Phytoplankton biomass and photosynthetic competency in the summertime Mertz Glacier Region of East Antarctica
Vertical profiles of water temperature, salinity, beam transmission, density, pressure, wind speed, wind direction, phytoplankton biomass (chlorophyll a (Chl a) plus phaeophytin a), and photosynthetic competency (by fast repetition-rate fluorometry) are presented for the Mertz Glacier region, East A...
| Main Authors: | , , , |
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| Other Authors: | |
| Format: | Text |
| Language: | English |
| Published: |
2003
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| Subjects: | |
| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.521.1212 http://www.ldeo.columbia.edu/~vaillanc/Mertz_DSRII1355.pdf |
| Summary: | Vertical profiles of water temperature, salinity, beam transmission, density, pressure, wind speed, wind direction, phytoplankton biomass (chlorophyll a (Chl a) plus phaeophytin a), and photosynthetic competency (by fast repetition-rate fluorometry) are presented for the Mertz Glacier region, East Antarctica, for a 3-week period during the austral summer 2000–2001. Injection of low-salinity water from the melting of the ice pack formed a shallow (ca. 25m) mixed layer offshore. Two distinct deep mixing features were observed associated to varying degrees with high chlorophyll levels and high photosynthetic competency. Along the Adelie Land coast, a deep mixing layer (1400m) with Chl a concentrations of 386mgm2 and elevated Fv=Fm (>0.5) was observed. At the eastern end of the study area, along a seaward extension of fast-ice, a bloom of Phaeocystis antarctica bloom formed within a shallow (24m) mixed layer, with surface Chl a concentrations of ca. 8mgm3 and elevated Fv=Fm (0.5). This feature also had high surface salinity (>34) and was contiguous with a deep-mixing feature (236m). FRRF parameters Fv=Fm and sPSII were strongly suppressed in surface waters (o20m). Results of photoinhibition experiments showed that the photo-suppression of Fv=Fm and sPSII in surface waters was reversible over a time period of minutes to hours and suggested that the surface suppression was due to non-photochemical quenching by photo-protective pigments and photo-damage to Photosytem II reaction centers and pigment beds. FRRF data at a depth of 45–55m were independent of irradiance, and provided a reasonable |
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