Oceanographic in situ data collected in the Gulf of Guinea during six cruises carried out between 2005 and 2007 were analysed to study the influence of equatorial upwelling on the productivity of the region. At 10°W, observations during boreal summer and autumn cruises captured seasonal upwelling influences. In response to the shoaling pycnocline in June 2005, higher concentrations of nitrate and chlorophyll fluorescence were recorded at the ocean surface in June than in September. Our findings challenge the paradigm that westward advection from the nutrient-rich African coast is responsible for equatorial enrichment in the Gulf of Guinea. Vertical sections of the parameters under study in the summer of 2005 showed no westward advection from 3°E to 10°W within the equatorial band. This emphasizes the important role of vertical processes in equatorial enrichment at 10°W. An additional aspect of our study provides evidence of the impact on nutrient and chlorophyll distribution of offequatorial westward recirculation of equatorial undercurrent waters (observed between 2°and 3°S).

A five-month study in 2001 of an enclosed lagoon, Kuramo Water in southern Nigeria, exposed to urban perturbation describes its physical, chemical and macrobenthic invertebrate characteristics. Of the 16 physical and chemical conditions studied at four sites within the bank-root biotope, only BOD and TDS content were significantly different between sites. The elevated level of these perturbation indicators could be related to the raw and treated domestic sewage released directly into Kuramo Water from point and non-point sources. A total of 16 taxa and 691 macrobenthic individuals belonging to 11 families were recognised at the study sites. A naidid and a chironomid species were the most abundant, occurring in high numbers throughout. Other invertebrate groups occurred in low numbers. The diversity indices calculated supported this trend. The generally low diversity further supports the observation that Kuramo Water is a disturbed environment. The absence of molluscs in the benthic invertebrate samples of this study, compared to their dominance in earlier studies of Kuramo Water, reflects a modification in the habitat resulting from a change in the salinity from brackish to freshwater.

A comparative study conducted on three swampy water bodies draining through the University of Lagos into the Lagos Lagoon describes the physical, chemical and macrobenthic invertebrate characteristics of these water bodies at the study sites. Three stations, one at each water body were sampled fortnightly from June to December, 2000. Water temperature, total alkalinity and salinity were the only physical and chemical conditions significantly different at the study stations. The physical and chemical conditions at stations A and B were similar and significantly different from station C exposed to domestic effluent, thereby, reflecting the perturbational stress at that site. A total of 43 benthic invertebrate taxa belonging to five classes, 31 families and 2424 individuals were recorded at the study stations. The study stations can be ranked as B > A > C and B > C > A in terms of number of taxa and number of individuals, respectively. The low number of taxa and individuals in stations A and C is suggestive of habitat instability. The pattern of invertebrate distribution and abundance was influenced by the fluctuations in the abundance of Oligochaeta, Hemiptera and Diptera. The taxon richness (D), genera diversity (H) and evenness (E) estimated for the study sites supported the trends observed in the numbers of taxa occurring and their abundance. The low concentrated dominance (C) calculated for station B compared to stations A and C reflects an ecologically heterogenous and relatively stable site. Morisita-Horn index showed that station C was dissimilar to stations A and B. Jaccard's coefficient indicated that all stations were dissimilar. In general, the faunal comparison showed that the level of exposure to urban discharges, inert pollutants and the presence of aquatic macrophytes influenced the differences in the abundance, occurrence and number of taxa at the three stations.

The aim of the paper is to identify macroinvertebrates distribution in response to induced stressors and physico-chemical parameters of water and sediment. The species composition of macrobenthic invertebrates as well as the physico-chemical characteristics of Badagry creek was investigated monthly. Six sampling stations selected based on different levels of human activities along the creeks stretch and samples were collected monthly from September 2006 to February 2007. The fluctuations of some of the physical and chemical parameters such as pH, dissolved oxygen, BOD and total organic carbon appeared to have been influenced by activities along the study stretch. Analysis of variance (ANOVA)  for all parameters showed no significant differences (P > 0.05) in the parameters but  Post hoc tests analysis using Duncan showed that there was a significant difference (P = 0.05) in the mean total of some of the parameters. pH, clay, sand and gravel were significantly correlated with other parameters while canonical correspondence analysis (CCA) model showed that the environmental variables correlated with significant part of the variations in the individual species abundance and it revealed that dominant species were found to be significantly correlated with dissolved oxygen, total dissolved solids, sand and pH.

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