A small population of Hippopotamus amphibius remains in Sierra Leone and
conservation efforts may be needed to support the Hippos and their indirect benefits to fisheries
and grassland production. The hippo is a known ecosystem engineer, and a potentially
important contributor of nutrients to the river systems they inhabit supporting the food web and
local fisheries. In this study I observed hippos in the Little Scarcies River and uplands of the
Outamba-Kilimi National Park to estimate their numbers and ultimately their potential input of
nutrients into the river. Hippos forage at night in grasslands neighboring rivers, removing up to
3.62 ha of annual production, but spend most of the day submerged in the river. The group of
hippos observed in this study contained up to 12 individuals, estimated to be contributing
approximately 44 kilograms of wet matter (feces) into the river each day, liberating
approximately 8 kg of dissolved organic carbon, 1.14 kg of total nitrogen, and 0.14 kg (140 g) of
total phosphate to the Little Scarcies River. Because of these valuable nutrient contributions, as
well as other ecosystem services provided by their movements and interactions with other
species, hippopotami should be closely monitored and protected. Park management includes a
buffer zone that has been created to mitigate anthropogenic changes to hippo habitat and
ensure survival of the population, and with proper enforcement could help hippo populations.
The results of this study are presented in the context of the broader picture of hippo
conservation in Sierra Leone.