OBSERVATIONS ON ABUNDANCE AND FECUNDITY OF THE INVASIVE SNAIL PHYSA ACUTA IN WEST BENGAL, INDIA: IMPLICATIONS FOR MANAGEMENTChilka Saha, Joy Chakraborty, Soujita Pramanik, Saida Parveen and Gautam Aditya
An assessment of the relative abundance and fecundity of the invasive freshwater snail Physa acuta Draparnaud, 1805 (Gastropoda: Physidae) was made using Burdwan, West Bengal as the geographical area. Sampling of the sewage drains of the study area revealed the presence of the snail P. acuta in varying numbers and size classes representing the heterogeneity of the population in the habitat. Although the sites did not exhibit any difference in the population structure, proportional representation of the size classes varied significantly as revealed through the logistic regression: relative abundance (y) = 1 / (1 + exp(-(-2.79 + 0.006 *x1(site) +0.13*x2(size class)))). The snails above the size class of 8 mm shell height showed a positive correlation for eggs (r267 = + 0.952; P <0.001) and could be represented through the regression equation as: y (ln eggs) = 0.791x (SH) - 5.534. The results indicate that the snails have established in the sewage drain habitats of the area concerned, with a potential to expand in future. The present observation is pioneer in deciphering the population structure and size fecundity of the snail P. acuta outside of Kolkata, India. Further studies should be initiated to predict the changes in the habitat conditions and alteration of the species interactions in the freshwater ecosystems of West Bengal, and other regions of India.
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