New Zealand Journal of Marine and Freshwater Research abstracts
Predicting rates of primary production in the vicinity of the Subtropical
Convergence east of New Zealand
MARK GALL
IAN HAWES
National Institute of Water & Atmospheric
Research Ltd
P. O. Box 8602, Riccarton
Christchurch, New Zealand
email: m.gall@niwa.cri.nz
email: i.hawes@niwa.cri.nz
PHILIP BOYD
National Institute of Water & Atmospheric
Research Ltd
Centre for Chemical and Physical Oceanography
Department of Chemistry, University of Otago
Dunedin, New Zealand
email: p.boyd@niwa.cri.nz
Abstract Water column integrated productivity of
phytoplankton in three water masses east of New Zealand (Subtropical,
Subtropical Convergence, and Subantarctic) varied both seasonally and
spatially, ranging across two orders of magnitude. Productivity was highest in
spring and autumn, and lowest in winter. Subtropical and Convergence waters
were generally more productive than Subantarctic waters, but during summer the
2-3-fold range of production was similar in each of the three water masses.
Multiple regression analysis identified that most of the variability in
production was associated with differences in integrated chlorophyll
a
concentrations (56%). By considering both surface chlorophyll
a and
incident irradiance we derived a relationship which explained 74% of observed
spatial and seasonal variability in integrated production. These surface
variables can be sensed remotely, suggesting the potential for broad spatial
mapping of the seasonal cycles of production in these water masses in the New
Zealand Exclusive Economic Zone (NZEEZ). Further analysis of the relationship
identified that most of the remaining variability could be attributed to
(a temperature-dependent photoadaptive term). Exceptions to
the relationship and the application of productivity models within NZEEZ are
discussed.
Keywords photosynthesis; P-E; Subtropical Convergence;
modelling; New Zealand
M98042
Received 14 July 1998; accepted 9 March 1999
PDF file of entire paper: medium quality (1363K); (scanned from paper original: notes about this process)
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