Effects of Tide on Zooplankton Community of a Tributary of Upper Bonny Estuary, Niger Delta, Nigeria

Abstract. Okpoka Creek is a tidal tributary of the Upper Bonny Estuary in the Niger Delta receiving organic anthropogenic effluents from Trans-Amadi Industrial Layout and the waterfront communities. The study investigated the influence of tide (low and high) on the species composition, diversity, abundance and distribution of zooplankton. The surface water and zooplankton samples were collected monthly from May 2004 ? April 2006 at low and high tides from ten stations according to APHA methods. Zooplankton was identified microscopically. Species diversity was calculated using standard indices. Data analyses were done using analysis of variance, Duncan multiple range and descriptive statistics. Phosphate and ammonia exceeded FEPA and USEPA acceptable levels of 0.10 mg/L and 0.10 mg/L respectively for natural water bodies. Phosphate had significant tidal variations (P