February 2015 Vol.3 No.2

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Original Research Article

Assessing the impact of precipitation on zooplankton community structure of a tropical river, Niger Delta, Nigeria

*Essien-Ibok M. A. and Ekpo I. E.

Department of Fisheries and Aquatic Environmental Management, Faculty of Agriculture, University of Uyo, P. M. B. 1017, Uyo, 520001, Akwa Ibom State, Nigeria.

^*Corresponding Author’s Email: imaobongekpo14@yahoo.com; Tel: 08096719445

Accepted February 17, 2015

Abstract

Rainfall patterns influencing abundance, diversity and species richness of zooplankton in Mbo River, Nigeria were studied for twelve months using standard analytical methods. The aim was to study rainfall patterns determining zooplankton structure as reference point for the sustainable management of the river in view of the proposed development plans for the river basin. A total of 45 species of zooplankton in eight taxonomic groups were collected as follow: Station I had a higher species richness number (25 species) than Station II (10 species) and Station III (9 species). The results showed that Crustacea was highest constituting 48% in Station I, and 30.8% and 33.3% in Stations II and III respectively. Other taxonomic groups present included Rotifera which contributed to 20.0%, 50.0% and 55.6% in Stations I, II and III, respectively; Molluscs in Station I contributed 8.0% of the species composition but was absent in Stations II and III and Protozoa which contributed 9.1% of the total zooplankton composition in Station I but was not recorded in the other two stations. The maximum diversity per station/month (2.79) was calculated for Station I in September and minimum (0.93) was observed in Station III in July. Seasonally, wet season recorded maximum value of 3.02 while dry season recorded lower values. The significant seasonal variation in zooplankton density (cells/l), diversity and richness was regulated by rainfall.

Keywords: Diversity, Niger Delta, Rainfall, Tropical river, Zooplankton