Abstract:
Fish is one of the best organisms in many scientific studies to evaluate heavy metal pollution and
human health hazards as they are well-understood organisms in the aquatic environment. The
present study was carried out to examine the level of heavy metals in different tissues of Etroplus
suratensis (Green chromide) in Koggala lagoon, Sri Lanka. Atomic absorption spectrophotometer
(AAS) was used to determine the levels of copper (Cu2+), cadmium (Cd+3), lead (Pb+2), and
chromium (Cr+3) ions in the different tissues (skin, liver, gill, and flesh) of fish belonging to three
different sizes; small (7.8–10.2) cm, medium (14.1–16.6) cm, and large (19.8–25.2) cm. The
number of thirty-six fish were collected from the lagoon randomly. According to available sizes, 12
fish for each size class were used for the analysis. Furthermore, the histological analysis was carried
out to identify the changes at the tissue level in the gill and liver of fish in three different size
classes. Heavy metal concentrations in fish samples were compared with the standard levels of
heavy metals. Heavy metal concentrations in body tissues of three different body sizes of fish were
found to be mainly in the order of Cu>Pb>Cr> Cd. The highest concentrations (P<0.05) of heavy
metals were found in the fish flesh and skin, while the lowest concentrations were found in the gills.
The range of heavy metal concentrations (g g-1 dry weight) in body tissue of small size, E.
suratensis fish were, Cu: 0.0443-0.6210, Cd: 0.0110–0.0214, Pb: Below Detection Level (BDL)-
0.46 and Cr: BDL-39.633, Medium size fish were, Cu: 0.0713–0.6210, Cd: 0.0134-0.0170, Pb:
BDL-40.906, Cr: 0.0014–0.0500 and large fish were, Cu: 0.0553–0.345, Cd: 0.0110–0.0256, Pb:
0.0204–0.2103 and Cr: 0.0194–0.0773. However, Cd, Cr and Pb concentrations of flesh tissues
were under the standard recommended limits referred by the FAO. Through the Cu concentration in
flesh, tissues exceeded the standard limits of FAO. It is not considered as a toxic heavy metal.
Histological analysis revealed that the deviation of shape of hepatic cells in the liver may due to the
exposure to heavy metals in the lagoon. According to the overall result, the bioaccumulation and
biomagnification nature of heavy metals, and the consumption of E. suratensis in the Koggala
lagoon may create health hazards to consumers.
