An approach for particle sinking velocity measurements in the 3–400 μm size range and considerations on the effect of temperature on sinking rates

Bach, Lennart T.; Riebesell, Ulf; Sett, Scarlett; Febiri, Sarah; Rzepka, Paul; Schulz, Kai G.

doi:10.1007/s00227-012-1945-2

Cited by 124 publications

(135 citation statements)

References 41 publications

(64 reference statements)

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“…Moreover, further investigations are needed to better understand the differential effects of an increase in bioavailable P stock as a result of the atmospheric deposition on phytoplankton growth in the coastal seas and open oceans. In terms of autotrophs, the stimulation of large-sized phytoplankton growth due to the input of AM dust might enhance the carbon storage in the deep ocean, as the sinking rates of large-sized cells in the water column are higher than the pico-sized ones (Bach et al, 2012). On the other hand, the increasing anthropogenic activities in recent years can also increase the contents of heavy metal in the dust, which may inhibit phytoplankton growth (Miao et al, 2005;Paytan et al, 2009).…”

Section: Resultsmentioning

confidence: 99%

Phytoplankton growth response to Asian dust addition in the northwest Pacific Ocean versus the Yellow Sea

et al. 2018

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Abstract. In this study, five on-board microcosm experiments were performed in the subtropical gyre, the Kuroshio Extension region of the northwest Pacific Ocean (NWPO), and the Yellow Sea (YS) in order to investigate phytoplankton growth following the addition of artificially modified mineral dust (AM dust) and various nutrients (nitrogen (N), phosphorus (P), iron (Fe), N + P, and N + P + Fe). The two experiments carried out with AM-dust addition in the subtropical gyre showed a maximum chlorophyll a (Chl a) concentration increase of 1.7-and 2.8-fold, while the cell abundance of large-sized phytoplankton (> 5 µm) showed a 1.8-and 3.9-fold increase, respectively, relative to the controls. However, in the Kuroshio Extension region and the YS, the increases in maximum Chl a and cell abundance of largesized phytoplankton following AM-dust addition were at most 1.3-fold and 1.7-fold larger than those in the controls, respectively. A net conversion efficiency index (NCEI) newly proposed in this study, size-fractionated Chl a, and the abundance of large-sized phytoplankton were analysed to determine which nutrients contribute to supporting phytoplankton growth. Our results demonstrate that a combination of nutrients, N-P or N + P + Fe, is responsible for phytoplankton growth in the subtropical gyre following AM-dust addition. Single nutrient addition, i.e., N in the Kuroshio Extension region and P or N in the YS, controls the phytoplankton growth following AM-dust addition. In the AM-dust-addition experiments, in which the increased N-P or P was identified to determine phytoplankton growth, the dissolved inorganic P from AM dust (8.6 nmol L −1 ) was much lower than the theoretically estimated minimum P demand (∼ 20 nmol L −1 ) for phytoplankton growth. These observations suggest that additional supply augments the bioavailable P stock in incubated seawater with AM-dust addition, most likely due to an enhanced solubility of P from AM dust or the remineralization of the dissolved organic P.

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Section: Resultsmentioning

confidence: 99%

Phytoplankton growth response to Asian dust addition in the northwest Pacific Ocean versus the Yellow Sea

et al. 2018

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“…This would allow disentanglement of proxy data from microorganisms with different traits and a better spatial interpretation of the signal around the location of the sediment core site. Coccolithophores, for example, are also paleoclimatological proxy carriers of primary importance, with life traits and settling dynamics that differ notably from planktic foraminifera 25 . With an approach similar to ours, coccolithophoric footprints could be calculated and compared with the foraminiferal ones, potentially vastly increasing the amount of information that can be obtained from a single sediment core.…”

Section: Discussionmentioning

confidence: 99%

Ocean currents generate large footprints in marine palaeoclimate proxies

et al. 2015

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Fossils of marine microorganisms such as planktic foraminifera are among the cornerstones of palaeoclimatological studies. It is often assumed that the proxies derived from their shells represent ocean conditions above the location where they were deposited. Planktic foraminifera, however, are carried by ocean currents and, depending on the life traits of the species, potentially incorporate distant ocean conditions. Here we use high-resolution ocean models to assess the footprint of planktic foraminifera and validate our method with proxy analyses from two locations. Results show that foraminifera, and thus recorded palaeoclimatic conditions, may originate from areas up to several thousands of kilometres away, reflecting an ocean state significantly different from the core site. In the eastern equatorial regions and the western boundary current extensions, the offset may reach 1.5°C for species living for a month and 3.0°C for longer-living species. Oceanic transport hence appears to be a crucial aspect in the interpretation of proxy signals.

