Evidence for the grazing hypothesis: Grazing reduces phytoplankton responses of the HNLC ecosystem to iron enrichment in the western subarctic pacific (SEEDS II)

Tsuda, Atsushi; Takeda, Shigenobu; Saito, Hiroaki; Nishioka, Jun; Kudo, Isao; Nojiri, Yukihiro; Suzuki, Koji; Uematsu, Mitsuo; Wells, Mark L.; Tsumune, Daisuke; Yoshimura, Takeshi; Aono, Tatsuo; Aramaki, Takafumi; Cochlan, William P.; Hayakawa, Maki; Imai, Keiri; Isada, Tomoshi; Iwamoto, Yoko; Johnson, William K.; Kameyama, Sohiko; Kato, S.; Kiyosawa, Hiroshi; Kondo, Yoshiko; Levasseur, Maurice; Machida, Ryuji J.; Nagao, Ippei; Nakagawa, Fumiko; Nakanishi, Takahiro; Nakatsuka, Seiji; Narita, Akira; Noiri, Yoshifumi; Obata, Hajime; Ogawa, Hiroshi; Oguma, Kenji; Ono, Tsuneo; Sakuragi, Tomofumi; Sasakawa, Motoki; Sato, Minoru; Shimamoto, Akifumi; Takata, Hyoe; Trick, Charles G.; Watanabe, Yutaka; Wong, C. S.; Yoshie, Naoki

doi:10.1007/s10872-007-0082-x

Cited by 84 publications

(51 citation statements)

References 44 publications

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“…Moreover, an inverse relationship between export efficiency and zooplankton biomass in the Kerguelen Plateau region supports the key role of grazers in the HBLE scenario (Laurenceau-Cornec et al, 2015). Efficient grazer responses to phytoplankton biomass following artificial iron fertilization of HNLC regions also demonstrate increases in net community production that are not translated to an increase in export fluxes (Lam and Bishop, 2007;Tsuda et al, 2007;Martin et al, 2013;Batten and Gower, 2014).…”

Section: Rembauville Et Al: Seasonal Dynamics Of Particulate Orgamentioning

confidence: 64%

Export fluxes in a naturally iron-fertilized area of the Southern Ocean – Part 1: Seasonal dynamics of particulate organic carbon export from a moored sediment trap

et al. 2015

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Abstract.A sediment trap moored in the naturally ironfertilized Kerguelen Plateau in the Southern Ocean provided an annual record of particulate organic carbon and nitrogen fluxes at 289 m. At the trap deployment depth, current speeds were typically low ( ∼ 10 cm s −1 ) and primarily tidaldriven (M2 tidal component). Although advection was weak, the sediment trap may have been subject to hydrodynamical and biological (swimmer feeding on trap funnel) biases. Particulate organic carbon (POC) flux was generally low (< 0.5 mmol m −2 d −1 ), although two episodic export events (< 14 days) of 1.5 mmol m −2 d −1 were recorded. These increases in flux occurred with a 1-month time lag from peaks in surface chlorophyll and together accounted for approximately 40 % of the annual flux budget. The annual POC flux of 98.2 ± 4.4 mmol m −2 yr −1 was low considering the shallow deployment depth but comparable to independent estimates made at similar depths (∼ 300 m) over the plateau, and to deep-ocean (> 2 km) fluxes measured from similarly productive iron-fertilized blooms. Although undertrapping cannot be excluded in shallow moored sediment trap deployment, we hypothesize that grazing pressure, including mesozooplankton and mesopelagic fishes, may be responsible for the low POC flux beneath the base of the winter mixed layer. The importance of plankton community structure in controlling the temporal variability of export fluxes is addressed in a companion paper.

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Section: Rembauville Et Al: Seasonal Dynamics Of Particulate Orgamentioning

confidence: 64%

Export fluxes in a naturally iron-fertilized area of the Southern Ocean – Part 1: Seasonal dynamics of particulate organic carbon export from a moored sediment trap

et al. 2015

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“…Photochemical quan- Tsuda et al (2003), Boyd et al (2004), Wong et al (2006b), Tsuda et al (2007), and Nishioka et al (2009).…”

Section: -1 Summary Of Biological and Geochemical Findings In Seedsmentioning

confidence: 99%

Iron and Phytoplankton Growth in the Subarctic North Pacific

Takeda¹

2011

Aqua-BioSci. Monogr. (ABSM)

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“…The Subarctic Pacific Iron Experiment for Ecosystem Dynamics Study (SEEDS) II project constitutes a notable exception because there was a muted response to Fe addition despite high silicic acid concentrations. This lack of diatom increase was attributed to high grazing pres sure of mesozooplankton (Tsuda et al 2007), al though a complementary explanation is the absence of certain siderophores produced by some bacteria that prevented the uptake of Fe by diatoms (Wells et al 2009).…”

Section: Introductionmentioning

confidence: 99%

Progressive decoupling between phytoplankton growth and microzooplankton grazing during an iron-induced phytoplankton bloom in the Southern Ocean (EIFEX)

Latasa¹,

Henjes²,

Scharek³

et al. 2014

Mar. Ecol. Prog. Ser.

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Dilution experiments were performed to quantify growth and mortality rates of phytoplankton groups (as defined by pigment markers) for 5 wk in an iron-induced phytoplankton bloom during the European Iron Fertilization Experiment (EIFEX) conducted in the Southern Ocean. Rates could be reliably measured for the 2 main groups, diatoms and prymnesiophytes. Mean phytoplankton intrinsic growth rates were around 0.23 d ), leading to an increase in decoupling between phytoplankton growth and microzooplankton grazing. The decrease in grazing was correlated with the decrease in concentrations of small microprotozooplankton (< 60 µm). As a consequence, net growth in the dilution experiments increased from around 0 d −1 up to 0.13 d −1 in the last days of the experiment, 35 d after the initial iron fertilization. This pattern did not reflect the dynamics of net phytoplankton accumulation in the fertilized patch, which increased until Days 24 to 27 and decreased thereafter. The difference between experimental and natural phytoplankton net growth is the biomass that escapes microzooplankton grazing and does not accumulate in the surface mixed layer, i.e. the biomass that went to higher trophic levels plus that exported out of the mixed layer. It increased throughout EIFEX and suggests a shift from a predominantly recycling system towards a more exporting one.

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Evidence for the grazing hypothesis: Grazing reduces phytoplankton responses of the HNLC ecosystem to iron enrichment in the western subarctic pacific (SEEDS II)

Cited by 84 publications

References 44 publications

Export fluxes in a naturally iron-fertilized area of the Southern Ocean – Part 1: Seasonal dynamics of particulate organic carbon export from a moored sediment trap

Export fluxes in a naturally iron-fertilized area of the Southern Ocean – Part 1: Seasonal dynamics of particulate organic carbon export from a moored sediment trap

Iron and Phytoplankton Growth in the Subarctic North Pacific

Progressive decoupling between phytoplankton growth and microzooplankton grazing during an iron-induced phytoplankton bloom in the Southern Ocean (EIFEX)

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