Growth and grazing mortality rates of Prochlorococcus, Synechococcus and eukaryotic picophytoplankton in a bay of the Uwa Sea, Japan

Hirose, Miho; Katano, Toshiya; Nakano, Susumu

doi:10.1093/plankt/fbm101

Cited by 28 publications

(15 citation statements)

References 60 publications

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“…Landry et al (1995) The growth and grazing rates of pico-phytoplankton estimated in the present study fall into the middle range of those rates of the main pico-phytoplankton groups (Prochlorococcus, Synechococcus and eukaryotic pico-phytoplankton) reported in previous studies (reviewed data in Table II in Hirose et al, 2008). Based on cell cycle analysis, Yang and Jiao (2002) reported the in situ Prochlorococcus growth rate of 0.54 d −1 at the chlorophyll maximum layer in the SSCS in May.…”

Section: Phytoplankton Growth and Microzooplankton Grazing Rates In Lsupporting

confidence: 56%

Seasonal and size-dependent variations in the phytoplankton growth and microzooplankton grazing in the southern South China Sea under the influence of the East Asian monsoon

et al. 2015

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Abstract.To examine seasonal and size-dependent variations in the phytoplankton growth and microzooplankton grazing in oligotrophic tropical waters under the influence of seasonal reversing monsoon, dilution experiments were conducted during the summer of 2009 (21 May to 9 June) and winter 2010 (9 to 18 November) in the southern South China Sea (SSCS). The results showed that environmental variables, phytoplankton biomass, phytoplankton growth rate (µ), microzooplankton grazing rate (m), and correlationship (coupling) between the µ and m, rather than the microzooplankton grazing impact on phytoplankton (m/µ) significantly varied between the two seasons. Higher relative preference index (RPI) for the larger-sized (> 3 µm) phytoplankton than pico-phytoplankton (< 3 µm), indicating significant size-selective grazing by microzooplankton on the larger-sized phytoplankton, were also observed. The µ and m were significantly correlated with seawater salinity and temperature, and phytoplankton biomass, which indicated that salient seasonal variations in the phytoplankton growth and microzooplankton grazing in the SSCS were closely related to the environmental variables under the influence of the East Asian monsoon. We propose that intermittent arrivals of the northeast winter monsoon could lead to the low µ and m, and the decoupling between the µ and m in the SSCS, through influencing nutrient supply to the surface water, and inducing surface seawater salinity decrease. The low m/µ (< 50 % on average) indicates low remineralization of organic matter mediated by microzooplankton and mismatch between the µ and m, and thus probably accounts for part of the high vertical biogenic particle fluxes in the prevailing periods of the monsoons in the SSCS. The size-selective grazing suggests that microzooplankton grazing partially contributes to the pico-phytoplankton dominance in the oligotrophic tropical waters such as that of the SSCS.

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Section: Phytoplankton Growth and Microzooplankton Grazing Rates In Lsupporting

confidence: 56%

Seasonal and size-dependent variations in the phytoplankton growth and microzooplankton grazing in the southern South China Sea under the influence of the East Asian monsoon

et al. 2015

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“…At prey concentrations similar to the densities common in boreal lakes in spring (Ventelä 1999, Jasser & Arvola 2003, the loss of picoalgae due to mixed HNF culture was 10%, compared with 17 to 56% due to total microzooplankton grazing reported in natural environments (Kimmance et al 2007). The in situ grazing rates of HNF on picoalgae vary from 0.08 to 1.78 d -1 (Hirose et al 2008), compared with 0.96 to 2.40 d -1 obtained in laboratory experiments (Christaki et al 2005). Our results fall into the laboratory-derived range, showing that HNF have a high potential for grazing of picoalgae.…”

Section: Discussionsupporting

confidence: 47%

Grazing of heterotrophic nanoflagellates on the eukaryotic picoautotroph Choricystis sp.

Brek-Laitinen¹,

Ojala

2011

Aquat. Microb. Ecol.

