Detrital Chemistry, Growth, and Food Choice in the Salt‐Marsh Snail (Melampus Bidentatus)

Abstract

Chemical properties of detritus including its phenolic and nitrogen contents affect its palatability to the salt—marsh snail, Melampus bidentatus (Gastropoda: Pulmonata). We determined if chemical cues that enhance palatability also promote growth. Snails were reared in the laboratory on four diets of Spartina alterniflora detritus that differed in chemical composition. Laboratory growth was highest on a diet with lowest phenolic content; an increase in phenolic content resulted in a decrease in growth. Percent nitrogen, C:N ratio, and available nitrogen were not correlated with growth. Laboratory growth rates were similar to field rates. This suggests that laboratory diets resembled what snails found in the marsh and that chemical cues that control laboratory growth have relevance for field populations of snails. Phenolic content of detritus, therefore, controlled both palatability and growth. A decrease in phenolic content enhanced palatability of detritus to snails. Feeding on the detritus with the lowest phenolic content provided adequate nutrition to support growth.