Turritella attenuata (Kasinathan): as biological indicator of marine pollution--a trace metal analytical study.

A study to monitor marine pollution with reference to trace elements (Fe, Zn, Mn and Cu) on T. attenuata, commonly called as screw shell over a period of one year on the whole body and various organs, viz. digestive diverticula, foot, mantle and ovary was conducted from the sandy beach of Porto Novo Coast (Lat 11 degrees 29' N Long: 79 degrees 46' E) of Peninsular India using Atomic Absorption Spectrophotometer (AAS). Higher concentration of all the four trace metals analysed were recorded in the digestive diverticula, whereas lower concentration of zinc and manganese were recorded in the ovary during the monsoon period. The higher level of trace metal concentration in the monsoon period may be due to the presence of these pollutants in large amounts in water. The accumulation of selected trace metals varies in different seasons according to the extent of pollution load in the marine environment.

Ammonium sulphate induced stress related alterations in the respiratory epithelium of the airbreathing organ of the catfish Heteropneustes fossilis (Bloch).

In this paper, histopathological changes in the inner lining of the accessory respiratory organ of Heteropneustes fossilis following exposure to sublethal concentration (0·2 g I -1) of ammonium sulphate (3 mg I-1 total ammonia-N) has been described. The goblet cells show periodic increased followed by decreased secretory activities. Necrosis and shedding of the epithelial cells over the secondary lamellae cause periodic haemorrhages which lead to degeneration and decreased number of secondary lamellae. Subsequently regeneration takes place each time as evidenced by the appearance of inflammatory tissue. Fusion of more than one secondary lamellae is also common. Regeneration also leads to uncontrolled hyperplasia of haphazardly arranged epithelial cells. This hyperplasia causes increased distance of respiratory blood-air barrier in the secondary lamellae, leading to impaired normal aerial respiration.