Morphometric Characteristics and Fecundity of the Invasive Snail Species Potamopyrgus antipodarum (Mollusca, Gastropoda) – First Data for Bosnia and Herzegovina

Abstract

 Introduction: Potamopyrgus antipodarum (J. E. Gray, 1843) is an invasive freshwater and brackish water snail native to New Zealand, spreading across Europe since the 19th century. The first records in Bosnia and Herzegovina were published in 2005 in the Krivaja River. Later, the presence of this invasive snail species was also recorded in several springs of the rivers Bosna and Vrbas. Morphometric characteristics and fecundity are very important for a species’ adaptability and reproductive potential. These parameters have not previously been investigated in Bosnia and Herzegovina’s populations. 

Aim: To determine shell dimensions and the number of embryos of P. antipodarum from a selected spring on the right bank of the Vrbas River in Banja Luka, and to examine a possible relationship between shell size and fecundity. 

Materials and Methods: From the total number of individuals, 30 were randomly selected for morphometric analysis. After photographing each individual with a Leica EZ4D stereomicroscope, 
the following parameters were measured: total shell height, aperture height, total shell width, aperture width, and spire height above the aperture. Sex and number of embryos were determined for the same individuals. Descriptive statistics were performed. Pearson’s correlation coefficient (r) was calculated between total shell height and the number of embryos. 

Results:  The average value of total shell height was 4.03 ± 0.30 mm, total shell width 2.14 ± 0.17 mm, aperture height 1.49 ± 0.13 mm, and aperture width 1.28 ± 0.10 mm. The number of embryos varied from 13 to 36. The lowest coefficient of variation was observed for total shell height (7.44%), and the highest for the number of embryos (28.49%). A moderate positive correlation was found between shell size and number of embryos (r = 0.54), which suggests that larger individuals produce more embryos. 

Conclusion: The mean shell parameters and number of embryos fall within the known range. Fecundity of this invasive species increases with shell size.