Microzooplankton herbivory in the Ross Sea, Antarctica

Caron, David A.; Dennett, Mark R.; Lonsdale, D; Moran, Dawn M.; Shalapyonok, Ludmilla

doi:10.1016/s0967-0645(00)00067-9

Cited by 153 publications

(132 citation statements)

References 47 publications

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“…A likely contributing factor to the biomass differences we observed is related to loss processes and the composition of the plankton community earlier in the season. In the Ross Sea, Phaeocystis antarctica tends to be important during the spring bloom (Arrigo et al, 1999;Caron et al, 2000); this species, which does not sink rapidly and, during its colonial life stage, may evade grazing by protozoa, was still present during our summertime sampling. Moreover, Caron et al (2000) reported that microzooplankton grazing rates were always low relative to phytoplankton growth rates during spring-summer 1996-1997 in the Ross Sea.…”

Section: Control Of Biomassmentioning

confidence: 97%

“…In the Ross Sea, Phaeocystis antarctica tends to be important during the spring bloom (Arrigo et al, 1999;Caron et al, 2000); this species, which does not sink rapidly and, during its colonial life stage, may evade grazing by protozoa, was still present during our summertime sampling. Moreover, Caron et al (2000) reported that microzooplankton grazing rates were always low relative to phytoplankton growth rates during spring-summer 1996-1997 in the Ross Sea. In contrast, large diatoms, which typically sink rapidly once nutrients are depleted, dominated during the bloom in the Polar Front region, but were not present in high abundances in late summer north of 651S (Landry et al, 2002).…”

Section: Control Of Biomassmentioning

confidence: 97%

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Phytoplankton and iron limitation of photosynthetic efficiency in the Southern Ocean during late summer

Sosik

Olson

2002

Deep Sea Research Part I: Oceanographic Research Papers

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As part of two USJGOFS cruises, we investigated spatial variability in phytoplankton properties across the strong environmental gradient associated with the Antarctic Polar Frontal Zone during late austral summers of 1997 and 1998. Cell properties, including size and an index of pigment content as well as photosynthetic efficiency (as indicated by relative variable fluorescence), changed dramatically across this frontal region. A general trend toward reduced photosynthetic efficiency south of the Polar Front was correlated with low dissolved iron concentration and is consistent with physiological iron limitation in the phytoplankton. We detected no significant differences in photosynthetic efficiency among different size classes of the dominant pico-to nanophytoplankton, despite a systematic community level shift toward larger sized cells south of the Polar Front. In contrast to other cells, those classified as cryptophyte algae showed relatively high photosynthetic efficiency in low iron waters; however, this group was never found in high abundance. One group, all cells p2 mm, showed an unexpected increase in intracellular pigment content (based on single cell chlorophyll fluorescence measurements) south of the Polar Front where dissolved iron concentration and the cells' relative abundance were low. Overall, these results suggest that group-or size-specific differences in physiological status were not directly regulating community structure in the pico-to nanophytoplankton during the late summer season; other processes, such as differential grazing or sinking losses, must be important.

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Section: Control Of Biomassmentioning

confidence: 97%

Section: Control Of Biomassmentioning

confidence: 97%

Phytoplankton and iron limitation of photosynthetic efficiency in the Southern Ocean during late summer

Sosik

Olson

2002

Deep Sea Research Part I: Oceanographic Research Papers

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“…N/ P removal ratios are low in austral spring, but increase with time, and over a season are close to the classical Red"eld ratio. E The massive phytoplankton blooms in the Ross Sea have essentially no losses due to microzooplankton herbivory regardless of the season (Caron et al, 2000). Microzooplankton biomass, however, increases three orders of magnitude over the seasonal cycle.…”

