Mesozooplankton distribution and grazing during the productive season in the Northwest Antarctic Peninsula (FRUELA cruises)

Cabal, J.; Álvarez-Marqués, Florentina; Acuña, José Luis; Quevedo, Mario; González-Quirós, R.; Huskin, I.; Fernández, Diego; Valle, Carlos Rodriguez del; Anadón, Ricardo

doi:10.1016/s0967-0645(01)00128-x

Cited by 35 publications

(26 citation statements)

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“…Similarly, the 500 -1000 mm size fraction also shows low biomass (range of average values 8.6-52.5 mg dry weight m À2 ). The >1000mm size fraction is the best represented in terms of biomass in these waters [see Robins et al, 1995] and average values were in the range of 30.5 -395.0 mg dry weight m À2 [Hernández-León et al, 1999Cabal et al, 2002]. Our estimation of biomass agreed with the ranges obtained for the smaller size fractions, while for the larger we found a higher value (Table 2).…”

Section: Discussionsupporting

confidence: 83%

“…The results of biomass obtained in the area we sampled near the Antarctic Peninsula are comparable with other estimates of biomass in the same area. In the Bransfield Strait, values of biomass of the 200–500 μm size fraction in the upper 200 m layer is a rather small percentage of total biomass [ Robins et al , 1995] and average values ranged from 32.3 to 162.5 mg dry weight m −2 [ Hernández‐León et al , 1999, 2000; Cabal et al , 2002]. Similarly, the 500–1000 μm size fraction also shows low biomass (range of average values 8.6–52.5 mg dry weight m −2 ).…”

Section: Discussionmentioning

confidence: 99%

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Zooplankton biomass estimated from digitalized images in Antarctic waters: A calibration exercise

Hernández‐León

Montero

2006

J. Geophys. Res.

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The direct measurement of zooplankton biomass following the different analytical procedures normally requires the destruction of the samples. The use of conversion factors to estimate biomass from nondestructive methods is still a challenge. The widespread use of image analyzers and optical counters in biological oceanography provides a useful tool to measure the abundance and size spectrum of zooplanktonic organisms in real or quasi‐real time. Both methodologies measure the equivalent spherical diameter and/or the body area of organisms. In order to estimate biomass from the highly valuable information generated by the size spectrum of the sample, we measured the relationship between individual body area and individual biomass of the most common species and groups of zooplankton in Antarctic waters. The slope of the regression for each different species and groups of taxa was not significantly different from that obtained by pooling all taxa, thus providing a general relationship for the entire size spectrum of zooplankton. The biomass estimated from the body area spectrum of samples obtained around the Antarctic Peninsula agreed with other measurements of biomass in the region. The proposed conversion factor could provide for rapid estimates of biomass of net‐collected zooplankton from imaging devices or optical plankton counters.

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Section: Discussionsupporting

confidence: 83%

Section: Discussionmentioning

confidence: 99%

Zooplankton biomass estimated from digitalized images in Antarctic waters: A calibration exercise

Hernández‐León

Montero

2006

J. Geophys. Res.

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“…L. helicina is typically abundant throughout the Southern Ocean, sometimes displacing krill as the dominant zooplankton (17). In McMurdo Sound, L. helicina may constitute more than 20% of the zooplankton biomass and reach concentrations exceeding 300 individuals per cubic meter along the ice edge (18,19).…”

mentioning

confidence: 99%

Cascading Trophic Impacts of Reduced Biomass in the Ross Sea, Antarctica: Just the Tip of the Iceberg?

Seibel

Dierssen

2003

The Biological Bulletin

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A significant reduction in phytoplankton biomass in the Ross Sea was reported in the austral summer of 2000-2001, a possible consequence of a disruption in sea-ice retreat due to the presence of an immense iceberg, B15 (1) (Fig. 1). Our observations in McMurdo Sound suggest temporally and trophically cascading impacts of that depression in productivity. Reduced phytoplankton stocks clearly affected the pteropod Limacina helicina (Phipps, 1774) (Gastropoda: Mollusca), an abundant primary consumer in the region (2, 3), as indicated by depressed metabolic rates in 2000-2001. The following season, for the first time on record, L. helicina was absent from McMurdo Sound. Many important predators, including whales and fishes, rely heavily on L. helicina for food (3, 4). However, most obviously impacted by its absence was Clione antarctica (Smith, 1902), an abundant pteropod mollusc (Gastropoda) that feeds exclusively on L. helicina (5). Metabolic rates of C. antarctica were depressed by 50% in 2001-2002. Both L. helicina and C. antarctica are important components of polar ecosystems and may be good indicators of overall ecosystem "health" in McMurdo Sound and perhaps in the Ross Sea. In this last austral summer, 2002-2003, sea-ice extent was much higher and phytoplankton stocks were dramatically lower than any reported previously, effects possibly associated with El Niño conditions, and we hypothesize that pteropods and their consumers may be further impacted. In the Southern Ocean, phytoplankton production is linked strongly to the seasonal oscillations in the extent of the sea ice (6, 7) and survival of higher trophic levels is

