Spatio-temporal distribution, abundance and diversity of zooplankton community structure in River Shasha, Southwestern Nigeria

This study was carried-out to investigate the abundance and diversity of zooplankton in River Shasha, Southwest Nigeria. The zooplankton community constitutes an important component in the faunal composition of the water body. Samples were collected bi-monthly between February 2006 to February 2008, with a mind of capturing various seasons in the period of study, at two sampling stations (Ipetumodu and Edun-abon) established along River Shasha. A total number of 54 zooplankton species were identified, comprising five classes, namely Rotifera (29 species), Ostracoda (8 species), Arthropoda (5 species), Copepoda (5 species), Protozoa (4 species) and Cladocera (3 species). The most abundant species were Brachionus, Lecane and Keratella recorded the highest distribution among the zooplankton observed during the sampling period. Among the Rotifers, Branchions patulus and Filina opoliensis were found abundant. Holopedium amazonicum and Scapholebris armata were predominant among the Cladoceras. Among the Copepods the dominant species was Ectocyclops phaleratus and Hemicypris ovate and Cypris subglobosa among Ostracoda. Among the Protozoa, Diffugia sp and Vorticella sp were observed. Ceratopogonid sp. was most dominant among Arthropoda. The density of zooplankton population was maximum during dry season (158702 Org/L) and minimum (12402 Org/L) during rainy season due to the different environmental conditions of the water bodies. The overall mean abundance of zooplankton population was in the following order: Rotifera > Protozoa > Arthropoda > Copepoda > Cladocera >Ostracoda. The few species of Zooplankton identified in River Shasha may reflect the moderate level of limit nutrient and there is a need for regular monitoring of the waterbody to avoid the excess input of nutrients from domestic and agricultural waste that could lead to eutrophication.