Implications of bio-optical modeling of phytoplankton photosynthesis in Antarctic waters: Further evidence of no light limitation in the Bransfield Strait
Fg. Figueiras et al., Implications of bio-optical modeling of phytoplankton photosynthesis in Antarctic waters: Further evidence of no light limitation in the Bransfield Strait, LIMN OCEAN, 44(7), 1999, pp. 1599-1608
During the cruise ECOANTAR 94 photosynthesis versus irradiance relationship
s, phytoplankton spectral absorption, quantum yield of carbon fixation, and
water column Light regime were determined in the eastern Bransfield Strait
and surrounding areas of the Weddell Sea and Weddell-Scotia Confluence, to
determine if photosynthesis is Light Limited in these areas. There were no
significant differences in the light-saturated chlorophyll-specific rate o
f photosynthesis (P-m(B)), light-limited slope (alpha(B)), light saturation
parameter (E-kPAR), and the maximum quantum yield (phi(m)) between surface
and subsurface water for several water masses in the area, which indicates
that the photosynthetic response in the upper mixed layer was uniform. The
re were also no significant differences between the spectral light saturati
on parameter (E-kPAR) and the mean absorbed irradiance by phytoplankton in
the upper mixed layer (E-umlPUR). These similarities suggest that phytoplan
kton photosynthesis was not light limited in this Antarctic region during t
he cruise period. This was also affirmed by the fact that the average opera
tional quantum yield of the water column (0.03 mol C [mol photons](-1)) was
half of the mean maximum quantum yield (0.06 mol C [mol photons](-1)). Pri
mary production is underestimated by 24% when broadband models are compared
with spectral ones. These results have important implications for the mode
ling of carbon flows in the Southern Ocean.