Seasonal change in mental concentrations in selected tissues of the red-knobbed coot, Fulica cristata, from a metal-polluted wetland

Abstract

The Red-knobbed Coot Frdico cristata is anticipated to be a useful indicator of Cd, Cu, Ni and Pb which are commonly found in effluents and seepage waters from mines, industries and sewage purification works. This investigation was conducted on coots collected from the Natalpruit wetland, which is polluted by metal-containing effluents from mines and sewage works as well as urban runoff. The main objective was to determine whether seasonality can influence the concentrations of these four metals in the liver, kidney, bone and blood of coots sampled during four consecutive winter and summer seasons from 1991 to 1993. Use was made of dried material and analysed with flame atomic absorption spectrophotometry. Cd occurred in the lowest concentrations in all the tissues during all four seasons. Cu in the kidney (22 m/g) and liver (27 m/g) as well as Pb in the bone (33 m/g) and blood (19 m/g) had the highest mean concentrations for the four seasons combined. Only kidney Ni and bone Cd reflected significant (p < 0.05) changes during the four successive seasons. However, in most other cases slight seasonal changes were observed. For instance, the Ph (liver) and Cd (kidney) concentrations were significantly higher during winter 1991 whilst Cd and Cu (both in the blood) were significantly lower during winter 1991 when compared to the succeeding three seasons. Concentrations of Cd and Cu in the liver, Pb in the blood and bone and Cu in the kidney showed no significant seasonal trends. It is concluded that a number of factors in both the abiotic and biotic components may have had an effect on fluctuations in metal concentrations, by acting individually and / or synergistically.


Water SA Vol.29(1) 2003: 91-99