Time-dependency of microzooplankton grazing and phytoplankton growth in the subarctic Pacific

Landry, Michael R.; Monger, Bruce C.; Selph, Karen E.

doi:10.1016/0079-6611(93)90014-5

Cited by 89 publications

(50 citation statements)

References 32 publications

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“…These results are consistent with traditional food web models (Michaels and Silver, 1988;Legendre and Le Fèvre, 1995) that suggest nano-and picoplankton are underrepresented in particle flux relative to their contribution to phytoplankton biomass; they also lend support to the conclusions of Choi et al (2014). However, the methods employed in this study do not quantitatively account for export via zooplankton fecal pellets, which could be significant for small phytoplankton as they are controlled by grazing in this region (Landry et al, 1993;Harrison et al, 1999;Rivkin et al, 1999;Thibault et al, 1999). Furthermore, the determination of pigment loss rates also required a comparison between smalland large-volume samples, and the inherent differences of these sampling techniques likely led to an overestimation of the microplankton contribution to algal aggregate export.…”

Section: Discussionsupporting

confidence: 79%

“…Indirect export (via grazing) is thought to be an important pathway for picoplankton export in the HNLC equatorial Pacific (Richardson et al, 2004;Stukel and Landry, 2010). Given that grazing has been shown to control the biomass of small phytoplankton in the northeast Pacific (Landry et al, 1993;Harrison et al, 1999;Rivkin et al, 1999), indirect export may also be a significant pathway for small cell export in this region. Because this pathway is not accounted for by the methodology employed in this study, the results presented here may underestimate the export of small phytoplankton, which may be less likely to sink directly.…”

Section: Discussionmentioning

confidence: 99%

“…Previous attempts to resolve the apparent paradox of low phytoplankton biomass and high nitrate concentrations at OSP concluded that a bottom-up control related to iron limitation is most important for large phytoplankton (Muggli et al, 1996;Harrison, 2006;Marchetti et al, 2006), while microzooplankton grazing exerts a strong topdown control on pico-and nanoplankton (Landry et al, 1993;Harrison et al, 1999;Rivkin et al, 1999). Primary production at the stations proximal to the coast on Line P (P4 and P12) is not iron-limited, and diatom blooms are typically observed in spring and late summer (Boyd and Harrison, 1999;Thibault et al, 1999).…”

Section: Introductionmentioning

confidence: 99%

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Estimates of micro-, nano-, and picoplankton contributions to particle export in the northeast Pacific

et al. 2015

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Abstract. The contributions of micro-, nano-, and picoplankton to particle export were estimated from measurements of size-fractionated particulate 234 Th, organic carbon, and phytoplankton indicator pigments obtained during five cruises between 2010 and 2012 along Line P in the subarctic northeast Pacific Ocean. Sinking fluxes of particulate organic carbon (POC) and indicator pigments were calculated from 234 Th-238 U disequilibria and, during two cruises, measured by a sediment trap at Ocean Station Papa. POC fluxes at 100 m ranged from 0.65 to 7.95 mmol m −2 d −1 , similar in magnitude to previous results at Line P. Microplankton pigments dominate indicator pigment fluxes (averaging 69 ± 19 % of total pigment flux), while nanoplankton pigments comprised the majority of pigment standing stocks (averaging 64 ± 23 % of total pigment standing stocks). Indicator pigment loss rates (the ratio of pigment export flux to pigment standing stocks) point to preferential export of larger microplankton relative to smaller nano-and picoplankton. However, indicator pigments do not quantitatively trace particle export resulting from zooplankton grazing, which may be an important pathway for the export of small phytoplankton. These results have important implications for understanding the magnitude and mechanisms controlling the biological pump at Line P in particular, and more generally in oligotrophic gyres and high-nutrient, low-chlorophyll (HNLC) regions where small phytoplankton represent a major component of the autotrophic community.

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Section: Discussionsupporting

confidence: 79%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Estimates of micro-, nano-, and picoplankton contributions to particle export in the northeast Pacific

et al. 2015

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“…The present estimates of mesozooplankton grazing (16 to 44 % of phytoplankton production, Table 5) are consistent with the prevailing paradigm that smaller consumers dominate grazing processes in the oceans (Capriulo et al 1991, Lessard 1991, Landry et al 1993. The magnitudes of these grazing:production ratios place the Santa Monica Basin intermediate between open ocean and oligotrophic regions, where mesozooplankton directly utilize 20 % or less of phytoplankton production (e.g.…”

Section: Grazing-flux Relationshipssupporting

confidence: 72%

Mesozooplankton grazing in the Southern California Bight. II. Grazing impact and particulate flux

Landry¹,

Lorenzen²,

Peterson³

1994

Mar. Ecol. Prog. Ser.

