1993/01/01 by KD Lafferty · 2 citations
Environmental Science · #Marine and fisheries research #Parasite Biology and Host Interactions
paper · pdf · doi:10.3354/meps096229
openalex publication_date 1993/01/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/04
I investigated the prediction that parasitic castrators can reduce host population density. 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. Field experiments were conducted to determine the mechanisms by which larval trematodes might affect snail popula-tion~. Manipulations of snail density and trematode prevalence indicated that larval trematodes reduced the reproductive output of the snail population and caused differential mortality of parasitized hosts. Furthermore, an effect of competition between parasitized and unparasitized snails was detected by comparing snail growth rates. As expected, this was deemed to be a simple density effect and was not due to any special qualities of the parasitized snails. Analysis of chlorophyll a levels in the sediment suggested that competition may have occurred due to limited amounts of food. These results suggest that larval trematodes can reduce snail population densities by reducing snail reproduction, con~peting with parasitized snails for food and increasing the mortality rates of parasitized snails.