Investigation of phytoplankton distributions in the westernmost part of Barrier-lagoon-complex, Western Nigeria

Distributions of phytoplankton were studied in two contiguous water bodies (Badagry Creek and Ologe Lagoon) within westernmost part of the Barrier-lagoon complex in Nigeria. Phytoplankton samples were collected and analysed using standard methods at five stations in each of the water bodies in September 2011, February and May 2012. Phytoplankton recorded from the two water bodies belonged to Classes Bacillariophyta, Chlorophtya, Cyanophyta and Euglenophyta. Total phytoplankton species of 92 and 94 were recorded in Badagry Creek and Ologe Lagoon respectively indicating relatively high diversity and productivity of the two water bodies. Bacillariophytes dominated the phytoplankton communities in the two water bodies constituting about 88% and 58% in Badagry Creek and Ologe Lagoon respectively. In terms of abundance, Badagry Creek was dominated by species only from the Class Bacillariophyta whereas each of the Classes Bacillariophyta, Chlorophyta and Cyanophyta had species with very high abundance in Ologe Lagoon. In Ologe Lagoon, two stations close to discharge points of municipal and abattoir wastes had low phytoplankton species number and diversity but high abundance of pollution indicator and harmful species of such genera as Volvox, Microcystis and Oscillatoria. The undesirable effects of the anthropogenic activities and the need to regulate them for sustainable management of the water bodies and the resources therein are discussed.Keywords: Coastal waters, phytoplankton distribution, phytoplankton abundance, productivity, anthropogenic activities, harmful algae

Study of physico-chemical characteristics of the westernmost part of the barrier Lagoon complex, Western Nigeria

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.Keywords: Physico-chemical parameters, Badagry Creek, Ologe Lagoon, untreated waste discharge, Organic pollution

Distribution of phytoplankton in some parts of Lagos Lagoon, Southwest Nigeria

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, relativelyhigh 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 dominantphytoplankton 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 Margalefdiversity (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 phytoplanktoncomposition and distributions in the Lagos Lagoon and suggest relatively stress-free environmental conditions within the study area