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Mesozooplankton grazing on phytoplankton, as inferred from gut pigment contents and gut evacuation rates, was studied in relation to primary production and particulate export flux on 6 cruises in the Santa Monica Basin, California, USA. Gut evacuation rates did not vary significantly among different taxa or size classes examined and were consistent with extrapolations of published temperature relationships. Shipboard incubations with cultured phytoplankton and net-collected zooplankton indicated a seasonal difference in the extent to which gut passage converts chlorophyll to non-fluorescent by-products. In autumn experiments, only about 5 % of ingested chlorophyll could not be recovered as phaeopigment. In winter-spring experiments, approximately 70% of ingested chlorophyll (chl) was destroyed. In contrast, other indices of pigment destruction, the ingestion rates of a dominant copepod species and the ratio of water-column phaeopigment:silica fluxes, did not reveal a significant gut passage effect during winter-spring cruises. Mesozooplankton community grazing impact varied from 1.7 to 7.3 mg chl m-' d-l, with higher grazing during the winter-spring period (mean = 5.8 mg chl m-2 d-l) as compared to the autumn (mean = 2.3 mg chl m-2 d-l). On average, mesozooplankton grazing accounted for a loss of 11.7% of chlorophyll standing stock d-' with a 6 cruise range of 6 to 18% d-' Mesozooplankton grazing on phytoplankton accounted for 29 to 4 4 % (mean = 39%) of measured primary production for the winter-spring cruises, but only 16 to 24% (mean = 19%) of production in the autumn. From measured phaeopigment fluxes into sediment traps below the euphotic zone, only 27.5 % (range 23 to 32%) of this grazing on phytoplankton could be accounted for as export flux. Thus, in terms of contribution to particulate flux or remineralization, most mesozooplankton grazing in the Santa Monica Basin was functionally equivalent to that of microzooplankton. Direct grazing on phytoplankton contributed 15 to 38% of carbon flux into sediment traps during winter-spring and 8 to 13 % during autumn. Nonetheless, if feeding on nonpigmented prey is considered from the available information on carbon:phaeopigment ratios of fresh fecal pellets, over 70 % of the carbon flux to traps could have a mesozooplankton grazing origin.

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“…A dilution approach initially introduced by LANDRY and HASSET (1982) and refined by LANDRY et al (1995) has been routinely used as a field technique to quantify grazing of phytoplankton by micro-zooplankton and to estimate phytoplankton growth rates (CAMPBELL and CARPENTER, 1986;WEISSE and SCHEFFEL-MOSER, 1990;LANDRY et al, 1993;CALBET and LANDRY, 2004). We used a modification of this dilution technique to assess the virusinduced mortality of heterotrophic bacteria in Lake Geneva, which was successfully tested on Lake Bourget the year before (JACQUET et al, 2005).…”

Section: Experimental Set-up To Estimate the Impact Of Viruses And Flmentioning

confidence: 99%

Assessing the microbial community dynamics and the role of bacteriophages in bacterial mortality in Lake Geneva

Duhamel¹,

Domaizon²,

Personnic³

et al. 2006

rseau

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SummaryThe aims of this work were to study, for the first time, the succession of microbial communities (from viruses to ciliates) in the largest occidental European lake (Lake Geneva) and to perform two one-weekin situexperiments in March-April (Exp1) and May (Exp2) 2004 in order to assess both small flagellate protozoan and virus-induced mortality of heterotrophic bacteria. Both nanoflagellates and viruses could be responsible for 31 to 42% of the total daily mortality of heterotrophic bacteria. In May (Exp2), viruses could explain up to 10% of the bacterial mortality whereas flagellates were responsible for 32% of the bacterioplankton removal. These results provide new evidence for the critical role played by viruses in the functioning of the microbial food webs and highlight the importance of further considering this biological compartment for a better understanding of the plankton ecology of Lake Geneva.

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Time-dependency of microzooplankton grazing and phytoplankton growth in the subarctic Pacific

Cited by 89 publications

References 32 publications

Estimates of micro-, nano-, and picoplankton contributions to particle export in the northeast Pacific

Estimates of micro-, nano-, and picoplankton contributions to particle export in the northeast Pacific

Mesozooplankton grazing in the Southern California Bight. II. Grazing impact and particulate flux

Assessing the microbial community dynamics and the role of bacteriophages in bacterial mortality in Lake Geneva

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