Primary Production in the euphotic zone of a Tropical Harbour, Nigeria

摘要

Primary productivity and selected relevant associated physico-chemical parameters in the euphotic zone of Lagos Harbour, a tropical Harbour was monitored at NIOMR Jetty station (Lattitude 6o 25′ 14, 88o N, Longitude 3o 24′ 24, 42o E) on a monthly basis from October, 2012 to March, 2013. Air and surface water temperature ranged from 23.5?C to 28?C and between 27 ?C and 30?C respectively. Alkaline pH ranged 7.81 to 8.45. Brackish salinity varied from 6.2 to 35.4PSU while Electrical conductivity minimum and maximum values were 11200 and 53300μS/cm respectively. Moderate dissolved oxygen ranged between 5.0mg/l and 6.4mg/l, slightly lower than 6.8mg/l standard suggested by FEPA. Total dissolved solid ranged from 7504 to 35711mg/l while Low Alkalinity varied between 12 and 20mg/l. Rainfall minimum and maximum values were 8.8 and 229mm respectively. Gross primary production (GPP) varied from 0.22 to 0.46gC/m2/day. The corresponding Net primary production (NPP) and Community respiration (CR) ranged from 0.07 to 0.3gC/ m2/day and 0.144 to 0.31gC/m2/day respectively. GPP correlated positively with NPP (r = 0.69), Dissolved Oxygen (r = 0.56) and significantly correlated negatively with Alkalinity (r = -0.86) at P & 0.05. NPP also correlated positively with Dissolved Oxygen (r = 0.80). This investigation revealed that the productivity of Lagos Harbour is impacted by various factors such as sand mining and dredging, industrial effluents, sewage water and other anthropogenic activities. The information and observation of this study will be very useful as baseline data against which future changes can be measured.