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Autotrophic picoplankton (APP, < 2 µm), composed of both prokaryotes and eukaryotes, play an important role in the production and transformation of organic carbon in freshwaters. Eukaryotic APP are commonly found in winter and spring, and heterotrophic nanoflagellates (HNF) are regarded as significant consumers of APP. Here, we analysed the grazing impact and the growth ability of the HNF culture derived from a boreal clearwater lake on the picoalga Choricystis sp. For comparison, we used HNF monocultures of Rhynchomonas sp. and Bodo saltans flagellates with distinct feeding behaviours. In the grazing experiments, all HNF cultures ingested picoalgae and reached feeding rates between 0.08 and 0.81 cells HNF -1 h -1. We observed large species-specific differences in grazing rate (0.97 to 1.96 d ) in the growth experiments. Surprisingly, we found an increase in picoalgal growth in the presence of a grazing HNF population. Although HNF appear to be active herbivores capable of significantly reducing APP stock, flagellates were unable to control the picoalgal population. Overall, this study demonstrates an unexpected role of HNF in microbial food webs by imposing a positive feedback on picoalgal growth through grazing.KEY WORDS: Heterotrophic nanoflagellates · Picoeukaryotes · Grazing · Choricystis sp. · Rhynchomonas sp. · Bodo saltans Resale or republication not permitted without written consent of the publisherAquat Microb Ecol 62: [49][50][51][52][53][54][55][56][57][58][59] 2011 plankton (Christaki et al. 2001), thereby forming the major pathway of picoalgal carbon transport to higher trophic levels (Stockner 1988). Knowledge about grazing on eukaryotic APP is limited, and the majority of studies have concentrated on prokaryotic Synechococcus and Prochlorococcus (Worden et al. 2004). To the best of our knowledge, only 2 studies to date (Parslow et al. 1986, Christaki et al. 2005 have reported species-specific grazing of nanoflagellates on eukaryotic picoalgae, both in marine environments, while no parallel data on the grazing of freshwater HNF on Choricystis exist.Grazing studies have mainly been based on such approaches as size fractionation, dilution, use of specific inhibitors or disappearance of prey analogues (Caron et al. 1991, Liu et al. 1995, Worden & Binder 2003. However, these methods rely on communities and do not consider the different feeding modes of HNF. Investigation of prey items in the food vacuole of a single flagellate at a high resolution enables calculations of ingestion and clearance rates . Additionally, chlorophyll-containing autofluorescing cells of APP can easily be seen in food vacuoles of HNF without using fluorescing dyes (Dolan & 2imek 1998).Here we quantified the grazing impact of HNF on eukaryotic APP and also examined the potential of HNF to control APP at low temperatures. Our simple 2-step experimental set-up consisted of 1 defined prey item, i.e. a rod-shaped unicellular Choricystis sp., and 3 different types of HNF as grazers, i.e. Bodo saltans Ehrenberg, Rhyncho...

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“…Organisms less than 3 µm in size may be responsible for large part of primary production, in particular in oligotrophic areas (Platt et al ., 1983). Autotrophic as well as heterotrophic pico‐ and nanoplankton are too small to be efficiently consumed by metazoans (Sherr and Sherr, 1988); they are mainly consumed by flagellates and ciliates (Sherr and Sherr, 1994) and can significantly contribute to their diet (Hirose et al ., 2008). However, the grazing yield from phytoplankton is lower than from bacteria.…”

Section: Introductionmentioning

confidence: 99%

Pelagic food web patterns: do they modulate virus and nanoflagellate effects on picoplankton during the phytoplankton spring bloom?

Ory

Hartmann

Jude

et al. 2010

Environmental Microbiology

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As agents of mortality, viruses and nanoflagellates impact on picoplankton populations. We examined the differences in interactions between these compartments in two French Atlantic bays. Microbes, considered here as central actors of the planktonic food web, were first monitored seasonally in Arcachon (2005) and Marennes-Oléron (2006) bays. Their dynamics were evaluated to categorize trophic periods using the models of Legendre and Rassoulzadegan as a reference framework. Microbial interactions were then compared through 48 h batch culture experiments performed during the phytoplankton spring bloom, identified as herbivorous in Marennes and multivorous in Arcachon. Marennes was spatially homogeneous compared with Arcachon. The former was potentially more productive, featuring a large number of heterotrophic pathways, while autotrophic mechanisms dominated in Arcachon. A link was found between viruses and phytoplankton in Marennes, suggesting a role of virus in the regulation of autotroph biomass. Moreover, the virus-bacteria relation was weaker in Marennes, with a bacterial lysis potential of 2.6% compared with 39% in Arcachon. The batch experiments (based on size-fractionation and viral enrichment) revealed different microbial interactions that corresponded to the spring-bloom trophic interactions in each bay. In Arcachon, where there is a multivorous web, flagellate predation and viral lysis acted in an opposite way on picophytoplankton. When together they both reduced viral production. Conversely, in Marennes (herbivorous web), flagellates and viruses together increased viral production. Differences in the composition of the bacterial community composition explained the combined flagellate-virus effects on viral production in the two bays.

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Growth and grazing mortality rates of Prochlorococcus, Synechococcus and eukaryotic picophytoplankton in a bay of the Uwa Sea, Japan

Cited by 28 publications

References 60 publications

Seasonal and size-dependent variations in the phytoplankton growth and microzooplankton grazing in the southern South China Sea under the influence of the East Asian monsoon

Seasonal and size-dependent variations in the phytoplankton growth and microzooplankton grazing in the southern South China Sea under the influence of the East Asian monsoon

Grazing of heterotrophic nanoflagellates on the eukaryotic picoautotroph Choricystis sp.

Pelagic food web patterns: do they modulate virus and nanoflagellate effects on picoplankton during the phytoplankton spring bloom?

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