Abundance and Distribution of the Freshwater Snail Fauna in Comal Springs-Landa Lake, New Braunfels, Comal Co., Tx.




Cauble, Mary Kathryn

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A study of the abundance and distribution of freshwater snails in Landa Lake-Comal River, New Braunfels, Comal County, Texas was conducted from February - June 1998. Study sites (23) were selected in both the lake proper and the associated spring runs. Each site was characterized by macrophyte type, substrate, water depth and water velocity at maximum plant height. Eight families and nine species of gastropods were collected during the survey. Living specimens of Thiara granifera, Melanoides tuberculata, Cincinnatia comalensis, Marisa comuarietis, Elimia comalensis, Helisoma anceps and Hebetancylus excentricus were collected and shells of two additional gastropod species, Physella virgata and Pseudosuccinea columella were also found. Over 90% of the gastropods collected during the survey belonged to the family Thiaridae. The most abundant snail species found during the study was T. granifera. Over half of the living T. granifera found were collected from three· of the sample sites with densities reaching over 3,000/m2 in some areas of the lake. The second most abundant species collected, M. tuberculata, showed preferences for certain sample sites and was found to reach densities of more than 3,500 living M. tuberculata/m2 . Habitat preferences appear to be correlated with type of substrate, water velocity, presence and/ or type of macrophyte present, and proximity to springs and seeps.



snails, Comal River


Cauble, M.K. (1998). Abundance and distribution of the freshwater snail fauna in Comal Springs-Landa Lake, New Braunfels, Comal Co., Tx.(Unpublished thesis). Southwest Texas State University, San Marcos, Texas.


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