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

Environmental variables, algal pigments and phytoplankton in the Atlantic Ocean off the coast of Badagry, Lagos

The phytoplankton diversity, environmental variables and algal pigments of the Atlantic Ocean off the coast of Badagry, Lagos were investigated for twelve months between May 2015 and April 2016. The water chemistry characteristics reflected sea water conditions. At the two stations, the range of values recorded for some physico-chemical variables were rainfall (4.1 - 449.3mm), air temperature (23 - 30°C), water temperature (25-31°C), salinity (26.6 - 31.81‰), pH (7.9 - 8.12) and total dissolved solids (26980.1–32900.1mg/L), The phytoplankton diversity consisted of 44 species belonging to three main algal groups namely: 30 species of diatoms (Bacillariophyta) making up 80.49%, five species of blue-green algae (Cyanophyta) making up 13.57% and nine species of dinoflagellate (Dinophyta) accounting for the remaining 5.94%.. Notable species were Coscinodiscus centralis, Coscinodiscus radiatus, Thalassionema nitzschioides and Thalassionema longissima (Diatoms) and a blue-green algae Trichodesmium thiebautii. Nitrate was the key limiting nutrient with regards to algal pigment concentration. The values for the correlation of chlorophyll a (r=0.590, p <0.05), chlorophyll b (r=0.496, p<0.01) and phaeophytin a (r=0.286) with nitrate were significantly positively correlated. Hence, Nitrate is the trigger nutrient for increased algal pigments concentration in the study area.Keywords: Sea, Lagoon, neritic, diatoms, physico-chemical, phytochemical

The hydro-environmental conditions and zooplankton of the light house creek, Lagos, Nigeria

The hydro-environmental characteristics and zooplankton diversity at the Light-house creek were investigated for six months. Variations in water quality parameters were linked with tidal sea water incursion and rainfall/floodwater dynamics. Water and air temperatures were high (>25.8⁰C; >28 ⁰C) and Transparency decreased in the wet months. Salinity values were high (>19 ‰) all through, while the water remained alkaline (≥6.68). Biochemical oxygen demand (4.0-18.0 mg/L), chemical oxygen demand (1.0 and 2.0 mg/L) phosphate (0.06 and 8.40 mg/L) and nitrate showed variations (0.80 mg/L). On the other hand, minimum sulphate value was 224.0 mg/L while silicate values ranged from 2.10 to 4.60 mg/L. Zinc (<0.047 mg/L), Iron (<0.28 mg/L) and copper values (<0.014 mg/L) also varied. The zooplankton spectrum comprised 62.36% Arthropoda, 0.78% Chordata, 0.71% Cnidaria, 35.9%, juvenile stages and 0.95% were from other groups. A total of 49 zooplankton taxa from five different phyla and 18 juvenile stages were identified. Zooplankton biomass in terms of individuals per ml was higher in the dry than wet months. The copepod nauplii, bivalve and zoea larvae were the dorminant juvenile forms. Species richness indices (d) and similarity index were higher in the dry months than the wet months.Key Words: Phytoplankton, juvenile stages, Lagos habour, lagoon, water chemistry, mangrove cree