Distribution and Abundance of Zooplankton in Anthropogenic-Impacted Stream, Nsit-Ibom, Nigeria

Abstract

This study aimed to investigate the distribution and abundance of zooplankton in Mbiokporo stream Nsit-Ibom Local Government Area, Akwa Ibom State, Nigeria. Samples were collected and analyzed using standard methods. The result revealed that there were 9 zooplankton taxonomic groups (namely: Arachnida, Bdelloidae, Branchiopoda, Chromadorae, Euglenoidea, Hexanauplia, Insecta, Polychaeta, Tubulinea), comprising 12 species and 91 individuals. The most abundant zooplankton species was Temora longicornis with the highest number of species across all the stations 24 > 19 > 7 for station 1, station 2, and station 3 respectively. Branchiopoda had the highest number of species (4) and highest species composition (33.33%), while Hexanauplia recorded the highest individual abundance (54.95%). The relative abundance of zooplankton phyla was as follows: (Hexanauplia, 54.95 %) > (Branchiopoda, 13.19 %) > (Bdelloidae, 8.79) % > (Chromadorae, 7.69 %) > (Polychaeta and Arachnida, 5.49 % each) > (Insecta, 2.20 %) > (Tubulinea, 1.10 %) respectively. Indices of species dominance were as follows: station 1 > station 2 > station 3, with the following values 0.4349 > 0.4235 > 0.2397 each. Meanwhile, the highest species evenness was in station 3 (0.7887), followed by station 2 (0.5495), while the lowest was in station 1 (0.486). Margalef’s species diversity was slightly higher in station 1 (1.649) than in station 3 (1.618) while the lowest was in station 2 (1.456). The equitability index among stations was as follows: 3 (0.8675) > station 2 (0.6659) > station 1 (0.6292). However, this result revealed that ongoing anthropogenic activities along the stream may resulted in the deterioration of the stream thereby leading low species composition of zooplankton as observed in this study.