Diel changes in phagotrophy by Cryptomonas in Lake Biwa

Urabe, Jotaro; Gurung, Tek Bahadur; Yoshida, Takehito; Sekino, Tatsuki; Nakanishi, Masami; Maruo, Masahiro; Nakayama, Eiichiro

doi:10.4319/lo.2000.45.7.1558

Cited by 63 publications

(61 citation statements)

References 25 publications

(48 reference statements)

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“…The negative correlation between cryptophytes grazing rates and nutrient concentrations is in accordance with the conclusions achieved by Urabe et al (2000) in Lake Biwa, which claimed that cryptophytes use phagotrophy as an alternative source of nutrients. Interestingly, CR and CSGR of cryptophytes in our experiments were also highly positively correlated with estimators of the in situ light condition: Secchi depth and photoperiod (defined as the number of hours of sunlight per day).…”

Section: Factors Controlling Ingestion Rates In the Dominant Mixotrophssupporting

confidence: 78%

“…Then, the time elapsed from sampling and the start of the experiment, would have probably been too short to allow the cells to adapt to the in vitro light conditions. Urabe et al (2000) and På lsson and Grané li (2003) observed that different species of freshwater Cryptomonas exhibited significant diurnal differences in bacterial ingestion rates, with the lowest values recorded during the night. These results suggest that phagotrophy in these organisms would be light dependent and that they might not survive using bacterivory as the unique mode of nutrition.…”

Section: Factors Controlling Ingestion Rates In the Dominant Mixotrophsmentioning

confidence: 99%

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Mixotrophic haptophytes are key bacterial grazers in oligotrophic coastal waters

et al. 2013

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Grazing rate estimates indicate that approximately half of the bacterivory in oligotrophic oceans is due to mixotrophic flagellates (MFs). However, most estimations have considered algae as a single group. Here we aimed at opening the black-box of the phytoflagellates (PFs) o20 lm. Haptophytes, chlorophytes, cryptophytes and pigmented dinoflagellates were identified using fluorescent in situ hybridization or by standard 4 0 ,6-diamidino-2-phenylindole staining. Their fluctuations in abundance, cell size, biomass and bacterivory rates were measured through an annual cycle in an oligotrophic coastal system. On average, we were able to assign to these groups: 37% of the total pico-PFs and 65% of the nano-PFs composition. Chlorophytes were mostly picoplanktonic and they never ingested fluorescently labeled bacteria. About 50% of the PF o20 lm biomass was represented by mixotrophic algae. Pigmented dinoflagellates were the least abundant group with little impact on bacterioplankton. Cryptophytes were quantitatively important during the coldest periods and explained about 4% of total bacterivory. Haptophytes were the most important mixotrophic group: (i) they were mostly represented by cells 3-5 lm in size present year-round; (ii) cell-specific grazing rates were comparable to those of other bacterivorous non-photosynthetic organisms, regardless of the in situ nutrient availability conditions; (iii) these organisms could acquire a significant portion of their carbon by ingesting bacteria; and (iv) haptophytes explained on average 40% of the bacterivory exerted by MFs and were responsible for 9-27% of total bacterivory at this site. Our results, when considered alongside the widespread distribution of haptophytes in the ocean, indicate that they have a key role as bacterivores in marine ecosystems.

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Section: Factors Controlling Ingestion Rates In the Dominant Mixotrophssupporting

confidence: 78%

Section: Factors Controlling Ingestion Rates In the Dominant Mixotrophsmentioning

confidence: 99%

Mixotrophic haptophytes are key bacterial grazers in oligotrophic coastal waters

et al. 2013

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“…The dominance of Cryptophyceae on different sampling dates, can be explained by the fact that Cryptomonas marsonii and C. cf. obovata (Y FG), are typical mixotrophic flagellated organisms that can withstand occasional nitrogen and light limitation, as they can ingest bacteria (Tranvik et al, 1989;Jones, 2000;Urabe et al, 2000;Sinistro et al, 2007;Unrein et al, 2007;Allende et al, 2009). This fact, and the capacity to migrate vertically in order to reach optimum light condition, allowed them to remain in the water column during the whole phytoplankton succession, and to reach a greater contribution when macrophyte cover was more profuse and/or DIN concentration was low in the late re-flooding period.…”

