چکیده (انگلیسی):

Gill histomorphological alterations were used to assess the effects of chronic exposure
to HgCl2 on the yellowfin seabream, Acanthopagrus latus. In this regard, 90 A. latus were
exposed to sublethal concentrations of HgCl2 (10, 20, 35 and 50 g/L) for 3 weeks. Treated
fish were erratic and showed respiratory distress. The most common morphological abnormalities
included: filaments disorganization, increase of mucus secretion, debris and blood
plaques on the filaments, losing or shortening of some filaments. The most frequent
histopathological changes detected in the gills included extensive lifting of the lamellar
epithelium and edema of lamellae with enlarged sub-epithelial spaces, exfoliated epithelium
of lamellae, telangiectasia, hypertrophy and hyperplasia of the epithelial cell resulted
in partial fusion of the secondary lamellae and a reduction of the water space, club shaping
of gill lamellae, blood congestion. Some more severe alternations found in the gill of fish
exposed to higher levels of HgCl2 (35 and 50 g/L) included lamellar aneurysm and hemorrhages
with rupture of the lamellar epithelium. According to the results of the present
study, mercuric chloride could cause major histomorphological changes in the gill of A.
latus, decreasing its gas exchange capability. Two mercury concentrations (10 and 20 g/L)
used in the present study were in agreement with the concentration of mercury in the
water of different parts of Mahshahr creeks (the north of Persian Gulf) (3.66 to 15 g/L).
Therefore, based on the results the presence of pathological alteration in A. latus inhibited
in the natural environment (Mahshahr creeks) seems to be logical.