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“…Southern Ocean Pteropods comprise up to one-quarter of total zooplankton biomass in the Ross Sea (13), Weddell Sea (14), and East Antarctica (15), can sometimes displace krill as the dominant zooplankton (16), and dominate carbonate export fluxes south of the Antarctic Polar Front (17), and even organic carbon export (18). Pteropods in Southern Ocean sediment traps show partial dissolution and ''frosted'' appearance of shells just below the aragonite saturation horizon (17,19), indicating vulnerability to low carbonate ion concentrations.…”

Section: Resultsmentioning

confidence: 99%

Southern ocean acidification: A tipping point at 450ppm atmospheric CO2

McNeil

Matear

2009

IOP Conf. Ser.: Earth Environ. Sci.

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Southern Ocean acidification via anthropogenic CO2 uptake is expected to be detrimental to multiple calcifying plankton species by lowering the concentration of carbonate ion (CO 3 2؊ ) to levels where calcium carbonate (both aragonite and calcite) shells begin to dissolve. Natural seasonal variations in carbonate ion concentrations could either hasten or dampen the future onset of this undersaturation of calcium carbonate. We present a large-scale Southern Ocean observational analysis that examines the seasonal magnitude and variability of CO 3 2؊ and pH. Our analysis shows an intense wintertime minimum in CO 3 2؊ south of the Antarctic Polar Front and when combined with anthropogenic CO2 uptake is likely to induce aragonite undersaturation when atmospheric CO2 levels reach Ϸ450 ppm. Under the IPCC IS92a scenario, Southern Ocean wintertime aragonite undersaturation is projected to occur by the year 2030 and no later than 2038. Some prominent calcifying plankton, in particular the Pteropod species Limacina helicina, have important veliger larval development during winter and will have to experience detrimental carbonate conditions much earlier than previously thought, with possible deleterious flow-on impacts for the wider Southern Ocean marine ecosystem. Our results highlight the critical importance of understanding seasonal carbon dynamics within all calcifying marine ecosystems such as continental shelves and coral reefs, because natural variability may potentially hasten the onset of future ocean acidification. ) substantially since preindustrial times (1-3). These changes, particularly with respect to carbonate ion, strongly vary between ocean basins. Over the 21st century, the carbonate ion levels over most of the surface ocean are expected to remain supersaturated with respect to aragonite (2, 3), the more soluble form of calcium carbonate. Despite this, studies have demonstrated that calcifying organisms depend on variations in aragonite saturation state (3-5). Aragonite saturation in seawater allows marine organisms to adequately secrete and accumulate this carbonate mineral during growth and development. The Southern Ocean (south of 60°S), however, is predicted to begin to experience aragonite undersaturation by the year 2050 if assuming surface ocean CO 2 equilibrium with the atmosphere, while most ocean models suggest that mean surface conditions throughout the Southern Ocean will become undersaturated by the year 2100 (3). Aragonite undersaturation both enhances the dissolution of aragonite and reduces formation of aragonite shells of marine organisms (4-7), making the prediction of aragonite undersaturation by the end of this century of particular concern to the Southern Ocean marine ecosystem. Systematic natural seasonal variations of pH and CO 3 2Ϫ can either amplify or depress the onset of future ocean acidification and aragonite undersaturation. Although seasonal variability has been suggested to hasten the onset of aragonite undersaturation (3), observational evidence in the Southern Ocean has...

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Mesozooplankton distribution and grazing during the productive season in the Northwest Antarctic Peninsula (FRUELA cruises)

Cited by 35 publications

References 29 publications

Zooplankton biomass estimated from digitalized images in Antarctic waters: A calibration exercise

Zooplankton biomass estimated from digitalized images in Antarctic waters: A calibration exercise

Cascading Trophic Impacts of Reduced Biomass in the Ross Sea, Antarctica: Just the Tip of the Iceberg?

Southern ocean acidification: A tipping point at 450ppm atmospheric CO2

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