Species Composition, Taxonomic Diversity and Community Structure of the Ichthyofauna of Ikot Okubara River, a Tropical Rainforest Ecosystem in Nigeria
DOI:
https://doi.org/10.54536/ajff.v1i1.8428Keywords:
Cichlidae, Community Structure, Cross River Estuary, Ichthyofauna, Species CompositionAbstract
Baseline data on fish species composition and community structure are lacking for many small tributaries of the Cross River estuary in southern Nigeria, limiting evidence-based fisheries management. This study surveyed the ichthyofauna of the Ikot Okubara River, Akwa Ibom State, over seven consecutive months (May–November 2025) using encircling nets, cast nets, and non-return valve traps deployed with local fishers. Specimens were preserved in 10% formaldehyde and identified to species level using standard regional taxonomic keys. A total of 269 individuals belonging to 19 species, 14 genera, nine families and six orders were recorded. The assemblage was numerically dominated by the family Cichlidae (nine species; 71.7% of total occurrences), with Oreochromis niloticus alone constituting 45.4% of all individuals (N = 122) and occurring in every sampling month. Species richness was low to moderate for most other families, and eight species (42.1% of the checklist) each contributed less than 1% of total occurrences, indicating a strongly skewed, dominance-structured assemblage typical of small, human-impacted tropical rivers. These findings provide the first documented species checklist for the Ikot Okubara River and a quantitative baseline against which future change in community structure can be measured.
References
Abiaobo, N. O., Asuquo, I. E., & Aniefiok, P. G. (2019). The trophic ecology of silver catfish (Chrysichthys nigrodigitatus) from Qua Iboe River Estuary, South Eastern Nigeria. Paper presented at the FISON Ebonyi Conference.
Abiaobo, N. O., Asuquo, I. E., Ejiogu, I. N., & Umoren, J. U. (2020). Diets and trophic niches of an amphibious fish from Jaja Creek, South Eastern Nigeria. American Journal of Biology and Life Sciences, 8(2), 8–13.
Akin-Oriola, G. A. (2003). Zooplankton associations and environmental factors in Ogunpa and Ona Rivers, Nigeria. Revista de Biologia Tropical, 51(2), 391–398.
Akpan, I. I., Essien-Ibok, M. A., Abiaobo, N. O., Udosen, I. E., Asuquo, I. E., Udoinyang, E. P., & George, I. E. (2022). Biodiversity and abundance of fish species in Ekpene Ukpa River, a tributary of the Qua Iboe River estuary, Niger Delta, Nigeria. Journal of Aquatic Sciences, 37(1), 41–49.
Amarasinghe, U. S., & Welcomme, R. L. (2002). An analysis of fish species richness in natural lakes. Environmental Biology of Fishes, 65(3), 327–339.
Asuquo, I. E., & Essien-Ibok, M. A. (2019). Sex ratio, size structure and condition index in the rope fish, Erpetoichthys calabaricus (Polypteridae), from a Niger Delta flood plain, Nigeria. International Journal of Fisheries and Aquatic Studies, 7(1), 205–209.
Asuquo, I. E., & Udofia, N. P. (2025). Assessment of morphometric components of the grey mullet (Mugil cephalus) in Uta Ewa River Estuary, Southeastern Nigeria. Global Journal of Pure and Applied Sciences, 31(3), 525–536.
Ekpo, I. E., & Essien-Ibok, M. A. (2020). Condition factor and length-weight relationship of bycatch of artisanal fisheries in Qua Iboe River estuary landed at Ibeno, Niger Delta, Nigeria. African Journal of Agriculture, Technology and Environment, 9(1), 196–207.
Ekpo, I. E., Asuquo, I. E., & Abiaobo, N. O. (2016). Threatened and endangered fish species in Nigeria, a menace to biodiversity: A review. African Journal of Education, Science and Technology, 3(1), 1–16.
Ekwu, A. O., & Asuquo, I. E. (2013). The effects of climate change on aquatic resources: The Nigerian scenario. In L. Etim, J. P. Udoh, N. Etim, & A. Ekwu (Eds.), Contemporary issues in sustainable tropical agriculture (pp. 13–21). Faculty of Agriculture, University of Uyo.
Essien-Ibok, M. A., & Isemin, N. L. (2020). Fish species diversity, abundance and distribution in the major water bodies in Akwa Ibom State, Nigeria. Biodiversity International Journal, 4(2), 82–88.
Essien-Ibok, M. A., Akpan, A. W., Udo, M. T., Chude, L. A., Umoh, I. A., & Asuquo, I. E. (2010). Seasonality in the physical and chemical characteristics of Mbo River, Akwa Ibom State, Nigeria. Journal of Agriculture, Food and Environment, 6(1&2), 59–71.
Essien-Ibok, M. A., George, U. U., Ekpo, I. E., & Emah, N. M. (2024). Species composition and diversity of coastal trawled fishes landed off the coast of Qua Iboe River estuary, Ibeno, Nigeria. Asian Journal of Research in Zoology, 7(3), 91–109.
Food and Agriculture Organization of the United Nations. (2021). Species fact sheet: Oreochromis niloticus. FAO.
Froese, R., & Pauly, D. (2017). FishBase. http://www.fishbase.org
Holden, M., & Reed, W. (1972). West African freshwater fish. Longman Group Ltd.
Idodo-Umeh, G. (2005). The feeding ecology of Mochokid species in River Ase, Niger Delta, Nigeria. Tropical Freshwater Biology, 14, 71–93.
Okogwu, O. I., & Ugumba, O. A. (2011). The abundance and diversity of the fin and shell fish of mid-Cross River, southeast Nigeria. Tanzania Journal of Zoology, 89, 388–391.
Olaosebikan, B. D., & Raji, A. (1998). Field guide to Nigerian freshwater fishes. Federal College of Freshwater Fisheries Technology.
Teugels, G., Reid, G. McG., & King, R. P. (1992). Fishes of the Cross River Basin (Cameroon–Nigeria): Taxonomy, zoogeography, ecology and conservation. Annales Sciences Zoologiques, 266, 1–132.
Udo, E. J., Udo, A. E., & Inyang, E. E. (2021). Occurrence and abundance of fish species in Ikot Oku Ubara River: Implications for sustainable fisheries management. Journal of Aquatic Sciences, 36(1), 23–30.
Udo, I. U. (2012). Taxonomic composition, diversity and abundance of the ichthyofaunal assemblages of Iba-Oku Stream, Ikpa River, Nigeria. International Journal of Zoology, 8(2), 71–81.
