Our laboratory is engaged in four interlocking areas of research. The underlying theory being developed in our lab concerns the nature of adaptive peaks for different types of trophic interactions (links in the food web; predator/prey, parasite/host). This theory expands the concept of parasitic castration as a distinct type of trophic phenomenon. In our lab, this work has had many spin-offs concerning interactions between larval trematodes, the impact of parasites on fisheries, and the development of biological control for marine pests, as well as human schistosomaisis. Most of our field work is done in salt marshes using a speciose guild of larval trematode parasitic castrators. These parasitic castrators are strong interactors in the snail first intermediate host. Thus, we are examining the relationship between the parasites in the first and second intermediate hosts. The relative vagility of the second intermediate host effectively integrates the spatial patches of the first intermediate host.