Document: BRA-3-73-18

Linking species behavior and ecosystem processes: Organism activity drives patterns of organic matter transport in streams.

TAYLOR, B.W.* ¹, A.S.FLECKER ¹, B.L.PECKARSKY ^1,2 and A.R.MCINTOSH ^2,3

Cornell University, Ithaca, NY 14853 USA ¹
Rocky Mountain Biological Laboratory, Crested Butte CO USA ²
University of Canterbury, Christchurch New Zealand ³

Abstract:
We asked whether behavioral activity of organisms affects ecosystems processes. In neotropical streams with a diverse community of benthic-feeding fish, we examined the influence of fish activity on the diel pattern of organic matter transport in the natural stream, in experimental channels, and using particle surrogates released into the stream. In Rocky Mountain streams, we examined the influence of invertebrate behavior on organic matter transport in streams with and without predatory trout, in flow-though channels with chemical cues from trout added, and in whole-stream manipulations in which chemical cues were also added. In neotropical streams, organic matter transport remained low during early morning hours, increased significantly during afternoon, and peaked in late evening. Field patterns of fish activity and experimental results indicate that activity of diurnal and nocturnal fish is correlated with organic matter transport. In the Colorado study, streams with trout had low transport during the day when the risk of fish predation was high. In contrast, greater transport was observed at night when invertebrate activity was highest and risk to fish predation was low. In fishless streams, invertebrate activity was aperiodic and transport did not change over 24 hours. Multiple years of data from the Venezuelan system suggest that fish have strong effects on the transport of organic matter dynamics through consumption and behavioral mechanisms. In the Colorado system, with an additional trophic level (predators), we observed cascading effects of predators on species behavior that indirectly affected the ecosystem process of organic matter transport.

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This abstract is being presented at: 9:00 AM in session:
Oral Session #70: Aquatic Ecology.