Abstract :
Bivalves have been widely used as bioindicators of aquatic habitats because their ?lter-feeding habit leads to the accumulation of pollutants from the environment. Tapes decussatus is a common edible venerid clam bivalve in Egypt and has particular importance because its habit of penetrating sea sediments can provide information about the surrounding environment. Gill ?laments have a large surface with constant contact with water and are therefore used to monitor aquatic environments. In this study, total hydrocarbons and heavy metals were measured in two sites of Egypt, Cleopatra shore (Marsa Matrouh) and Port of Suez (Suez); scanning electron microscopy (SEM) was used to examine the morphology of Tapes decussatus gill ?laments and to compare the gill structure in specimens from the two sites. Cleopatra site presents low levels of heavy metals and hydrocarbons undetected, whereas Port of Suez site recorded high levels; because it was directly affected by industrial discharges and harbor pollutants. The gill ?laments of T. decussatus have three types of cilia; frontal cilia, latero-frontal cilia, and lateral cilia. Structures joining the inner and outer gill lamellae were found on the abfrontal surface. By comparing the gill of the clam from the two sites; there was an aggregation of particles on the ostia, appearance of bacterial communities at the abfrontal surface of gill fillaments and accumulation of mucus on the frontal surface of the gill ?laments of specimens which collected from Suez Port site.This mucus may function as a protective barrier against pollutants
Keyword :
Bivalvia; Veneridae; Tapes decussatus; Filter-feeding; Gill; Pollutants; Scanning Electron Microscopy