Nutrients in the Southern Ocean GLOBEC region: variations, water circulation, and cycling

Serebrennikova, Yulia M.; Fanning, Kent A.

doi:10.1016/j.dsr2.2004.07.023

Cited by 47 publications

(52 citation statements)

References 31 publications

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“…These relatively low values agree quite well with NCPs computed from surface layer deWcits along the coasts of Enderby Land and Wilkes Land in East Antarctica (Ishii et al 1998) and in the Scotia Sea (Shim et al 2006). On the other hand, across the Ross Sea including the Ross Sea Polynya (Sweeney et al 2000), and in the Gerlache Strait west of the Antarctic Peninsula (Karl et al 1991;Serebrennikova and Fanning 2004), much higher depletions and NCPs have been found.…”

supporting

confidence: 74%

Whole season net community production in the Weddell Sea

et al. 2007

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Depletions of total CO 2 , nitrate, phosphate and silicate in the surface layer were calculated for cruise ANT XXII/3 with FS Polarstern in March 2005 for estimating the annual net community production. East-west across the Weddell Sea the variation of all depletions is similar, but this holds to a lesser extent for silicate. Depletions in March 2005 are 2-3 times larger than those in January 1993 for the same transect. Very low N:P and C:P depletion ratios seem to point to dominance of diatoms, in the central Weddell Sea more than in the margin. Estimates of annual net community productions are about 1.8 and 3.5 mol C m ¡2 year ¡1 for the interior Weddell Sea and a near-margin region, respectively. The region does not comply with the classical view of a marginal ice zone with high productivity. Net community production is similar to annual export production, implying that remineralization in the ensuing winter be minor.

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confidence: 74%

Whole season net community production in the Weddell Sea

et al. 2007

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“…While positive net community production decreases DIC, the biological effect of organic matter production on TA depends on the source of nitrogen, where nitrate consumption increases TA and ammonium consumption decreases TA (Goldman and Brewer, 1980). Since nitrate is more abundant than ammonium in WAP surface waters (Serebrennikova and Fanning, 2004), nitrate was assumed as the nitrogen source. With a Redfield stoichiometry of 6.6 mol C mol N −1 , TA should increase by 1/6.6 = +0.15 µmol TA per µmol DIC consumed.…”

Section: Physical and Biological Drivers Of The Inorganic Carbon Systemmentioning

confidence: 99%

Two decades of inorganic carbon dynamics along the West Antarctic Peninsula

et al. 2015

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Abstract. We present 20 years of seawater inorganic carbon measurements collected along the western shelf and slope of the Antarctic Peninsula. Water column observations from summertime cruises and seasonal surface underway pCO 2 measurements provide unique insights into the spatial, seasonal, and interannual variability in this dynamic system. Discrete measurements from depths > 2000 m align well with World Ocean Circulation Experiment observations across the time series and underline the consistency of the data set. Surface total alkalinity and dissolved inorganic carbon data showed large spatial gradients, with a concomitant wide range of arag (< 1 up to 3.9). This spatial variability was mainly driven by increasing influence of biological productivity towards the southern end of the sampling grid and meltwater input along the coast towards the northern end. Large inorganic carbon drawdown through biological production in summer caused high near-shore arag despite glacial and seaice meltwater input. In support of previous studies, we observed Redfield behavior of regional C / N nutrient utilization, while the C / P (80.5 ± 2.5) and N / P (11.7 ± 0.3) molar ratios were significantly lower than the Redfield elemental stoichiometric values. Seasonal salinity-based predictions of arag suggest that surface waters remained mostly supersaturated with regard to aragonite throughout the study. However, more than 20 % of the predictions for winters and springs between 1999 and 2013 resulted in arag < 1.2. Such low levels of arag may have implications for important organisms such as pteropods. Even though we did not detect any statistically significant long-term trends, the combination of ongoing ocean acidification and freshwater input may soon induce more unfavorable conditions than the ecosystem experiences today.

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“…Looking at the relative abundances of different types of phytoplankton, Prézelin et al (2004) noticed that off the west coast of Adelaide Island, diatoms dominated over phytoflagellates, while near the coast there was co-dominance of these two groups. Diatoms tend to dominate in environments where there is sufficient supply of silica-rich water, as is the case with the oceanic water intrusions studied in Chapter 4 (Prézelin et al, 2000;Serebrennikova and Fanning, 2004). This suggests that the APCC front, which separates the relatively fresh, presumably silica-poor water near the shore from the regions on the mid-shelf more likely to receive the high-silica intrusions, might create a favorable environment for phytoflagellates near the coast, by limiting the supply of silica to the diatom popula-…”

Section: Summary and Open Questionsmentioning

confidence: 99%

“…Chlorophyll (Dierssen et al, 2002), nutrient deficits (Serebrennikova and Fanning, 2004) and plankton concentrations Lawson et al, 2004;Lawson, 2006) are high along the coast. This suggests that the APCC might be key to providing a favorable environment for biological production.…”

Section: Summary and Open Questionsmentioning

confidence: 99%

“…As the sea-ice retreats and later during the ice-free season, the surface mixed layer is partially restratified by surface heating and freshening by sea-ice melt and runoff. (Smith et al, 1999;Serebrennikova and Fanning, 2004). The north-south temperature gradient is likely a combination of the shelf-wide cooling during the four-week cruise, which proceeded from north to south , and a mean gradient reflecting the regional climate (Stammerjohn et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

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Ocean circulation and dynamics on the west Antarctic Peninsula continental shelf

Moffat¹

2007

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Observations of current velocity, temperature, salinity and pressure from a 2-year moored array deployment and four hydrographic cruises conducted by the United States Southern Ocean GLOBEC program on the western Antarctic Peninsula continental shelf are used to characterize the ocean circulation and its connection to fresh water and heat fluxes on the shelf. Mean velocities on the shelf are of the order of 5 cm/s or less. Tidal motions are dominated by the M 2 and S 2 semi-diurnal tides and the O 1 and K 1 diurnal tides, although the tidal velocities are typically less than 2 cm/s. Near-inertial motions are relatively large, with current velocities as high as 26 cm/s. It is shown that Marguerite Trough, a large bathymetric feature connecting the shelf-break to Marguerite Bay, plays a critical role in determining the circulation. The mean flow is strongly steered in the along-slope direction, and the tidal currents also show increasing current polarization at depth in Marguerite Trough. At timescales of 5 to 20 days, the observations show bottom-intensified motion in Marguerite Trough consistent with bottom-trapped topographic Rossby waves. The subtidal circulation in the trough has a significant wind-driven component in Marguerite Trough, with downwelling-favorable winds forcing cross-shelf flow on the northern side of the trough and along the shore on the outer shelf. Upwelling-favorable winds force roughly the opposite circulation. The cyclonic circulation on the trough helps advect blobs of salty, warm and nutrient-rich water across the shelf. These intrusions are small (≈4 km) and frequent (4 events/month). Also, the Antarctic Peninsula Coastal Current (APCC), a coastal buoyant current which is described for the first time here. The APCC is a seasonal current which is only present during the ice-free season and is forced by freshwater fluxes associated with large glacier melt and precipitation rates in the region. This section would be in danger of becoming a Chapter were I to list all of the good friends I've met here. But! Special mention to the PO crowd:

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Nutrients in the Southern Ocean GLOBEC region: variations, water circulation, and cycling

Cited by 47 publications

References 31 publications

Whole season net community production in the Weddell Sea

Whole season net community production in the Weddell Sea

Two decades of inorganic carbon dynamics along the West Antarctic Peninsula

Ocean circulation and dynamics on the west Antarctic Peninsula continental shelf

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