PARENT SESSION
Tuesday, August 8, 1:30-5:00 pm
COS 39 - Community ecology II: community dynamics and change
L-3, Lobby Level, Cook Convention Center
Presiders: K Beard and Y Wang
Indirect effects of nutrient inputs and detritus on the structure and composition of terrestrial arthropod communities.
Wimp, Gina*,1, Finke, Deborah2, Denno, Robert1, 1 University of Maryland, College Park, MD, U.S.A.2 Washington State University, Pullman, WA, U.S.A.
ABSTRACT- Allocthonous inputs of nutrients into ecosystems can shape arthropod diversity and community structure in a diversity of ways. Greater productivity via nutrient input can: (1) increase both the total abundance and number of arthropod species that the host plant is able to support, (2) alter species interactions and thereby affect arthropod species composition, and (3) modify food chain length by increasing basal resources and increasing the efficiency of energy transfer among trophic levels. Moreover, natural variation in detritus can dramatically alter aboveground arthropod species interactions. Thus, we examined the effects of a nutrient subsidy and leaf litter on arthropod communities in an intertidal marsh system dominated by the cordgrass Spartina alterniflora, a system that receives regular nutrient inputs from neighboring upland and marine habitats. We designed a 2 x 3 factorial experiment (three levels of nitrogen subsidy and two levels of detritus) to test the effects nitrogen subsidies and their interaction with detritus on the associated arthropod community. We found an increase in arthropod species richness and abundance in response to both fertilization and detritus addition. Additionally, there was a significant difference in arthropod community composition among different fertilization and detritus treatments. Last, we found a significant increase in food chain length with increasing levels of fertilization. These results have important conservation implications in wetlands ecosystems which are experiencing increased nutrient runoff due to anthropogenic activity, and where such changes in arthropod community composition and trophic structure feedback to influence nutrient cycling and productivity.
Key words: arthropod community ecology, allocthonous nutrients, intertidal salt marsh