New Zealand Journal of Marine and Freshwater Research abstracts
Inundated floodplain gravels in a stream with an unstable bed: temporary
shelter or true invertebrate refugium?
C. D. MATTHAEI*
C. R. TOWNSEND+
Department of Zoology
University of Otago
P. O. Box 56
Dunedin, New Zealand
*Present address: Department of Zoology, University of Munich
(LMU), Karlstr. 25, 80333 Munich, Germany.
email: matthaei@zi.biologie.uni-muenchen.de
Abstract At near-peak flow of a large flood in a New Zealand
stream, we took 10 Surber samples in calm, shallow areas of an inundated flood
plain. The next day, when discharge was still high enough to cause bed movement
in the main channel but the flood plain had dried out again, we collected 10
sediment samples in the dry flood plain. Invertebrate taxon richness in
during-flood samples was 83% of that found in the main channel after a period
of stable flow, and total invertebrate densities were 10% of densities during
stable conditions. Taxon richness, total densities, and densities of the four
taxa most common in the benthos of the river were significantly lower in the
dry flood plain than in during-flood samples, implying that many invertebrates
left these patches during drying. Nevertheless, mean total invertebrate
densities in the dry flood plain were still 37% of during-flood values. We
conclude that inundated floodplain gravels provided temporary shelter for lotic
invertebrates during the flood, but several animals were trapped as the flood
plain dried, and those that managed to return to the baseflow channel were
still exposed to bed-moving shear stresses. We doubt that floodplain gravels
can act as true invertebrate refugia in our study river, primarily because of
the unstable nature of its sediments.
Keywords stream ecology; disturbance; invertebrates; refugia;
floodplain gravels; streambed stability
+ Corresponding author.
M99006
Received 4 February
1999; accepted 3 August 1999
PDF file of entire paper: medium quality (1157K); (scanned from paper original: notes about this process)
This year's abstracts |
Journal home page |
All abstracts |
Publishing home page
