The Taxa Structure and Composition of Zooplankton Communities of Bonny Estuary: A Bio-indication of Anthropogenic Activities.

This study was aimed at ascertaining the zooplankton taxa structure and composition as a way of assessing the environmental quality of the Bonny estuary. The plankton net of 55 μm meshsize was towed vertically, preserved in welllabeled 250 ml polyethylene bottles, and fixed with 10% formalin. In all, 2,928 zooplankton specimens were collected: Calanoid copepods were the most abundant constituting 55.3% of all collections, followed by Cyclopoida (10.2%), Harpacticoida (5.8%), Copepod larvae (17.0%); Annelida/Polychaeta larvae (1.9%); Chaetognatha (2.3%); Appendicularia (2.2%); Pisces larvae (2.6%); Tunicate larvae (0.6%); Cnidaria (0.1%); Ctenophora (0.1%); Echinodermata larvae (0.9%); Mollusca larvae (1.2%); Copepoda /Cladocera (0.03%); and Malacostraca (0.1%). A total of 119 species was collected, and Margalef’s diversity index ranged from 1.54 to 7.58. There was relatively higher abundance and diversity of zooplankton in the offshore sampling stations than in the near-shore sampling stations, probably due to impacts of natural, ecological, and anthropogenic factors. Mitigation measures to significantly check these anthropogenic activities among inhabitants of near-shore areas are recommended.