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

Aquatic-terrestrial exchange down river networks.

Power, Mary^*,1, Finlay, Jacques², McNeely, Francis, Limm, Mike, Rainey, William, ¹ Univeristy of California-Berkeley, Berkeley, CA² University of Minnesota, Minneapolis, MN

ABSTRACT- Significant exchange between terrestrial and river food webs is being established in rivers throughout the world. Terrestrial insects and plant material feed aquatic consumers; emerging aquatic insects are important resources for terrestrial consumers like lizards, spiders, and bats. Rates and net balances of river-watershed exchange vary down drainage networks in ways that may be partially predictable from mapped landscape characteristics. We will discuss environmental controls on cross habitat fluxes of terrestrial and aquatic insects and plant material at different positions (drainage areas from < 1 to > 270 km ² ) in the steep headwater drainage of the South Fork Eel River in north coastal California. Important primary factors that influence rates of resource production and fluxes include channel steepness, valley cross section, and vegetation structure. These habitat characteristics also influence resource tracking by aquatic and terrestrial consumers. Bats are the most mobile and voracious aquatic insectivores feeding over channels in our study sites. Bat foraging intensity increases downstream and species representation changes as vegetative structure opens, aquatic productivity rises, emergent insect taxa and size spectra shift, and water turbulence decreases.

Key words: cross-habitat exchange, river drainage networks, watershed food webs, river ecosystems