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
