Lateral organic carbon supply to the deep Canada Basin

Hwang, Jeomshik; Eglinton, T. I.; Krishfield, Richard A.; Manganini, Steven J.; Honjo, Susumu

doi:10.1029/2008gl034271

Cited by 47 publications

(65 citation statements)

References 32 publications

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“…These include the possibility of lateral advection of previously deposited sediment material from the nearby shelf or slope (20,22), which is of particular relevance given the location of their trap. The seasonal oscillation in morphotypes probably takes place in all years but cannot always be seen in deep sediment-trap sampling.…”

Section: Resultsmentioning

confidence: 99%

Predominance of heavily calcified coccolithophores at low CaCO ₃ saturation during winter in the Bay of Biscay

Smith

Tyrrell

Charalampopoulou

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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Coccolithophores are an important component of the Earth system, and, as calcifiers, their possible susceptibility to ocean acidification is of major concern. Laboratory studies at enhanced pCO 2 levels have produced divergent results without overall consensus. However, it has been predicted from these studies that, although calcification may not be depressed in all species, acidification will produce "a transition in dominance from more to less heavily calcified coccolithophores" [Ridgwell A, et al., (2009) Biogeosciences 6:2611-2623. A recent observational study [Beaufort L, et al., (2011) Nature 476:80-83] also suggested that coccolithophores are less calcified in more acidic conditions. We present the results of a large observational study of coccolithophore morphology in the Bay of Biscay. Samples were collected once a month for over a year, along a 1,000-km-long transect. Our data clearly show that there is a pronounced seasonality in the morphotypes of Emiliania huxleyi, the most abundant coccolithophore species. Whereas pH and CaCO 3 saturation are lowest in winter, the E. huxleyi population shifts from <10% (summer) to >90% (winter) of the heavily calcified form. However, it is unlikely that the shifts in carbonate chemistry alone caused the morphotype shift. Our finding that the most heavily calcified morphotype dominates when conditions are most acidic is contrary to the earlier predictions and raises further questions about the fate of coccolithophores in a high-CO 2 world.phytoplankton | North Atlantic | climate change C occolithophores contribute between ∼1% and 10% of marine primary production (1), dominate the pelagic calcium carbonate flux (2), and alter ocean albedo (3). Model predictions suggest that, if CO 2 emissions continue unabated, global surface ocean pH will decrease by 0.3-0.5 units by 2100, leading to a halving of the carbonate ion concentration (4). Along with other calcifiers, coccolithophores such as Emiliania huxleyi are considered susceptible to this ocean acidification (OA). This hypothesis is contentious, however, with diverse calcification responses reported for culture experiments. Many experiments on E. huxleyi (the most common coccolithophore) have found depressed calcification at elevated CO 2 concentration and the associated low pH and low CaCO 3 saturation state (Ω) (5-11), whereas others have found elevated calcification (12, 13) or no trend (10). An in-depth discussion on the reasons behind the contrasting results of Riebesell et al. (5) and can be found in refs. 14 and 15. In a recent study, four different strains of E. huxleyi cultured under identical environmental conditions exhibited varying responses to elevated CO 2 (16), as was also found between coccolithophore species (17).Laboratory studies are unrealistic in many respects and, because of their typically short timescales, preclude the possibility of evolutionary adaptation to the imposed change, a key uncertainty in OA research (17-19). It is therefore vital to complement laboratory experiments with observ...

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Section: Resultsmentioning

confidence: 99%

Predominance of heavily calcified coccolithophores at low CaCO ₃ saturation during winter in the Bay of Biscay

Smith

Tyrrell

Charalampopoulou

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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“…Forest et al, 2007;Hwang et al, 2008;Honjo et al, 2010;Smith, 2010;O'Brien et al, 2011O'Brien et al, , 2013Watanabe et al, 2014). The role of horizontal transfer is believed to be particularly important for organic carbon cycling in the deep Canada Basin where primary productivity is low ( $ 5 g C m À 2 yr À 1 ; Lee and Whitledge, 2005) and where vertical POC fluxes derived from autochthonous processes are insignificant (about $ 1 mg C m À 2 d À 1 ; Honjo et al, 2010).…”

