Limnochemical Factors Influencing the Seasonal Population Density, Secondary Production, and Calcium-to-Tissue Ratio in the Freshwater Limpet Septaria lineata (Archaeogastropoda: Neritidae)

Authors: ASITAVA CHATTERJEE, MANJARI JAIN, UTPAL SINGHA ROY, SUBHRA KUMAR MUKHOPADHYAY

Abstract: The distribution, secondary production, and calcium:tissue (Ca:tissue) ratio in relation to limno-chemical factors were studied in a freshwater limpet (Septaria lineata) population from the west bank of the River Hooghly, West Bengal, India, for 2 successive years. Total hardness, chloride, pH, and phosphate were shown to be significant in Pearson´s correlations in influencing the abundance of the limpet population. Annual production for the 2 successive years was 10.3 g m^{-2} and 9.5 g m^{-2}, respectively. The annual turnover ratios, the ratios of annual production (P) and annual standing crop (B), ´P/B´, were calculated to be 2.06 and 1.67, while annual turnover times were 177 days and 219 days, respectively. The ratio of whole animal shell calcium content to tissue dry weight (shell Ca:tissue ratio) changed with age and size class, but these changes were largely restricted to early growth and did not significantly affect individuals over a particular size class (shell height 40-49 mm). Total hardness and chloride were the most important limnochemical factors influencing the shell Ca:tissue ratio.

Keywords: Septaria, freshwater limpet, secondary production, population density, Ganga

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