Low microzooplankton grazing rates in the Arctic Ocean during a Phaeocystis pouchetii bloom (Summer 2007): fact or artifact of the dilution technique?

Calbet, Albert; Saiz, Enric; Almeda, Rodrigo; Movilla, Juan Ignacio; Alcaraz, Miquel

doi:10.1093/plankt/fbq142

Cited by 46 publications

(51 citation statements)

References 54 publications

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“…1). These trends in BCF values are due in part to changes in phytoplankton community and abundance, which was dominated by colonies of Phaeocystis pouchetti, and followed by diatoms, the abundance of which showed a dependence with temperature [26][27] . Indeed, PCB concentrations in phytoplankton were significantly correlated with biomass abundance (C P = 2.99×Phaeocystis Biomass + 43.5, r 2 = 0.76, P < 0.01), and the variability in seawater and plankton-phase concentrations was higher in the ice-margin zone.…”

Section: Discussionmentioning

confidence: 99%

The oceanic biological pump modulates the atmospheric transport of persistent organic pollutants to the Arctic

et al. 2012

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semivolatile persistent organic pollutants have the potential to reach remote environments, such as the Arctic ocean, through atmospheric transport and deposition. Here we show that this transport of polychlorinated biphenyls to the Arctic ocean is strongly retarded by the oceanic biological pump. A simultaneous sampling of atmospheric, seawater and plankton samples was performed in July 2007 in the Greenland Current and Atlantic sector of the Arctic ocean. The atmospheric concentrations declined during atmospheric transport over the Greenland Current with estimated half-lives of 1-4 days. These short half-lives can be explained by the high airto-water net diffusive flux, which is similar in magnitude to the estimated settling fluxes in the water column. Therefore, the decrease of atmospheric concentrations is due to sequestration of atmospheric polychlorinated biphenyls by enhanced air-water diffusive fluxes driven by phytoplankton uptake and organic carbon settling fluxes (biological pump).

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Section: Discussionmentioning

confidence: 99%

The oceanic biological pump modulates the atmospheric transport of persistent organic pollutants to the Arctic

et al. 2012

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“…The relative contribution of phytoplankton to zooplankton food was estimated as the quotient between >5 µm chlorophyll carbon and total microplankton carbon (C CHL /ZF). A detailed description of the method can be found in Calbet et al (2011). The taxonomic composition of zooplankton in the experiments was estimated using automatic image analysis and identification software as described below.…”

Section: Variability Sources For Zooplankton Metabolism Other Than Tementioning

confidence: 99%

Effects of temperature on the metabolic stoichiometry of Arctic zooplankton

et al. 2013

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We assessed the relationship between zooplankton metabolism (respiration and inorganic N and P excretion) and "in situ" temperature through a grid of stations representing a range of natural temperature variation during the ATOS-Arctic cruise (July 2007). The objective was to explore not only the direct effects of temperature on zooplankton carbon respiratory losses (hereafter CR) and NH4-N and PO4-P excretion rates (hereafter NE and PE, respectively), but also to investigate whether these metabolic pathways responded similarly to temperature, and so how temperature could affect the stoichiometry of the metabolic products. Metabolic rates, normalised to per unit of zooplankton carbon biomass, increased with increasing temperature following the Arrhenius equation. However, the activation energy differed for the various metabolic processes considered. Respiration, CR, was the metabolic activity least affected by temperature, followed by NE and PE, and as a consequence the values of the CR : NE, CR : PE and NE : PE atomic quotients were inversely related to temperature. The effects of temperature on the stoichiometry of the excreted N and P products would contribute to modifying the nutrient pool available for phytoplankton and induce qualitative and quantitative shifts in the size, community structure and chemical composition of primary producers that could possibly translate to the whole Arctic marine food web

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“…It is very likely that this proportion is higher because experiments with nonsignificant slopes often are not published. Moreover, some researchers choose not to report the values of nonsignificant slopes (i.e., grazing rates; e.g., Kamiyama 1994;Caron et al 2000;Calbet et al 2010). I argue that the rejection of results from dilution experiments because they do not conform to the usual null hypothesis leads to an overestimation of the grazing rates in published databases.…”

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confidence: 99%

“…From this exercise, it is clear that the rejection of experiments with grazing rates not statistically different from zero, based on a model where H 0 : b 5 0, will result in overestimates of grazing and growth rates in the published literature. On the other hand, some investigators (Strom et al 2001;Calbet and Landry 2004;Sherr et al 2009) substituted slightly negative grazing rates by a value of zero because negative rates are theoretically impossible. In the database of Table 1, this change would have resulted in an overesti- Fig.…”

mentioning

confidence: 99%

“…The close coupling between growth and grazing generally implies that experiments with low grazing and nonsignificant slopes also represent low growth rates (Calbet and Landry 2004). Thus, a further implication of discarding experiments with nonsignificant regressions is to eliminate ecological situations of low growth and grazing and results in an overestimation of phytoplankton growth rates (turnover) in our global database.…”

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confidence: 99%

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Comment: A potential bias in the databases of phytoplankton growth and microzooplankton grazing rates because of the improper formulation of the null hypothesis in dilution experiments

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2014

Limnology & Oceanography

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Low microzooplankton grazing rates in the Arctic Ocean during a Phaeocystis pouchetii bloom (Summer 2007): fact or artifact of the dilution technique?

Cited by 46 publications

References 54 publications

The oceanic biological pump modulates the atmospheric transport of persistent organic pollutants to the Arctic

The oceanic biological pump modulates the atmospheric transport of persistent organic pollutants to the Arctic

Effects of temperature on the metabolic stoichiometry of Arctic zooplankton

Comment: A potential bias in the databases of phytoplankton growth and microzooplankton grazing rates because of the improper formulation of the null hypothesis in dilution experiments

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