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

Abstract

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 creek