New Zealand Journal of Marine and Freshwater Research abstracts
Flow preferences of larval Chironomidae (Diptera) in Tongariro River, New Zealand
KEVIN J. COLLIER
Conservation Sciences Centre Department of Conservation P. O. Box 10-420 Wellington, New Zealand
Present address: NIWA Ecosystems, P. O. Box 11-115, Hamilton, New Zealand
Abstract
Flow preferences of five major chiro-nomid taxa
(Cricotopus, Orthocladiinae sp. a,
Eukiefferiella, Tanytarsus vespertinus, and
Maoridiamesa) were investigated in December 1990 at three sites in Tongariro River, central North Island, New Zealand. Exponential polynomial preference curves indicated that most taxa were found predominantly in water < 0.5 m deep when data from all sites were combined (range of conditions sampled = 0.1-1.5 m).
Cricotopus and Orthocladiinae sp. a appeared to have broad velocity preferences over the range sampled (0.1-1.8 m s"
1). In contrast,
T. vespertinus had a velocity optimum of 0.1 m s"
1, and
Maoridiamesa had an optimum > 1.0 m s
-1 at all sites. Abundances of
Eukiefferiella were greatest over an intermediate range of velocity conditions (0.7-1.5 m s~'). Mechanisms leading to differences in velocity optima amongst chironomid taxa may include differential oxygen requirements, and changes in food supply. When determining optimal minimum flows for benthic chironomid communities, it may be sufficient to focus on the requirements of taxa such as
Maoridiamesa and
Tanytarsus vespertinus which appeared to have well-defined and disparate velocity preferences in the main river.
Keywords Chironomidae; Tongariro River; Orthocladiinae; Diamesinae; Chironominae; flow preferences; New Zealand; streams
M92065
Received 9 December 1992; accepted 22 March 1993
New Zealand Journal of Marine and Freshwater Research, 1993: Vol. 27: The Royal Society of New Zealand 1993
Received 9 December 1992; accepted 22 March 1993
PDF file of entire paper: medium quality (596K); (scanned from paper original: notes about this process)
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