Assessment of gill pathological responses in the tropical fish yellowfin seabream of Persian Gulf under mercury exposure

Abstract

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 μg/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 μg/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 μg/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 μg/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.

Histological Biomarkers in Fish as a Tool in Ecological Risk Assessment and Monitoring Programs: A Review

“…According to Mohamed (2009) the liver is also a target organ due to its large blood supply, which causes noticeable toxicant exposure. Moreover, the liver is reported to be the primary organ for bioaccumulation and thus, has been extensively studied in regards to the toxic effects of different xenobiotics (Hinton and Laurén, 1990 (Hassaninezhad et al, 2014 According to Strüssmann and Takashima (1990) morphometric parameters such as number of hepatocytes, hepatocyte area core region of hepatocytes, glycogen content and lipids into the cytoplasm are commonly used as an indicator for hepatocyte metabolic activity.…”

Liver biomarkers response of the neotropical fish Aequidens metae to environmental stressors associated with the oil industry

“…Water eutrophication can lead to lesions in fish gills such as lamellar hyperplasia in a first attempt to increase gill surface area. Paradoxically, hyperplasia can provoke laminar fusion leading to a reduction of water space and of gas exchange capacity ( Dalzochio et al., 2017 ; Hassaninezhad et al., 2014 ). It must also be considered that river water phosphate levels have shown a dramatic increase by a factor of more than 10 over the past 20 years, mainly due to anthropogenic inputs ( Yang et al., 2008 ).…”

“…Water eutrophication can lead to lesions in fish gills such as lamellar hyperplasia in a first attempt to increase gill surface area. Paradoxically, hyperplasia can provoke laminar fusion leading to a reduction of water space and of gas exchange capacity (Dalzochio et al, 2017;Hassaninezhad et al, 2014). It must also be considered that river Dry season (DS); rainy season (RS); # For alkalinity parameter a statistical difference was observed among the monitoring sites for the same season Below detection limit * Detected below limit of quantification.…”

A review of mercury pathological effects on organs specific of fishes

“…The duration of the experiment taken for the chronic exposure through methylmercury for short term and long term can be reached up to 0 (12 hours (h)) to 4 weeks [28] and 2.7 to 8 weeks [32], respectively. For acute toxicity, 96 h of lethal concentrations at 50% (LC 50 ) were determined with the average duration for short-term of inorganic mercury exposure were between average of 4 to 96 h [28,36,37] and long term that up to 3 weeks [37,38]. Besides, a study on tissue changes due to mercury contamination of wild fish from the natural environment that was exposed to mercury was also included in this review [27,39].…”