Variations in the physico-chemical parameters of water quality of coastal waters of Lagos State, Nigeria

Abstract

Background: The marine and brackish waters are dynamic aquatic environment and complex systems mainly influenced by various physical and chemical processes.  Physico-chemical parameters such as temperature, rainfall, pH, dissolved oxygen and salinity play important role in influencing the aquatic environment.  Objectives: This study was conducted on physico-chemical water quality parameters of water from marine waters (LC) and brackish waters (LLC) of Lagos state and aimed at assessing the suitability of the environment for fish production. Methods: Seven (4 LC and 3 LLC) stations were selected and seven physico-chemical parameters were investigated monthly by standard methods of APHA. Data on temperature, pH and dissolved oxygen (DO) were obtained in-situ using mercury-in-glass thermometer, pH meter and DO meter respectively. Salinity, dissolved oxygen, total alkalinity, total suspended and dissolved solids were obtained in the laboratory using standard methods.  Results: The result showed that LC and LLC had pH, 7.74 ± 0.21 and 7.44 ± 0.11; DO 6.88 ± 0.24 mg/l and 7.11± 0.24 mg/l; Temperature 29.04 ± 0.11ºC and 29.0 ± 0.02ºC respectively as mean values. Salinity 29.06 ± 0.68‰ and 10.38 ± 0.48%; TDS 22.58 ± 0.22 mg/l and 8.12 ± 1.14 mg/l and total alkalinity 109.74 ± 0.22 mg CaCo3 /l and 123.5.18 ± 1.12 mg CaCo3 /l showed significant difference between the marine and brackish waters environments at P ˂ 0.05.  Conclusions: The water parameters favoured the survival and production of fish from both the LC and LLC water despite the differences in the salinity gradient of the two environments. High dissolved oxygen content indicated that the coastal water of Lagos state can successfully support aquatic life including fish.

Keywords: Physico-chemical parameters, marine waters, brackish water, salinity, temperature, dissolved oxygen