Section: Other 5ndings In Aesopsmentioning

confidence: 98%

The US Southern Ocean Joint Global Ocean Flux Study: an introduction to AESOPS

Smith

Anderson

Moore

et al. 2000

Deep Sea Research Part II: Topical Studies in Oceanography

120

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The United States Southern Ocean Joint Global Ocean Flux Study (JGOFS), also known as AESOPS (Antarctic Environment and Southern Ocean Process Study), focused on two distinct regions. The "rst was the Ross-Sea continental shelf, where a series of six cruises collected a variety of data from October 1996 through February 1998. The second area was the southwest Paci"c sector of the Southern Ocean, spanning the Antarctic Circumpolar Current (ACC) at &1703W. Data were collected within this region during "ve cruises from September 1996 through March 1998, as well as during selected transits between New Zealand and the Ross Sea. The "rst results of these cruses are described in this issue. The Ross-Sea investigation extensively sampled the area along 76330 S to elucidate the temporal patterns and processes that contribute to making this one of the Antarctic's most productive seas. Hydrographic distributions con"rm that strati"cation is initiated early in October within the polynya, generating an environment that is favorable for phytoplankton growth. Signi"cant spatial variations in mixed-layer depths, the timing of the onset of strati"cation, and the strength of the strati"cation existed throughout the growing season. Nutrient concentrations re#ected phytoplankton uptake, and reached their seasonal minimal in early February. Chlorophyll concentrations were maximal in early January, whereas productivity was maximal in late November, which re#ects the temporal uncoupling between growth and biomass accumulation in the region. Independent estimates of biogenic export suggest that majority of the #ux occurred in late summer and was strongly uncoupled from phytoplankton growth. The ACC region exhibited seasonal changes that in some cases were greater than those observed in the Ross Sea.0967-0645/00/$ -see front matter 2000 Published by Elsevier Science Ltd. PII: S 0 9 6 7 -0 6 4 5 ( 0 0 ) 0 0 0 5 9 -X Sea ice covered much of the region south of the Polar Front in winter, and retreated rapidly in late spring and early summer. Mixed layers throughout the region shoaled in summer due to surface heating, while the addition of freshwater from melting sea ice enhanced strati"cation in the Seasonal Ice Zone, creating conditions favorable for phytoplankton growth. For example, silicic acid concentrations decreased from initial values as high as 65 to less than 2 M within approximately 100 km (from 65.7 to 64.83S). Fluorescence values, however, showed less than a two-fold variation over the same distance. The vertical #ux of carbon in the Polar Front area is substantial, and marked variations in the composition of exported material exited over the region. The results provide a means whereby the controls of phytoplankton growth and organic matter #ux and remineralization can be analyzed in great detail. Additional results of the AESOPS project are discussed.

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“…Moreover, none of the Antarctic heterotrophic bacteria with genomes currently sequenced contain the B 12 biosynthetic pathway (Bertrand et al, 2011). In the Ross Sea, the marine cyanobacteria are numerically non-existent based on microscopy and pigment analysis (Caron et al, 2000;DiTullio, 2003;Bertrand et al, 2007), whereas they comprise a significant component of the microbial community in tropical and subtropical environments (Campbell et al, 1994;DiTullio et al, 2003). In addition, the heterotrophic bacterial community is known to be less numerous and exhibit a strong seasonal cycle in the Ross Sea, in contrast to temperate and tropical oceans (Ducklow et al, 2001).…”

Section: Chemical Speciation Of Cobaltmentioning

confidence: 99%

A seasonal study of dissolved cobalt in the Ross Sea, Antarctica: micronutrient behavior, absence of scavenging, and relationships with Zn, Cd, and P

et al. 2010

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Abstract. We report the distribution of cobalt (Co) showing a significant correlation throughout the water column (r 2 = 0.87, 164 samples). A strong seasonal signal for dCo was observed, with most spring samples having concentrations ranging from ∼45-85 pM, whereas summer dCo values were depleted below these levels by biological activity. Surface transect data from the summer cruise revealed concentrations at the low range of this seasonal variability (∼30 pM dCo), with concentrations as low as 20 pM observed in some regions where PO 3− 4 was depleted to ∼0

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Microzooplankton herbivory in the Ross Sea, Antarctica

Cited by 153 publications

References 47 publications

Phytoplankton and iron limitation of photosynthetic efficiency in the Southern Ocean during late summer

Phytoplankton and iron limitation of photosynthetic efficiency in the Southern Ocean during late summer

The US Southern Ocean Joint Global Ocean Flux Study: an introduction to AESOPS

A seasonal study of dissolved cobalt in the Ross Sea, Antarctica: micronutrient behavior, absence of scavenging, and relationships with Zn, Cd, and P

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