The Effects of Sewage Discharge on The Marine Gastropod Gibbula sp., Collected From The Coast of Al-Hanyaa, Libya

Marine gastropods are known to accumulate high metal concentrations in their tissues especially in the digestive glands. In this study, the accumulation of Cu, Zn, Cd, Cr and Pb in the gastropod Gibbula sp. (Family: Trochidae) has been assessed using Atomic absorption, spectrophotometry graphite Furnace. Animals were collected from rocky shores at Al-Hanyaa region on the north-east coast of Libya. Two groups of animals were studied; one from an area adjacent to a sewage outlet and the second was collected from a relatively clean site. Concentrations of metals in the viscera, of both adults and juveniles, of Gibbula collected from the polluted site were higher than that recorded in the clean site. Thus, there is a tendency for Gibbula tissues in the polluted area to have higher concentrations of metals although the differences are not always statistically significant. The values recorded for adult specimens collected from the polluted and non polluted locations were 0.51±0.27, 15.95±1.28, 0.021±0.017, 0.47±0.18, 0.60±0.17 vs 0.40±0.11, 9.51± 4.82, 0.03 ± 0.02, 0.29 ± 0.09, 0.39 ± 0.09 for Cu, Zn, Cd, Cr and Pb µg ⁄mg, respectively. Whereas, those recorded for juveniles were 0.51±0.09, 17.02±1.13, 0.032±0.01, 0.49±0.15, 0.54±0.17 vs. 0.38±0.22, 8.36±2.05, 0.020±0.01, 0.35±0.25, 0.52±0.12 for Cu, Zn, Cd, Cr and Pb µg ⁄mg, respectively. It is suggested that metals are taken up by Gibbula sp. viscera directly from the water or from the ingested algae. Also, the shell mass was affected with the pollution.