THE CHEMICAL ECOLOGY OF BIOMPHALARIA GLABRATA: THE EFFECTS OF AMMONIA ON THE GROWTH RATE OF JUVENILE SNAILS

Abstract

Juvenile B. glabrata were subjected to NH3 concentrations ranging from 1-100 .mu.g/ml in various media. The addition of NH3 to borate buffered media caused mortality. Both borate and tris buffered media caused a decrease in the growth rate of snails when compared with controls in SSW [standard sea water]. The growth rates of the snails was enhanced by increasing the NH3 concentration to critical thresholds, but further increases beyond these thresholds resulted in growth inhibition. The toxicity of NH3 in ambient water was augmented by an increase in pH. The possible causes and ecological significance of these effects are discussed. The snails are probably physiologically well adapted to utilize NH3 when required and to control its excretion and uptake from the medium.