Effects of parasitic castration on growth, reproduction and population dynamics of the marine snail Cerithidea californica

Abstract

A survey of the salt marsh snail Cerithidea californica suggested a negative association between snail density and the prevalence of larval trematodes which castrate parasitized snails. Larval trematodes reduced the reproductive output of the snail population and caused differential mortality of parasitized hosts. An effect of competition between parasitized and unparasitized snails was detected by comparing snail growth rates. As expected, this was a simple density effect and was not due to any special qualities of the parasitized snails. Competition may have occurred due to limited amounts of food. Larval trematodes can reduce snail population densities by reducing snail reproduction, competing with parasitized snails for food and increasing the mortality rates of parasitized snails. -from Author