Growth and fecundity of Pomacea patula (Caenogastropoda: Ampullariidae) when fed on gel diets of Scenedesmus incrassatulus (Chlorophyceae)

Abstract

The commercial capture of Pomacea patula ("tegogolo" or "apple snail") in Catemaco Lake, Veracruz, Mexico, has decreased considerably in recent years. Its conservation and continued use as a regional economic resource is threatened, because little biological-ecological information is known for the species and measures regulating the intensity of its exploitation are deficient. As a contribution to the biological knowledge of this mollusk, the present study evaluates the effect of diet on P. patula growth and reproduction in laboratory. Two types of diet were applied, each gelled with 8% cornstarch, and containing varying proportions of the microalga Scenedesmus incrassatulus (Chlorophyceae). Diet 1 contained 100% microalgae, whereas in diets 2, 3, and 4, S. incrassatulus was gradually substituted with balanced trout food in proportions of 10%, 20%, and 40% dry weight, respectively. After twelve months of observation, no significant differences in growth, as measured by size and weight, were noted (P < 0.05). All experimental mollusk populations reached sexual maturity at six months of age, and fecundity was higher when the proportion of balanced food in the diet was increased. Survival during the observation period fluctuated between 70% and 85% regardless of diet.

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