New Zealand Journal of Marine and Freshwater Research abstracts
Role of microzooplankton grazers in the subtropical and subantarctic waters
to the east of New Zealand
Julie Hall
Karl Safi
Andrea Cumming
National Institute of Water and Atmospheric
Research Limited
P.O. Box 11 115
Hamilton, New Zealand
email: j.hall@niwa.co.nz
Abstract Subtropical and subantarctic surface waters
to the east of New Zealand were sampled in four seasons over a period of 3
years to evaluate the importance of the microzooplankton as grazers of the
phytoplankton community. Subtropical waters (STW) to the north were warm with
high salinity and seasonal macronutrient limitation. Subantarctic waters (SAW)
to the south were colder, with lower salinity, high macronutrient concentrations
and chlorophyll a concentrations between 0.20 and 0.28 μg litre-1.
In the STW, phytoplankton showed a typical seasonal pattern for macronutrient-limited
waters, with biomass dominated by large phytoplankton and a chlorophyll a
maximum of 1.4 μg litre-1 in spring. Microzooplankton biomass varied
from 4.5 μg carbon (C) litre-1 in the STW in winter, to 13.8 μg
C litre-1 in the SAW in winter with the heterotrophic flagellates
contributing between 22% and 78% of the biomass. In spring and winter in
the STW, only 73% of the primary production was grazed by the microzooplankton
compared with over 100% in autumn and summer. In contrast, over 100% of the
primary production was consumed in all seasons by the microzooplankton in
SAW. In the SAW in all seasons and the STW in summer and autumn, microzooplankton
grazing on phytoplankton dominated the organic matter fluxes from the phytoplankton
population. During these periods the picophytoplankton contributed a significant
proportion of the phytoplankton biomass.
Keywords picophytoplankton; phytoplankton; microzooplankton;
grazing
M02069; Online publication date 15 March 2004; Received 2 September 2002;
accepted 25 November 2003
New Zealand Journal of Marine and Freshwater Research, 2004, Vol. 38:
91-101
0028-8330/04/3801-0091 © The Royal Society of New Zealand 2004
PDF file of entire paper: Print-quality (310K) |
screen-quality (133K)
This year's abstracts |
Journal home page |
All abstracts |
Publishing home page