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“…Although sinking velocities < 1 m d -1 have been reported for cell material from individual cultures of certain phytoplankton species (Bach et al, 2012) and for certain lithogenic particles of Aeolian origin (Ohnemus and Lam, 2014), a median W avg of 50 m d -1 (interquartile range, 11.5-100 m d -1 ; mean, 63.8 m d -1 ) emerged from a data set of observations we assembled from the literature for the temperate North Atlantic Ocean at depths < 1000 m (Table C. (Berelson, 2002;McDonnell et al, 2015;Stemmann et al, 2004a). In instances where a bimodal distribution of particle sinking velocities has been observed in the North Atlantic, a slow-sinking particle size fraction can be complemented by a fast-sinking fraction with an average sinking velocity of nearly 200 m d -1 .…”

Section: Minimum Constraints On Average Particle Sinking Velocitymentioning

confidence: 96%

The remineralization of marine organic matter by diverse biological and abiotic processes

Collins¹

2017

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While aerobic respiration is typically invoked as the dominant mass-balance sink for organic matter in the upper ocean, many other biological and abiotic processes can degrade particulate and dissolved substrates on globally significant scales. The relative strengths of these other remineralization processes -including mechanical mechanisms such as dissolution and disaggregation of sinking particles, and abiotic processes such as photooxidation -remain poorly constrained. In this thesis, I examine the biogeochemical significance of various alternative pathways of organic matter remineralization using a combination of field experiments, modeling approaches, geochemical analyses, and a new, high-throughput lipidomics method for identification of lipid biomarkers. I first assess the relative importance of particleattached microbial respiration compared to other processes that can degrade sinking marine particles. A hybrid methodological approach -comparison of substrate-specific respiration rates from across the North Atlantic basin with Monte Carlo-style sensitivity analyses of a simple mechanistic model -suggested sinking particle material was transferred to the water column by various biological and mechanical processes nearly 3.5 times as fast as it was directly respired, questioning the conventional assumption that direct respiration dominates remineralization. I next present and demonstrate a new lipidomics method and open-source software package for discovery and identification of molecular biomarkers for organic matter degradation in large, high-mass-accuracy HPLC-ESI-MS datasets. I use the software to unambiguously identify more than 1,100 unique lipids, oxidized lipids, and oxylipins in data from cultures of the marine diatom Phaeodactylum tricornutum that were subjected to oxidative stress. Finally, I present the results of photooxidation experiments conducted with liposomes -nonliving aggregations of lipids -in natural waters of the Southern Ocean. A broadband polychromatic apparent quantum yield (AQY) is applied to estimate rates of lipid photooxidation in surface waters of the West Antarctic Peninsula, which receive seasonally elevated doses of ultraviolet radiation as a consequence of anthropogenic ozone depletion in the stratosphere. The mean daily rate of lipid photooxidation (50 ± 11 pmol IP-DAG L −1 d −1 , equivalent to 31 ± 7 g C m −3 d −1 ) represented between 2 and 8 % of the total bacterial production observed in surface waters immediately following the retreat of the sea ice. AcknowledgmentsModern science is a highly collaborative enterprise. And yet -at times -it can be incredibly isolating. A great number of people have nurtured, challenged, and supported me scientifically and emotionally over the past five and a half years as I have operated at fits and starts in each of these modes of scientific inquiry. While I've thanked many of these individuals in these Acknowledgments and in the acknowledgments sections of my separate thesis chapters, I am sure I've committed the sin of omi...

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An approach for particle sinking velocity measurements in the 3–400 μm size range and considerations on the effect of temperature on sinking rates

Cited by 124 publications

References 41 publications

Phytoplankton growth response to Asian dust addition in the northwest Pacific Ocean versus the Yellow Sea

Phytoplankton growth response to Asian dust addition in the northwest Pacific Ocean versus the Yellow Sea

Ocean currents generate large footprints in marine palaeoclimate proxies

The remineralization of marine organic matter by diverse biological and abiotic processes

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