PARENT SESSION
Oral Session #65: Aquatic Ecology: Stream and Lake.
Presiding: C. Osenberg
Wednesday, August 7. 1:00 PM to 4:45 PM. Coconino Meeting Room, TCC.
Modeling linkages between terrestrial and aquatic ecosystems (part II).
Kaplan, Isaac*,1, Roth, Brian1, Havlicek, Tanya1, Johnson, Pieter1, Sass, Gregory1, Carpenter, Stephen1, 1 University of Wisconsin-Madison, Madison, WI
ABSTRACT- This is the second of two presentations that examine the influence of coarse woody debris inputs and removals on fish food webs. Coarse woody debris in lakes increases the ability of fish prey to hide from their predators, and also provides substrate for benthic invertebrate prey. In this modeling study, we wished to determine which fish trophic levels are affected the most by changes in coarse woody debris density, and whether pulse vs. press alterations in coarse woody debris density have larger effects. In addition, we searched for depensatory dynamics at low fish biomass, and for the effect of harvesting on thresholds caused by depensation. To answer these questions we linked a biomass dynamics model of an aquatic food web to a riparian forest model, and subjected the system to perturbations similar to wind events (blow-downs) and human development of the lakeshore. The aquatic model was parameterized using data from Little Rock Lake in northern Wisconsin, and its resident insectivore (yellow perch Perca flavescens) and piscivore (largemouth bass Micropterus salmoides). Our results suggest that insectivore populations are impacted more than piscivores by changes in coarse woody debris. Moderate declines in wood availability caused by development of the shoreline had much larger impacts on fish communities than did extreme pulse events such as clear-cutting or wind events. The effects of these terrestrial pulse events on fish were reduced because of slow decay rates of coarse woody debris in the modeled lake.
KEY WORDS: food web, coarse woody debris, lakes, modeling