like vultures and hyenas.”   

This study suggests that altering a river’s flow regime through dams or water withdrawals could have ecological consequences in African rivers with hippos. It also adds to our understanding of how rivers operated before populations of large animals like hippos were eliminated from much of their historical range.

**********

 

Web Links

Photo, posted February 23, 2011, courtesy of David Berkowitz via Flickr.

 

‘Hippo Pools’ from Earth Wise is a production of WAMC Northeast Public Radio.

Tagged With: africa, agriculture, consequences, ecology, ecosystem, fish, fish kills, flushing flows, grazing, hippo, hippo pools, hippo waste, history, Kenya, mara river, oxygen, rain, river, Sewage, toxic, wallowing, Waste

Reader Interactions

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Primary Sidebar

Categories

  • Agriculture
  • Air and Water
  • Climate Change
  • Economy and Policy
  • Energy
  • Health
  • Invasive Species
  • Our Environment
  • Sustainable Living
  • Technology
  • Wildlife and Habitat

Archives

WAMC Northeast Public Radio

WAMC/Northeast Public Radio is a regional public radio network serving parts of seven northeastern states (more...)

Copyright © 2019 ·

  • Home
  • About Earth Wise
  • Where to Listen
  • Articles