New Zealand Journal of Marine and Freshwater Research abstracts

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Annual contribution of terrestrial invertebrates to a New Zealand trout stream

ERIC D. EDWARDS
ALEXANDER D. HURYN

Department of Zoology
P.O. Box 56
University of Otago
Dunedin, New Zealand

Abstract  Whole-stream drift from stream reaches enclosed by 1 mm mesh barriers was sampled to estimate the potential contribution of terrestrial invertebrates to trout production in a high-country pasture stream in New Zealand. Invertebrates were classified into two activity groups: winged or wingless. Biomass of winged insects was significantly related to temperature but not discharge. Biomass of wingless invertebrates was not related to temperature or discharge; however, abundance was significantly related to discharge but not temperature. These results suggest that mode of entry differed between activity groups. Winged insects apparently entered the stream as a function of overall activity, whereas wingless invertebrates entered the stream passively--possibly a result of fluctuations in discharge. An empirical model based on these relationships indicated that total input of terrestrial invertebrates may support as much as 5% of annual production by resident brown trout.

Keywords  terrestrial invertebrates; trout; diet; secondary production; Allen Paradox; streams; riparian zone; land-water interactions; New Zealand

New Zealand Journal of Marine and Freshwater Research, 1995: Vol. 29: 467-477

0028-8330/95/2904-0467 $2.50/0 (c) The Royal Society of New Zealand 1995

PDF file of entire paper: medium quality (833K); (scanned from paper original: notes about this process)

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