Document: MAI-3-51-14

Consequences of habitat size on the trophic structure and predator composition of an assemblage of arthropods in a sensitive salt marsh habitat.

MILLER, M.E.*, R.DENNO and C.GRATTON

University of Maryland, College Park, MD 20742, USA ¹

Abstract:
As humans continue to fragment the landscape, habitats that are occupied by invertebrate and vertebrate species become smaller and more isolated. For many species of small arthropods, locating and remaining in small habitats is difficult, as evidenced by their rarity in such habitats. However, little is known concerning the responses of predators to reduced patch size, and less yet is understood about the effects of habitat fragmentation on the trophic structure of a community. We examined the effect of habitat size on the density of herbivorous insects (planthoppers and leafhoppers) and their arthropod predators (spiders and heteropterans) on a mid-Atlantic salt marsh. Results show that with a decrease in patch size, two herbivorous species (Tumidagena minuta and Aphelonema simplex) decreased in abundance. Generalist predators, such as spiders, showed no significant differences in density as patch size decreased. However, specialized egg predators (heteropterans) decreased in abundance as habitat size decreased. This altered trophic structure on small patches may enhance the probability for extinction and promote unstable predator-prey dynamics.

Keywords: fragmentation; patch size; generalist-specialist; predator-prey; herbivores

This abstract is being presented at: 10:30 AM in session:
Poster Session #9: Fish, Lakes, Streams and Wetlands.