ABSTRACT:Benthic macro-invertebrates of the Northern axis of metropolitan segment of Lagos Lagoon sediments, Nigeria were investigated for six months (April -September, 2010). The study was aimed at using benthic macro-invertebrates to assess the water quality of this part of the Lagoon. A total of ten taxa belonging to three major animal phyla from a total of 2,672 individuals were encountered. The dominant taxa throughout the study and stations were Pachymelania aurita, Aloidis trigona, and Neritina glabrata. Station A (Ikorodu port) had seven taxa, station B (Ibese) had five while stations C (Ofin) and D (Oreta) had eight taxa each. Stations A(Ikorodu port), B(Ibese), C(Ofin) and D(Oreta) accounted for 8.19%, 0.94%, 79.83% and 11.04% respectively in all the individuals collected. Gastropoda was highest and accounted for 54.83% of all individuals collected from all stations contributing 2.58% at station A and 0.49%, 48.39% and 3.37% respectively at stations B, C and D, while Polychaeta had the least (0.97%) with station A, B, C and D constituted 0.82%, 0.04%, 0.04% and 0.07% respectively. Sediment type of the study areas was predominantly muddy sand. The presence of more pollution tolerant species (Nereis spp, Capitella capitata and Polydora ciliata) in station A may serve to confirm that the community has been impacted by pollution. The low faunal abundance and diversity observed in station B could be attributed to stress imposed by effluents from industrial sources. The information of this study will be very useful in formulating policies and regulatory framework for sustainable management of Lagos Lagoon. @JASEM

Investigations were carried out on spatial and seasonal composition and distributions of phytoplankton in some parts of the Lagos Lagoon. Phytoplankton samples were collected from twelve stations during the wet (July, 2008) and dry (March, 2009) seasons. A typical freshwater condition prevailed in the study area during wet season with salinity of 0 parts per thousand (o / oo) at every station, whereas during the dry season, relatively high salinity levels were recorded from all the stations with decreasing trend toward the river mouth. The two seasons had the diatoms (Bacillariophytes) of the Orders Centrales and Pennales as the dominant phytoplankton taxa. A total of 2896 phytoplankton belonging to twenty-seven species, eight orders and four classes were recorded during wet season while the dry season had a total of 1550 phytoplankton, which cut across sixteen species, three orders and two classes. Wet and dry seasons respectively had Aulacoseira granulata and Coscinodiscus sps. as the dominant phytoplankton taxa. Higher dominance (0.33) and Margalef diversity (3.26) but lower Shanon-Wiener diversity (1.94) and evenness of distribution (0.26) indices were recorded during the wet than dry seasons. The findings show the influence of seasonality on phytoplankton composition and distributions in the Lagos Lagoon and suggest relatively stress-free environmental conditions within the study area.

Some physico-chemical parameters of Badagry Creek and Ologe Lagoon in the Barrier Lagoon Complex of western Nigerian coastal zone were measured on quarterly basis from June 2011 to May 2012. Water samples were collected and analyzed using standard methods at five stations in each of the two water bodies. A brackish condition was observed in Badagry Creek with salinity range of 2.00 ± 3.8 ‰ to 3.85 ± 4.48 ‰ while entirely freshwater condition was recorded in Ologe Lagoon. Surface water temperature, pH, alkalinity, nitrate and phosphate at every station in the two water bodies were within the normal ranges considered suitable for tropical aquatic life. However, high levels of biochemical oxygen demand (BOD) were recorded at a station in Badagry Creek (8.15 ± 1.66 mg/l) and two stations in Ologe Lagoon (16.9 ± 10.46 and 9.40 ± 7.56 mg/l), where untreated municipal wastes are being discharged into the water bodies. These stations also had relatively low dissolved oxygen (DO) levels (3.30 ± 0.22, 1.08 ± 0.96 and 3.68 ± 3.2 mg/l respectively). Relatively high levels of lead were also recorded at these stations (0.50 ± 0.42, 0.85 ± 0.07 and 0.35 ± 0.35 mg/l respectively). The implications of the physico-chemical conditions on bio-communities as well as the imperativeness of regulating the discharge of untreated wastes into the water bodies for their sustainable management and conservation are discussed.