Drivers of particle sinking velocities in the Peruvian upwelling system
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Published:2023-07-05
Issue:13
Volume:20
Page:2595-2612
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ISSN:1726-4189
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Container-title:Biogeosciences
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language:en
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Short-container-title:Biogeosciences
Author:
Baumann MoritzORCID, Paul Allanah JoyORCID, Taucher Jan, Bach Lennart ThomasORCID, Goldenberg Silvan, Stange Paul, Minutolo FabrizioORCID, Riebesell UlfORCID
Abstract
Abstract. As one of Earth's most productive marine ecosystems, the
Peruvian upwelling system transports large amounts of biogenic matter from
the surface to the deep ocean. Whilst particle sinking velocity is a key
factor controlling the biological pump, thereby affecting carbon
sequestration and O2-depletion, it has not yet been measured in this
system. During a 50 d mesocosm experiment in the surface waters off the
coast of Peru, we assessed particle sinking velocities and their
biogeochemical and physical drivers. We further characterized the general
properties of exported particles under different phytoplankton communities
and nutritional states. Average sinking velocities varied between size
classes and ranged from 12.8 ± 0.7 m d−1 (particles 40–100 µm) to 19.4 ± 0.7 m d−1 (particles 100–250 µm)
and 34.2 ± 1.5 m d−1 (particles 250–1000 µm) (± 95 % CI). Despite a distinct plankton succession from diatoms to
dinoflagellates with concomitant 5-fold drop in opal ballasting, substantial
changes in sinking velocity were not observed. This illustrates the
complexity of counteracting factors driving the settling behaviour of marine
particles. In contrast, we found higher sinking velocities with increasing
particle size and roundness and decreasing porosity. Size had by far the
strongest influence among these physical particle properties, despite a high
amount of unexplained variability. Our study provides a detailed analysis of
the drivers of particle sinking velocity in the Peruvian upwelling system,
which allows modellers to optimize local particle flux parameterization. This
will help to better project oxygen concentrations and carbon sequestration
in a region that is subject to substantial climate-driven changes.
Funder
Deutsche Forschungsgemeinschaft Horizon 2020
Publisher
Copernicus GmbH
Subject
Earth-Surface Processes,Ecology, Evolution, Behavior and Systematics
Reference55 articles.
1. Alldredge, A. L. and Crocker, K. M.: Why do sinking mucilage aggregates
accumulate in the water column?, Sci. Total Environ., 165,
15–22, https://doi.org/10.1016/0048-9697(95)04539-D, 1995. 2. Alldredge, A. L. and Gotschalk, C.: In situ settling behavior of marine
snow, Limnol. Oceanogr., 33, 339–351,
https://doi.org/10.4319/lo.1988.33.3.0339, 1988. 3. Armstrong, R. A., Peterson, M. L., Lee, C., and Wakeham, S. G.: Settling
velocity spectra and the ballast ratio hypothesis, Deep-Sea Res. Pt.
II, 56, 1470–1478,
https://doi.org/10.1016/j.dsr2.2008.11.032, 2009. 4. Ayón Dejo, P., Pinedo Arteaga, E. L., Schukat, A., Taucher, J., Kiko,
R., Hauss, H., Dorschner, S., Hagen, W., Segura-Noguera, M., and Lischka,
S.: Zooplankton community succession and trophic links during a mesocosm
experiment in the coastal upwelling off Callao Bay (Peru), Biogeosciences,
20, 945–969, https://doi.org/10.5194/bg-20-945-2023, 2023. 5. Bach, L. T., Riebesell, U., Sett, S., Febiri, S., Rzepka, P., and Schulz, K.
G.: An approach for particle sinking velocity measurements in the 3–400 µm size range and considerations on the effect of temperature on
sinking rates, Mar. Biol., 159, 1853–1864,
https://doi.org/10.1007/s00227-012-1945-2, 2012.
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