Fauna type and Description

Comments on the faunas and associated ecology

Fish fauna: Cichlids, Citharinids, Rivulines and Mormyrids dominate the fish fauna.

Both black and white water rivers flow into the highly productive Niger Delta, which supports an extremely rich freshwater fauna and includes the highest concentration of monotypic fish families in the world. The five monotypic fish families are; Denticipidae, Pantodontidae, Phractolaemidae Hepsetidae, and Gymnarchidae. In all the 150 freshwater fish within the ecoregion, about twenty are endemic, including several freshwater representatives of marine families. The vulnerable, near-endemic freshwater stingray (Dasyatis garouaensis) and the endangered thorny freshwater stingray (Urogymnus ukpam) live in the delta [11] (IUCN 2002). Other noteworthy aquatic biotic elements: Sixty percent of Nigeria’s mangrove forests (the third largest in the world and the largest in Africa) are found within the Niger Delta.

Aquatic Mammals:

Aquatic mammals present in the delta include the hippopotamus (Hippopotamus amphibius) and the vulnerable pygmy hippopotamus (Hexaprotodon liberiensis) [12] (Moffat & Linden 1995). The vulnerable West African manatee (Trichechus senegalensis), semi-aquatic sitatunga (Tragelaphus spekei), marsh mongoose (Atilax Paludinosus), and the spotted-necked otter (Lutra maculicollis) also inhabit the eco-region.

Aquatic Birds:

The mangrove forests of the tidal floodplain are also important for numerous water birds, including species of heron (Ardeidae), ibis (Threskiornithidae) and pelican (Pelecanidae).

Other Aquatic Fauna:

Eleven species of frogs, a variety of monitor lizards, and three turtle species also reside in the delta.

Crocodiles:

Crocodiles include the slender-snouted (Crocodylus cataphractus), Nile (C. niloticus), and the vulnerable dwarf crocodile (Osteolaemus tetraspis).

Endemic Fishes:

Among the monotypic families, the endemic denticle herring (Denticeps clupeoides, family Denticipidae) and the hingemouth (Phractolaemus ansorgii, family Phractolaemidae) have the most limited distributions. The hingemouth possesses a completely alveolated swim bladder that functions as lungs and permits the species to survive in un oxygenated waters. Pantodon buchholzi, also from a monotypic family (Pantodontidae), is capable of aerial respiration with its swim bladder and also can leap out of the water for short distances and glide.