excessive water abstraction upstream of Ruaha National Park has significantly reduced river flow of the Great Ruaha River during the dry season
This raises the question of how much of the biodiversity loss should actually be attributed to hippos versus human water use.
significantly lower DO and pH than low-density H. amphibius pools
The lower dissolved oxygen helps explain why high-density hippo pools can support fewer fish.
natural seasonal variation in river flow has increased drastically in duration and intensity
This makes me think the issue isn't necessarily the hippos themselves. Human changes to water flow seem to be creating conditions where their normal behavior becomes much more harmful.
H. amphibius population in the Maasai Mara National Reserve, Kenya, egested 8,563 kg dry matter/d into their diel habitats in the Mara River.
This really puts the scale of hippos impact into perspective. I wouldn't have expected one species to transfer this much material into an aquatic ecosystem every day.
large sections of the Great Ruaha River stop flowing and form discrete pools separated by large expanses of dry riverbed
When the river becomes isolated pools, hippos and their waste become concentrated in much smaller areas.
it is possible that this role reverses during no-flow periods when there is a buildup of H. amphibius organic matter.
This is interesting because hippos can go from helping an ecosystem by providing nutrients to hurting it when the river stops flowing.
reducing primary production and light penetration in the water column
The buildup of organic material can block sunlight and hurt primary producers that the rest of the food web depends on.
can have large impacts on recipient aquatic habitats,
Shows that species moving between land and water can have major effects on the ecosystems they enter.