My research focuses on the spatial and temporal patterns of parasitism within and among host populations, and the mechanisms that determine these patterns. My research system involves a diverse guild of larval trematode parasitic castrators that utilize the snail, Cerithidea scalariformis, as their intermediate host. The distribution of these parasitic castrators in snail populations is strongly influenced by the distribution and abundance of wading birds and marsh mammals, which serve as final hosts. As primary mechanisms of parasite dispersal (on both local and regional spatial scales), final hosts create spatial heterogeneity of parasitism within snail populations. Further, the distribution of larval trematodes is also influenced by intraspecific competition among larval trematodes for snail hosts.
In collaboration with colleagues at the Smithsonian Institution, we have developed a long term (since 1993) data set to understand the role of parasitism on host population size and dynamics, testing the hypothesis that parasitism is density-dependent and therefore could regulate snail population size. In the near future, we expect to test for a relationship between snail density and parasitism among snail populations and years, and to determine how spatial heterogeneity (variation among sites) influences parasite community structure using mathematical models.
