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The natural diet of the Argentinean endemic snail Chilina parchappii (Basommatophora : Chilinidae) and two other coexisting pulmonate gastropods

2002; California Malacozoological Society; Volume: 45; Issue: 1 Linguagem: Inglês

0042-3211

Alejandra L. Estebenet, Néstor J. Cazzaniga, N. V. Pizani,

Mollusks and Parasites Studies

In this paper we study the natural diet of Chilina parchappii (d'Orbigny) (Chilinidae), Biomphalaria peregrina (d'Orbigny) (Planorbidae), and Physa venustula Gould (Physidae) in an artificial canal in the Province of Buenos Aires, Argentina. The close similarity between the organic particle composition of the sediment and the crop contents of the three species studied suggests they are basically non-selective feeders. The food composition does not differ from the Aufwuchs composition. Diatoms and detritus particles are the main food items for the three species. Although there is a high degree of diet overlap among the three species, a principal component analysis revealed interspecific differences in diet. Biomphalaria peregrina is more detritivorous; Chilina parchappii ingests more diatoms; and Physa venustula consumes more non-filamentous algae. Experimental analysis of the ingestion, egestion, and assimilation rates, and the assimilation efficiency suggests that the endemic Chilina parchappii is subject to a probable risk of competition in a case of food shortage. However, competition among snails is highly improbable in the present area of sympatry, i.e., the lower basin of the Naposta Grande stream, which is rich in detritus.