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

Research Article

Austin J Environ Toxicol. 2021; 7(1): 1033.

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

Balamurugan S¹* and Subramanian P²

¹Department of Zoology, Arignar Anna Government Arts College, India

²Department of Animal Science, Bharathidasan University, India

*Corresponding author: Balamuirugan S, Department of Zoology, Arignar Anna Government Arts College, Musiri-621 211, Tiruchirappalli-District, Tamilnadu, India

Received: December 04, 2020; Accepted: December 30, 2020; Published: January 06, 2021


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.

Keywords: Oil effluent; Accumulation and depuration; Histopathology of foot; Gill; Digestive gland; Lamellidens marginalis


EP: Epithelium; MU: Muscle Tissue; CI: Cilia; NE: Nucleus; BS: Blood Sinus; MU: Muscle Tissue; NE: Necrosis of Epithelial Tissue; GF-Gill Filaments: CR: Chitinus Rod; FL: Frontal Lateral Cilia; FC: Frontal Cilia; IS: Interlamellar Space; IJ: Interlamellar Junction; WC: Water Chamber; MU: Muscle Tissue; SC: Supra Brachial Chamber; GF: Gill Filaments; FL: Frontal Lateral Cilia; DD: Digestive Diverticula; LU: Lumen; ST: Stomach


Researchers with different expertise have converged towards a common interest for understanding and solving the problems associated with the occurrence of toxic level of contaminants in the environment, giving raise to the spectacular development of research in the field of Environmental Contamination and Toxicology, which has emerged as a multidisciplinary science resulting from the integration of classical disciplines such as toxicology, cell and molecular biology, physiology, ecology, chemistry, etc [1]. Uptake and accumulation of xenobiotics in the tissues of aquatic organisms occur from the sediment, contaminated water column and food chain [2] that cause deleterious effects. Incorporation of even very low levels of toxicants in the body of aquatic organisms causes various biochemical, physiological and hematological alterations in vital tissues [3]. Most common usage of the term biomarker has been for biochemical, physiological or histological indicators of their exposure to or the effects of xenobiotic chemicals at the sub-organismal or organismal level [4]. Most of the monitoring programmes are confined to the chemical analysis of accumulated substances, but sometimes include toxic responses, for instance histopathological effects [5,6] or physiological/biochemical responses [7]. When Polycyclic Aromatic Hydrocarbon (PAHs) exposed animals, several deleterious effects such as DNA damage [8]. As an indicator of exposure to contaminant, histology represents a useful tool to assess the degree of pollution, particularly for sub lethal and chronic effects [9]. Histological changes appear as a medium-term response to sub-lethal stressors, and histology provides a rapid method to detect effects tissues and organs [10]. Summary of some relevant earlier literature on marine as well as freshwater mussels histopathological observations with various toxicant exposure results are compiled (Table 1). In molluscs, especially in Lamellidens marginalis histological injuries, in response to the exposure to oil effluent, remains unexplored. Gills are the vital organs, which come into direct contact with water and are indicative of any environmental stress and also in fishes gills are the major vital respiratory organs [11]. The numerous lamellae along the double row of filament attached to the gill arch are affected by toxicants [12]. Molluscs are widely used in different biomonitoring projects and their histopathological analysis provides information about the general health of the animals and contaminant-specific changes in the tissues. Although laboratory as well as field studies suggest that pollutants cause toxic effects to molluscs, the histopathological effects of chemical contaminants have not generally been measured [13]. Blue mussels can retain on their gills, including oil particles have observed [14]. Like numerous bivalves, they concentrate many xenobiotics in their tissues and have been used extensively for biomonitoring of pollutants [15] but there is inadequate contribution on freshwater mussels. Gills [16] are suitable organs for histological examination in order to determine the effect of pollution. Histological changes occurs in the bivalves especially in the hepatopancreas (digestive gland) as they are the metabolically active sites and are responsible for food collection, absorption, digestion, enzymatic activity as well as accumulation and biotransformation (detoxification) of various organic and inorganic toxic substances upon exposure to the organic and inorganic contaminants in the water. Pathological changes in the vital tissues of bivalves have been reported after pollutant exposure [17,6]. Owing to their poor existence and meagre information about the histopathology in invertebrates remarkably in freshwater mussels. This present study attempts to understand the pathological injuries in mussels. Therefore, present investigation were examined during acumulation (30 days) and depuration (recovery) period (30 days) in response to sub lethal concentration of 1/4th (11.88ppt) and 1/10th (8.55ppt) of oil effluent in freshwater mussel tissues of foot, gill and digestive gland. The aims of present study were to observe (1) histopathological damages in foot, gill and digestive gland tissues of mussels during accumulation period of both sublethal concentrations of oil effluent in comparison to control (2) whether these histopathological damages in various tissues of mussels recoverd/ restored in the depuration period in comparison to control mussels and (3) whether these alteration/damages would serve as a biomarker to detect the accumulated oil effluent (hydrocarbon) in this species.