Aquatic Sciences Meeting, Albuquerque 2001

CS34 Trophic Dynamics

Date: Friday, February 16, 2001, Time: 8:45:00 AM

Location: Mesilla

Luecke, C, , Utah State University, Logan, USA, luecke@cnr.usu.edu

Burkart, G, , Utah State University, Logan, USA, greta@cc.usu.edu

USING STABLE ISOTOPES TO ASSESS PATTERNS OF ENERGY FLOW IN ARCTIC LAKE FOOD WEBS

Lake food webs in the arctic are based on relatively simple communities with few species of crustaceans, insects, and fish. We used this simplicity to investigate patterns of trophic transfer in lakes with differing types of food webs by measuring the ratio of stable isotopes of carbon and nitrogen in lake organisms. Carbon stable isotopes provided information on the degree to which a consumer acquired energy from pelagic versus benthic resources. Nitrogen provided information about the trophic level occupied by that organism. Omnivorous species such as calaniod copepods and salmonid fishes were most variable across food webs. Our results indicated that lake trout derived over 80% of their energy from benthic sources, compared to less than 25% for arctic grayling. The trophic level of omnivorous copepods varied consistently with food web structure.

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Aquatic Sciences Meeting, Albuquerque 2001

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