Section: Discussionmentioning

confidence: 99%

Influence of re-flooding on phytoplankton assemblages in a temperate wetland following prolonged drought

Avigliano¹,

Vinocur²,

Chaparro³

et al. 2014

J Limnol

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“…(Cryptophyte) and Dinobryon spp. (Chrysophyte), have been show to exhibit significant diurnal differences in bacterial ingestion rates, with the highest rates measured in late afternoon (Urabe et al 2000;På lsson and Granéli 2003). Experimental evidences obtained in vitro with cultures of mixotrophic chrysophytes (Dinobryon cylindricum) and haptophytes (Chrysocromulina ericina) have also demonstrated that higher biomass, cell density, or growth rates are usually achieved in light conditions as compared to darkness (Caron et al 1993;Hansen and Hjorth 2002).…”

Section: Relative Grazing Effect Of the Different Flagellate Types-mentioning

confidence: 99%

“…Mixotrophy, defined here as the combination of photosynthesis and particle grazing (sensu Sanders 1991), has been observed in most phytoflagellated groups: chrysophytes (Bird and Kalff 1986), dinoflagellates (Stoecker et al 1997), cryptophytes (Urabe et al 2000), dictyochophytes (Nygaard and Tobiesen 1993), euglenophytes (Epstein and Shiaris 1992), and haptophytes (Skovgaard et al 2003). Although the ability to ingest particulate material by unicellular algae had been described almost one century ago (Biecheler 1936), the potential significance of this behavior for the elemental flow through the microbial food web was recognized only during the last two decades (Sanders 1991).…”

mentioning

confidence: 99%

Significant year‐round effect of small mixotrophic flagellates on bacterioplankton in an oligotrophic coastal system

Unrein

Massana

Alonso‐Sáez

et al. 2007

Limnology & Oceanography

207

186

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The seasonal variation in the grazing effect of mixotrophic flagellates on bacterioplankton was assessed during an annual cycle in an oligotrophic coastal station in the northwest Mediterranean Sea. Ingestion rates of fluorescently labeled bacteria were estimated for different size categories of phytoflagellates (PF) and heterotrophic flagellates (HF) in short-term experiments and compared with long-term grazing estimates and published empirical models. The mixotrophic flagellates included haptophyte-like cells, cryptophytes, and dinoflagellates. The group-specific grazing rates (SGR) averaged 1.1 (3-5 mm PF), 1.3 (5-20 mm PF), 4.0 (,5 mm HF), and 15.4 bacteria individual 21 h 21 (5-20 mm HF). Lower SGR but higher abundances of PF resulted in an average mixotroph contribution of 50% to the total flagellate grazing. Remarkably, the effect was relatively high all through the year (35-65%). Regardless of the presence of chloroplasts, flagellates ,5 mm in size accounted, on average, for about 80% of total flagellate bacterivory and ingested a large percentage of their cell carbon per day from bacteria. Soluble reactive phosphorus concentration was negatively correlated with the ingestion rate of both groups of PF, suggesting that mixotrophic flagellates would be using their phagotrophic capability to obtain phosphorus when this nutrient is limiting. HF grazing activity showed a marked seasonality, with grazing being higher during the warmer seasons, and clearance rates were positively correlated with water temperature. Total bacterivory accounted for most of the bacterial production. Short-term and long-term bacterivory measurements were highly correlated, confirming that the smallest flagellates were the main causative agent of bacterial loss. The bacterivory values were also well correlated to a published empirical model that considers HF as the only bacterivorous. However, this model underestimated (up to 50%) total flagellate grazing during periods of high effect of mixotrophic flagellates.

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Diel changes in phagotrophy by Cryptomonas in Lake Biwa

Cited by 63 publications

References 25 publications

Mixotrophic haptophytes are key bacterial grazers in oligotrophic coastal waters

Mixotrophic haptophytes are key bacterial grazers in oligotrophic coastal waters

Influence of re-flooding on phytoplankton assemblages in a temperate wetland following prolonged drought

Significant year‐round effect of small mixotrophic flagellates on bacterioplankton in an oligotrophic coastal system

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