PARENT SESSION
Organized Oral Session 43: Complex consequences of spatial subsidies to food webs
Organizer(s): JM Kraus and WB Anderson
Thursday, August 11, 8:00 AM - 11:30 AM, Meeting Room 511 B, Level 5, Palais des congrès de Montréal

Dynamic food webs: Spatio-temporal variation in community structure and species interactions along the upper San Pedro River.

Soykan, Candan¹, Sabo, John¹, ¹ Arizona State University - Main Campus, Tempe, AZ

ABSTRACT- While theory traditionally regards food webs as static in both space and time, increasing evidence from empirical studies across a range of systems suggests otherwise. As a case in point, we have been studying community structure and species interactions along a gradient of water availability from the riparian forest that lines the banks of the San Pedro River to upland habitats characterized by Chihuahuan desert scrub. Specifically, we have measured arthropod and small mammal diversity in riparian, near desert scrub, and far desert scrub habitats across different seasons. Additionally, we have monitored seasonal changes in the distribution and diets of mammalian carnivores. Results from pitfall samples of arthropods indicate marked spatio-temporal variation in community structure. Small mammal community structure also varies among habitat types, with seasonal differences in fecundity and mortality. In turn, the distribution and diets of mammalian carnivores reflect changes in prey communities. Together, these data indicate a dynamic food web with complex spatio-temporal subsidies. The implications for communities in each habitat type are potentially profound, with opportunities for indirect effects across space and time. Given the ubiquity of spatial and temporal subsidies in natural communities, these results suggest a need to revise food web theory to include a dynamic perspective on ecological communities.

Key words: Food Webs, Community Structure, Indirect Effects