Assessing the Impact of Urban/Industrial Activities on Benthic Communities of Two Creeks of the Upper Bonny Estuary, Niger Delta Using Univariate and Multivariate Techniques

Two creeks in the upper Bonny Estuary on Southern Nigeria, were studied. The Azuabie creek receives drainage inputs from an industrial layout and other coastal sources, while the Obufe creek runs parallel to earlier with less anthropogenic influence. The objective of this study is to assess to the impacts of urban/industrial activities on the macrofaunal benthos. Eight sites were sampled for faunal identification and enumeration. Analysis of Variance (ANOVA) tests were performed on univariate faunal indices (Shannon-Weiner, Margalef, Simpson's and Pielou) as well as individual genera. Polychaetes were found to have the highest numerical abundance, with Streblospio having the highest densities at Stn AB and AA (waste dump and abattoir areas) in Azuabie creek. Nephtys sp, Nereis sp, Lumbrinereis sp and Notomastus sp were found to be numerically high at Stns OA, OB, OC, OD and AD than AC, AB and AA. Cluster analysis and Multidimensional Scaling (MDS) ordination based on Bray-Curtis similarities of fauna discriminated the sites into two broad groups. The three polluted sites in Azuabie creek clustered together, while the less contaminated site in that creek formed one cluster with the four sites in Obufe creek. Both univariate and multivariate statistical tests led to comparable inferences.