Dear Ranjeev,

I am not aware of any study comparing gastropod morphologies of rivers vs. lakes, but there are case studies dealing with phenotypic variability in each of both types (see PDFs and links below). However, I haven't found any significant differences between morphologies of the two environments. Exceptions might be the some patterns of morphological evolution in long-lived lakes, sometimes resulting in quite extraordinary phenotypes (e.g. West & Cohen 1994, Geary et al. 2002).

Best regards,

Thomas

further links:

http://link.springer.com/article/10.1007/s10750-008-9332-1

http://www.academia.edu/download/31488418/Kaek_River.pdf

I would add this one as well:

http://www.journals.uchicago.edu/doi/abs/10.1086/686912

Most of the lake v. river work has been done in freshwater mussels so you may want to look for those references as well. 

Ranjeev:

You may see this link as well:

Best

Syed

You can get full text from Researchgate of the paper Russ cited here:

https://www.researchgate.net/publication/297730617_Environmental_drivers_of_shell_shape_in_a_freshwater_gastropod_from_small_and_large_lakes

There is a fair amount of published literature on morphotypes in pleurocerid snails.  Russ has co-authored a lot of it.  You can check out some of the literature cited in my paper above.

Article Environmental drivers of shell shape in a freshwater gastrop...

Dear Dr. Neubauer, Dr. Minton, Dr. Jafar and Dr. Zanatta,

Thank you very much for the references. Some of these are my all time favorites. At interspecific level, I assumed that high spired morphotypes lacking shell ornamentations should dominate the fluvial settings whereas more depressed forms could occupy lacustrine habitats. Having said that, mainlining a high aperture length is important in fast flowing environment if the taxon does not  show any behavioral responses to high flow. As a researcher new to the field of freshwater molluscan ecology I found the reference below very detailed and intriguing, 

A treatise on limnology. V. 4. The zoobenthos. (G. E. Hutchinson).  Chapter 35

Thank you very much

Best,

Ranjeev