Histopathology of the Foot, Gill and Digestive Gland Tissues of Freshwater Mussel, Lamellidens marginalis Exposed to Oil Effluent

Abstract

We investigated the histopathological alterations in the tissues of freshwater mussel, Lamellidens marginalis in response to oil effluent. Based on the previous acute toxicity, two sub lethal [1/4th (11.88ppt) and 1/10th (8.55ppt)] concentrations of oil effluent (hydrocarbon) were prepared and exposed to mussels. In a first series of experiment, animals were exposed/accumulated for 30 days [Ist, 8th, 15th, 22nd and 30th days] by two sub lethal concentrations of oil. In a second series of experiment, oil exposed animals were thereafter transferred to clean water and kept in it up to 30 days [Ist, 8th, 15th, 22nd and 30th days] to assess the recovery pattern (depuration). At seven-day intervals, histopathological alterations were analyzed in foot, gill and digestive gland tissues of mussel. First series of experimental observation showed remarkable damages in foot (disorganized outer epithelium, necrosis of the cell, the formation of lumina, disorganized muscle bundle); in gill (disruption of gill filaments, odema formation, necrosis, dis-aggregated cilia) and in digestive gland (stoma, detached glandular epithelium, vertical clefts, presence of leucocytes, dense accumulation of luminal material) and also oil effluent inducement are confirmed with the aforementioned results. At second series of experiment, it was found that oil effluent tended to accumulate in tissues in a duration-dose-dependent manner. Tissue burden by oil effluent of mussels completely were restored at 30th day. The present experimental findings may be of early warning signals of oil effluent pollution. In conclusion oil effluent are highly toxic to the Lamellidens marginalis.