New Zealand Journal of Marine and Freshwater Research abstracts
Sedimentary record of radiolarian biogeography, offshore eastern New
Zealand
C. J. Hollis
Institute of Geological and Nuclear Sciences
P.O. Box 30 368
Lower Hutt, New Zealand
email: c.hollis@gns.cri.nz
H. L. Neil
National Institute of Water and Atmospheric
Research Limited
P.O. Box 14 901, Kilbirnie
Wellington, New Zealand
Abstract Examination of 38 surface sediment samples
from offshore eastern New Zealand, between 33°S and 54°S, yielded
100 radiolarian taxa, which are common to abundant in sediments deposited
at >1000 m water depth but rare at shallower depths. In general, radiolarians
are most abundant, most diverse, and best preserved in assemblages north
of the Subtropical Front (STF). Multivariate analysis of census data for
29 radiolarian-rich samples identifies six sample groups and eight species
groups. The STF forms a major biogeographic barrier, separating three transitional
zone (TR) and three subantarctic zone (SA) sample groups. The three primary
sample groups (TR1, TR2, SA1) record a southward latitudinal trend of decreasing
abundance of subtropical-tropical or warm-water taxa (species group 4) and
increasing abundance of subantarctic-Antarctic or cool-water taxa (species
groups 7 and 8). Two secondary sample groups (TR3 and SA2) may record the
influence of shallow-water processes or strong surface currents on either
side of the STF. A distinctive sample group (SA3), characterised by low abundance
and diversity, records relatively shallow, stratified, and silica-limited
conditions of the central Campbell Plateau.
Keywords radiolarian; Protista; Subtropical Front; transitional
zone; subantarctic zone; multivariate analysis
M04130; Online publication date 18 February 2005
Received 5 August 2004; accepted 9 November 2004
New Zealand Journal of Marine and Freshwater Research, 2005, Vol. 39:
165–192
0028-8330/05/3901-0165 © The Royal Society of New Zealand 2005
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