Effect of calcium concentration on growth and egg laying of Helisoma duryi, Biomphalaria alexandrina, B. camerunensis and Bulinus truncatus (Gastropoda: Planorbidae).

Published online
19 Apr 1988
Content type
Journal article
Journal title
Journal of Applied Ecology

Madsen, H.

Publication language


In order to evaluate the potential of H. duryi to establish populations in schistosomiasis endemic areas, the response of H. duryi to calcium concentrations ranging from 0.00 to 2.00 msmallcap˜M was compared with that of Biomphalaria alexandrina, B.camerunensis and Bulinus truncatus. Growth increased with calcium concentration up to 0.25-0.50 msmallcap˜M for H. duryi, Bulinus truncatus and Biomphalaria alexandrina; for B. camerunensis, concentrations >0.06 msmallcap˜M did not result in significantly increased growth over 10 weeks. The net reproductive rate after 10 weeks also increased with calcium concentration up to 0.13-0.25 msmallcap˜M in all the species except B. camerunensis, which showed smaller differences between the calcium treatments. All 4 species formed heavier shells at higher calcium concentrations. H. duryi caused greater calcium decrements in all test media than the other 3 species, and appeared to extract calcium more efficiently at lower calcium concentrations. Hatching of egg masses was unaffected by calcium concentration, except in the 0.00 msmallcap˜M treatment for B. alexandrina and B. camerunensis. Survival of newly hatched snails was high and was reduced in media with the lowest calcium concentrations.

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