Ultrastructural alterations in gill, stomach and intestine of two coastal fish species collected from PAHs contaminated area at Digha coastal belt.

Digha is an ideal seaside resort town; its beautiful beaches attract about 2 million people/year. It is also an important site for biodiversity and fishery resources that contribute to the national economy. PAHs are the common organic pollutants in the coastal areas, especially in the harbouring areas, that pose significant risk to the coastal ecosystem as well as human health. Present study intends to analyse the probable threat of polycyclic aromatic hydrocarbons (PAHs) contamination to the coastal ecosystem, particularly to the coastal fish species (Mystus sp. and Mugil sp.). For this we studied the concentration of different PAHs compounds in the coastal water and bottom sediment by GC-MS analysis as well as cellular and subcellular alterations in the gill, stomach, and intestine of that two intoxicated fish species through scanning electron microscopy (SEM). Result revealed the high concentration of PAHs in the coastal water of different study area ranging from 133 to 248.49 ppb, comprising naphthalene, fluorene, and indeno[1,2,3-c,d]pyrene as predominant compounds; concentration in the sediment was higher than the water it varies from 92,009.23 to 100,736.2 ppb, dominated by chrysene, benz[a]anthracene, benzo fluoranthene, and indeno[1,2,3-c,d]pyrene. Ultramicroscopic observations revealed the major cellular and topological distortions in the gill, stomach, and intestine, such as breakage and damage of the gill rakers, clubbing of the gill lamellae, degeneration, fragmentation, excess mucus secretion, loss of normal texture of duodenal villi, and disorganization of columnar epithelial cells (CECs). So, the present study has established a serious impact of PAHs contamination on fish species which may also subsequently affect the human health and coastal ecosystem as a whole.