During austral summer 1996, thirty-eight hydrological stations were sampled within 72°-78° S and 164°-175° W in the Ross Sea. In the open sea integrated Chl-a concentrations were between 15 and 102 mg/m2 in the 0-100 m layer and primary production was between 124 and 638 mgC/(m2d). Phytoplankton biomass and production were relatively high wherever the Upper Mixed Layer (UML) was <30m deep. Along coastal waters of Terra Nova Bay, during a late summer bloom, integrated primary production ranged between 620 and 2411 mgC/(m2d). Dimensional composition of phytoplankton and the Redfield ratio indicate that the Ross Sea was dominated by diatoms. The photosynthetic parametrs measured suggest the importance of the depth and dynamics of the UML where the integrated mean irradiance always exceeded the photosaturation index Ek. However, occasionally different P(Bmax) and Ek were recorded even in apparently well-mixed water column. The presence of turbolent cell in different layers of the photic zone or a weak wind-driven vertical mixing, which might induce different photosynthetic indexes can thus be hypothesized. Simulated in situ primary production was well correlated with production calculated with the photosynthetic coefficients obtained from the P vs. E experiments. Our data could be used to construct models aimed at assessing primary production in the area studied.
Primary production in ice-free waters of the Ross Sea (Antarctica) during the austral summer 1996
2002
Abstract
During austral summer 1996, thirty-eight hydrological stations were sampled within 72°-78° S and 164°-175° W in the Ross Sea. In the open sea integrated Chl-a concentrations were between 15 and 102 mg/m2 in the 0-100 m layer and primary production was between 124 and 638 mgC/(m2d). Phytoplankton biomass and production were relatively high wherever the Upper Mixed Layer (UML) was <30m deep. Along coastal waters of Terra Nova Bay, during a late summer bloom, integrated primary production ranged between 620 and 2411 mgC/(m2d). Dimensional composition of phytoplankton and the Redfield ratio indicate that the Ross Sea was dominated by diatoms. The photosynthetic parametrs measured suggest the importance of the depth and dynamics of the UML where the integrated mean irradiance always exceeded the photosaturation index Ek. However, occasionally different P(Bmax) and Ek were recorded even in apparently well-mixed water column. The presence of turbolent cell in different layers of the photic zone or a weak wind-driven vertical mixing, which might induce different photosynthetic indexes can thus be hypothesized. Simulated in situ primary production was well correlated with production calculated with the photosynthetic coefficients obtained from the P vs. E experiments. Our data could be used to construct models aimed at assessing primary production in the area studied.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
