Benthic foraminifera as pollution indicator in the Bonny estuary, Niger delta.

Abstract

A seasonal study of the diversity of benthic foraminifera in the Bonny estuary was carried out at ten Stations located at various zones in the estuary. Four diversity indices, species number[S], Fisher & shannon Wiener function H(S) Equitability (E) were employed in the analysis. Examination of the spatial distribution and seasonal variations of these indices provided information on the responses of the foraminiferal fauna pollution. Diversity indices, S& and H(s) were found to be consistently low at station 5 (NNPC Refinery jetty Okrika). The dominance of pollution – tolerant species such as Ammotium salsum, Miliammina fusca and Ammonia beccarii at this station was also observed. The loe diversity indices recorded at station 5 is attributed to the fact that, it is a stressed environment resulting from pollution due to refinery effluent and oil wastes from marine tankers. Some cosmopolitan environmental indicator species identified in the study area, which could be used for subsequent monitoring studies, include: Arenoparrella mexicana, Miliammina fusca, Haplophragmoides subinvolutum, Ammotium salsum, Elphidium gunteri, Ammonia beccarii parkinsoniana and Ammonia beccarii tepida.