SS3.18 Habitat Coupling in Lakes
Date: Thursday, June 13, 2002
Time: 12:00:00 PM
Location: Esquimalt
Vander ZandenMJ, University of Wisconsin - Madison, Madison, USA,
Essington, T, E, SUNY - Stony Brook, Stony Brook, USA,
Benthic energy flow and pelagic trophic cascades in lake food webs
In northern lakes, littoral zone piscivores (smallmouth bass, largemouth bass, and rock bass) often regulate the abundance and community structure of zooplanktivorous fishes; changes which often cascade down the food web to affect zooplankton and phytoplankton. A synthesis of dietary data and stable carbon isotope data for smallmouth, largemouth, and rock bass indicated that fish comprised a relative small part of their diet. Rather, all three species were omnivorous generalists, and benthic invertebrates were the dominant prey. This apparent uncoupling between energetics (a benthic diet) and dynamics (top down control in the pelagic) in these systems was further explored with a series of dynamic models comprised of a predator (bass) and two prey items (zooplanktivorous fish and zoobenthos). The models suggest that the levels of benthivory observed for bass tends to accentuate the top-down regulation of zooplanktivores. We suggest that the well-known trophic cascade in the pelagic zone of lakes is frequently subsidized by energetic inputs from benthic habitats.