Effects of experimental inundation on a coastal salt marsh trophic network

Coastal marshes are intermittently subjected to flooding which varies in intensity and duration. The physiological impact of inundation stress has been characterized for many salt marsh plants; it is not known how flooding affects the invertebrate assemblages that these plants support, though marsh invertebrates may be behaviorally or physiologically plastic as an adaptation to a variable environment. There may be short-term direct effects on insects, or prolonged indirect effects mediated by host plant physiological responses to flooding. Spartina patens, the dominant plant in our experimental plots, is fed upon by several guilds of herbivores, which in turn support an assemblage of predators, parasites and parasitoids. We experimentally flooded 3m2 enclosures on a brackish coastal marsh in Louisiana. Insects were collected from treatment and control plots and their taxonomic identity and feeding guild were recorded. Spartina patens was also collected and nutritional value and palatability of plant tissues were measured and compared between plots. Pathway analysis was used to determine the effects of flooding on plant quality and the magnitude of direct and indirect effects of flooding on the species richness and abundance of insects. This project emphasizes the value of a multitrophic perspective when examining the impact of environmental stressors on an ecosystem.