Fish species abundance and distribution in The Gambia estuary

Darboe4.1.3 Dissolved oxygenOxygen is among the important factors that affect the distribution of fish. Fish tend toavoid waters deficient in dissolved oxygen. During high discharge periods thetendency for areas with very low transparency to be anoxic could be high due to highconcentration of suspended mud particles that could not only impede photosyntheticprocesses but could also increase biological oxygen demand (BOD) in the processesof decomposition of organic matterThe results of the study indicate both surface and bottom concentration of dissolvedoxygen following similar patterns of oscillation throughout the estuary (Figure 8). Thehighest measurement of (8.1mg/l) was recorded at the mouth of Katchang creek inApril (survey 5) while the lowest (2.84 mg/l) was recorded in Bintang bolongtributary in November 2000. In the context of the whole estuary, a slight upstreamincrease of dissolved oxygen concentration was observed.UNU – Fisheries Training Programme 16