New Zealand Journal of Marine and Freshwater Research abstracts
Vertical and horizontal structure of the picophytoplankton community in a
stratified coastal system off New Zealand
J. A. HALL
NIWA
P O Box 11-115
Hamilton, New Zealand
W. F. VINCENT
Département de Biologie
Université Laval
Québec G1K 7P4, Canada
Abstract The distribution of the picophytoplankton community
of the West Coast region of South Island, New Zealand, was investigated during
a period of thermal stratification in February 1989. The < 2 um size
fraction was found to account for a significant proportion of the plankton
biomass, with up to 73% of the particulate nitrogen and phosphorus occurring in
this size class. The spatial variability of the picophytoplankton community was
high with cell concentrations in the range 1.5-10.7 x 107 cells
l-1. The vertical distribution of cell numbers was highly variable,
although the maximum cell concentrations occurred in the mixed layer in all but
two of the 15 stations sampled. At these two stations the maximum cell
concentration coincided with the deep chlorophyll a maxima in the region
of the pycnocline. The composition of the picophytoplankton community was
highly variable with the P:E ratio ranging from 5.7 to 162 within the mixed
layer. Maximum concentration of eukaryotic cells occurred either just below or
just above the pycnocline where NO3 concentrations were elevated. This study
has illustrated the high degree of spatial variability in the composition of
the picophytoplankton population of the West Coast region. Some of this
variation can be attributed to physico-chemical environmental factors such as
nutrient supply impacting on growth rates.
Keywords Picophytoplankton; distributions; P:E ratios; New
Zealand.
New Zealand Journal of Marine and Freshwater Research, 1994: Vol. 28:
299-308
0028-8330/94/2803-0299 $2.50/0 (c) The Royal Society of New Zealand
1994
PDF file of entire paper: medium quality (710K); (scanned from paper original: notes about this process)
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