New Zealand Journal of Marine and Freshwater Research abstracts
M99066Received 8 November 1999; accepted 22 June 2000
Short communication
Influence of the small intertidal seagrass Zostera novazelandica on
linear water flow and sediment texture
WIEBKE M. HEISS
ABIGAIL M. SMITH
P. KEITH PROBERT
Department of Marine Science
University of Otago
P. O. Box 56, Dunedin
New Zealand
Abstract The influence of a small intertidal seagrass,
Zostera novazelandica (Setchell), on tidal current velocities and
sediment texture was studied at Harwood, Otago Harbour, New Zealand. Tidal
current velocities were substantially reduced inside the
Z.
novazelandica patch compared to velocities above the patch (3.7 times
greater) and outside it (2.5 times greater), causing a low-flow environment
among the 12-cm-tall seagrass. Current velocities combined over one tidal cycle
occupied a much wider range outside (1.2-4.6 cm s
-1) and above
(1.9-7.1 cm s
-1) the seagrass patch than inside
(0.1-1.8 cm s
-1) indicating slower and less variable water
flow. Suspended mud (<0.063 mm) settled to the bottom in this
low-energy environment and was protected from resuspension by seagrass cover,
indicated by significantly elevated amounts of mud inside the seagrass patch
(1.1%) compared to outside (0.4%). These results indicate that
Z.
novazelandica may reduce water flow and accumulate finer sediment sizes to
a lesser extent than larger subtidal seagrass species.
Keywords Zostera novazelandica; seagrass; eelgrass;
current velocity; flow reduction; sedimentation
New Zealand Journal of Marine and Freshwater Research, 2000, Vol. 34:
695-717
0028-8330/00/3404-0695 $7.00 (c) The Royal Society of New Zealand
2000
PDF file of entire paper: medium quality (439K); (scanned from paper original: notes about this process)
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