Section: The Importance Of Shelf-slope Transport Of Particulate Mattementioning

confidence: 98%

“…The role of horizontal transfer is believed to be particularly important for organic carbon cycling in the deep Canada Basin where primary productivity is low ( $ 5 g C m À 2 yr À 1 ; Lee and Whitledge, 2005) and where vertical POC fluxes derived from autochthonous processes are insignificant (about $ 1 mg C m À 2 d À 1 ; Honjo et al, 2010). In the Canada Basin, the majority of particulate matter is refractory, old (∼1900 years; Hwang et al, 2008) and supplied by the surrounding margins through mesoscale eddies and other physical processes, primarily during the winter months (Forest et al, 2007;O'Brien et al, 2011;. The organic matter injected in the basin apparently supports a microbial food web dominated by low phytoplankton biomass and small cells, active bacterial heterotrophy and recycling -while zooplankton (and fish) production remains poorly developed (Honjo et al, 2010;Shah et al, 2013;Forest et al, 2014 and references therein).…”

Section: The Importance Of Shelf-slope Transport Of Particulate Mattementioning

confidence: 99%

Physical forcings and intense shelf–slope fluxes of particulate matter in the halocline waters of the Canadian Beaufort Sea during winter

Forest

Osborne

Fortier

et al. 2015

Continental Shelf Research

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“…Lateral transport has also been invoked to explain old radiocarbon ages of sinking POC (Hwang et al 2004(Hwang et al , 2008. Because the long-distance transport of margin-derived material is likely to be dominated by fine, suspended material, the increasing flux with depth seems to imply deep aggregation processes that allow the incorporation of margin-derived fine, suspended particles into sinking particles.…”

Section: Other Geochemical Evidence For Particle Dynamicsmentioning

confidence: 99%

Insights into Particle Cycling from Thorium and Particle Data

Lam

Marchal

2015

Annu. Rev. Mar. Sci.

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Marine particles are a main vector by which the biological carbon pump in the ocean transfers carbon from the atmosphere to the deep ocean. Marine particles exist in a continuous spectrum of sizes, but they can be functionally grouped into a small, suspended class (which constitutes most of the total particle mass) and a large, sinking class (which contributes most of the particle flux). These two classes are connected by aggregation and disaggregation processes. The interplay of processes that create, aggregate, and destroy marine particles determines the strength and transfer efficiency of the biological pump. Measurements of radiocarbon, barium, and organic biomarkers on suspended and sinking particles have provided qualitative insights into particle dynamics, and measurements of thorium isotopes have provided quantitative estimates of rates. Here, we review what has been learned so far about particle dynamics in the ocean from chemical 2 measurements on suspended and sinking particles. We then discuss future directions for this approach.

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Lateral organic carbon supply to the deep Canada Basin

Cited by 47 publications

References 32 publications

Predominance of heavily calcified coccolithophores at low CaCO ₃ saturation during winter in the Bay of Biscay

Predominance of heavily calcified coccolithophores at low CaCO ₃ saturation during winter in the Bay of Biscay

Physical forcings and intense shelf–slope fluxes of particulate matter in the halocline waters of the Canadian Beaufort Sea during winter

Insights into Particle Cycling from Thorium and Particle Data

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Lateral organic carbon supply to the deep Canada Basin

Cited by 47 publications

References 32 publications

Predominance of heavily calcified coccolithophores at low CaCO 3 saturation during winter in the Bay of Biscay

Predominance of heavily calcified coccolithophores at low CaCO 3 saturation during winter in the Bay of Biscay

Physical forcings and intense shelf–slope fluxes of particulate matter in the halocline waters of the Canadian Beaufort Sea during winter

Insights into Particle Cycling from Thorium and Particle Data

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Product

Resources

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Predominance of heavily calcified coccolithophores at low CaCO ₃ saturation during winter in the Bay of Biscay

Predominance of heavily calcified coccolithophores at low CaCO ₃ saturation during winter in the Bay of Biscay