Wet season spatial occurrence of phytoplankton and zooplankton in Lagos Lagoon, Nigeria.

Investigation into the spatial occurrence of wet season phytoplankton and zooplankton in Lagos lagoon, Nigeria was carried out in October, 2008 in 12 stations. A total of 36 species of phytoplankton from 21 genera, 20 zooplankton species from 17 genera and 10 juvenile forms were recorded for the study. The results showed that freshwater conditions within the lagoon were due to high freshwater inflow from adjoining waterways and reduced tidal incursion from the sea. The wet season spectrum of the lagoon was dominated by diatoms for the phytoplankton and copepods for the zooplankton. The presence and array of juvenile forms in the wet season suggest that the lagoon remain a sanctuary, nursery and breeding grounds for aquatic species Crustaceans dominated the spectrum of the juvenile forms. Keywords: Plankton, Physico-chemical characteristics, lagoon, juvenile forms, Lagos

Assessment of Polychlorinated Biphenyls (PCBs) in water, sediments and biota from e-waste dumpsites in Lagos and Osun States, South-West, Nigeria

The levels of PCBs in sediments, water, leachate and aquatic fauna (Tilapia guineensis, Callinectes amnicola and Cardiosoma armatum) found in and around e-waste dumpsites in Lagos and Osun States, South-West, Nigeria were analyzed using Gas Chromatography Electron Capture Detector (GC ECD) Agilent 7820A. All the 28 PCBs congeners studied were detected with the Σhexa-PCBs dominating in Lagos (21%) while the Σtetra-PCBs (24%) enriched the samples from Osun State. The concentrations of Σ- PCBs in decreasing order were Lagos: sediment ˃ fish gill ˃ fish muscles ˃ water ˃ crab ˃ leachate and Osun: fish gill ˃ fish muscle ˃ sediment ˃ crab ˃ water ˃ leachate. The concentrations of total indicator PCBs ( Σ7PCBs) in the sediment from Lagos (4.19 μg/kg) and Osun (8.58 μg/kg) exceeded the Canadian Sediment Quality standard threshold effect level (CSQ TEL) (0.03 μg/kg) and the National Oceanic Atmospheric Administration threshold effect level (NOAA TEL) for fresh and marine sediments.. The calculated toxic equivalent quotient (TEQ) for fish from Lagos and Osun (3.7 and 4.4) respectively further suggests a likely occurrence of adverse effects to humans who consume the fish. This study reveals the high health and ecological risks associated with e waste pollution in the aquatic environment.Keywords: e-waste, polychlorinated Biphenyls, aquatic environment, leachat

Seasonal Variations in the Composition and Distribution of Planktonic Fauna in the Eastern Lagos Lagoon, Nigeria

The composition and distribution of planktonic fauna (adult form of zooplankton and planktonic juvenile forms of higher animals) within the eastern part of the Lagos Lagoon were investigated in July, 2008 and March, 2009 representing rainy and dry season respectively. Samples of water and planktonic fauna were collected from twelve stations within the eastern axis of the Lagoon and analyzed using standard methods. The study area had brackish water characteristics with fresh water condition (0\u2030 salinity across the 12 stations) in the rainy season whereas the salinity ranged from 11.4\u2030 to 30.5\u2030 in the dry season. The adult forms zooplankton recorded in the rainy season were mainly Crustaceans, Chaetognathans and Rotifers while those collected during dry season belonged to Crustacean, Cnidaria and Chordata. Crustaceans dominate both adult zooplankton and planktonic juvenile fauna in the two seasons. The rainy season adult zooplankton count (515) was lower than that of dry season (580) but the reverse was the case for the juvenile stages count (520 and 325 in rainy and dry season respectively). Higher species abundance was recorded for both adult zooplankton (20) and juvenile stages (10) in rainy than dry season when 14 and 8 were recorded for the two groups respectively. Higher values were also of community structure indices (Margalef species richness and Shannon-Wiener species diversity) were recorded in the rainy than dry season for the two groups of planktonic fauna. The findings show the influence of salinity gradients on distribution of planktonic fauna of the Lagos Lagoon

Seasonal Variations in the Composition and Distribution of Planktonic Fauna in the Eastern Lagos Lagoon, Nigeria

The composition and distribution of planktonic fauna (adult form of zooplankton and planktonic juvenile forms of higher animals) within the eastern part of the Lagos Lagoon were investigated in July, 2008 and March, 2009 representing rainy and dry season respectively. Samples of water and planktonic fauna were collected from twelve stations within the eastern axis of the Lagoon and analyzed using standard methods. The study area had brackish water characteristics with fresh water condition (0‰ salinity across the 12 stations) in the rainy season whereas the salinity ranged from 11.4‰ to 30.5‰ in the dry season. The adult forms zooplankton recorded in the rainy season were mainly Crustaceans, Chaetognathans and Rotifers while those collected during dry season belonged to Crustacean, Cnidaria and Chordata. Crustaceans dominate both adult zooplankton and planktonic juvenile fauna in the two seasons. The rainy season adult zooplankton count (515) was lower than that of dry season (580) but the reverse was the case for the juvenile stages count (520 and 325 in rainy and dry season respectively). Higher species abundance was recorded for both adult zooplankton (20) and juvenile stages (10) in rainy than dry season when 14 and 8 were recorded for the two groups respectively. Higher values were also of community structure indices (Margalef species richness and Shannon-Wiener species diversity) were recorded in the rainy than dry season for the two groups of planktonic fauna. The findings show the influence of salinity gradients on distribution of planktonic fauna of the Lagos Lagoon