Seasonal variation in fish abundance and physicochemical parameters of Lagos lagoon, Nigeria

Abstract

A Study was conducted to determine abundance of fish over two seasons (dry and wet) in Lagos lagoon. Fish sampling was carried out in four selected stations. Physico – chemical characteristics of Lagos lagoon and fish distribution was also studied. The results revealed that Cichlids contributed the highest number of fish in the two seasons. Fish species were more evenly distributed in the dry seasons than wet seasons. Species evenness for wet and dry seasons was 0.40 and 0.43 respectively. There is a positive correlation between fish abundance and biomass for wet and dry seasons (r = 0.60 and 0.76 respectively). There was no significant difference between fish abundance in the two seasons. Variations occurred between physico-chemical parameters of water samples. Analysis of the lagoon waters showed that oil and grease of 11.0 – 12.0 mg/l higher than the FEPA’S limit for effluent discharge. The oil and grease levels exhibited significant difference (p<0.05) between the dry and wet seasons in all the stations in all the zones and also there are significant relationship (p<0.05) among the stations. It is clear from the results that lagoon pollution can also be traceable to the effluent discharged from transportation and therefore there is a need to take appropriate measures to preserve the aquatic life. The information and observation in this study will be very useful in formulating management policies on the future use of Lagos lagoon especially multi-usage of fisheries with other sectors like oil and transportation.

Key words: Fish distribution, seasonal variation, lagoon.