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Communication at the NABS Annual meeting, Keystone, 2000
(111) THE INFLUENCE OF FLOODPLAINS ON SOURCES OF ORGANIC
MATERIAL AND NITROGEN FOR RIVER ORGANISMS -- DOES
FLOODPLAIN SIZE AND LOCATION MATTER?.
R.H. Riley1, A.D. Huryn2, R. Young3, C. Arbuckle1, K.A. Peacock1, and C.R. Townsend1. 1Department of Zoology, University of Otago, Dunedin, New Zealand, 2Department of Biological Sciences, University of Maine, Orono, ME
USA, 3Cawthron Institute, Nelson, New Zealand
We investigated the assimilation of terrestrial versus aquatic sources of carbon and nitrogen by macroinvertebrates and fish in constrained and unconstrained (floodplain) reaches of the Taieri River, New Zealand. Previous research indicated a strong influence of a large floodplain on sources of carbon and nitrogen used by aquatic consumers. In this study, we sampled at a finer spatial-scale to determine whether smaller floodplains had a similar influence, and we examined how quickly this influence is established within floodplain reaches. The study area included 30 km of the Taieri River (4th order) that began with constrained headwater reaches, passed through several small and one medium-sized floodplain and ended in a large floodplain. Macroinvertebrates and fish in floodplain reaches assimilated a greater proportion of terrestrial carbon than did organisms in constrained reaches upriver of the floodplains. This included some (but not all) organisms in small and medium-sized floodplains as well as the large floodplain. Assimilation of terrestrial carbon did not appear to decline in constrained reaches between floodplain reaches. Increased assimilation of terrestrial carbon by many organisms was established quickly as the river entered floodplain reaches, suggesting that processes underlying this phenomena operate over a relatively small scale
Presented at 10:45 AM on Tuesday, May 30, 2000 in River - Floodplain Interactions
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