Responses of Hippopotamus amphibius to environmental changes at Bui National Park, Ghana

Many researchers have adopted the use of indicator species to detect changes in the environment and predict future ecological modifications. Irrespective of the popularity of indicator species concept among scientists in recent times, there is less studies on the use of mega semi-aquatic mammals as indicator species, especially in Africa. This study determined the ecological role of Hippopotamus amphibius and how the mammal respond to environmental changes in an aquatic ecosystem, focusing on changes in biological diversity (fish and phytoplankton) and environmental factors (temperature, pH, dissolved oxygen, conductivity, total dissolved solids, hydrogen isotope, and oxygen isotope) by comparing pools harboring H. amphibius and pools without H. amphibius at the Bui National Park, Ghana. The results show that H. amphibius play an important ecological role by indicating high productivity in aquatic ecosystem and serving as influencers of the aquatic food web at Bui National Park. The results found significantly higher concentrations of dissolved oxygen in H. amphibius pools than pools without H. amphibius. Significantly higher diversity of fish and phytoplankton species were recorded in pools with H. amphibius. Common fish species identified during this study include, Oreohromis niloticus, Labeo coubie, Alestes dentex and Labeo senegalensis. Phytoplankton communities were dominated by Chlorophyceae (37.26%), Cyanophyceae (25.21%), and Bacillariophyceae (21.53%). The study results also showed that H. amphibius are sensitive to changes in depth of water, preferring areas with shallow pools. Managerial options for H. amphibius populations require strong support because of their socio-ecological benefits including potential ecosystem effects, increasing fishing and tourism value at the Bui National Park.