Role of heterotrophic dinoflagellate <i>Gyrodinium</i> sp. in the fate of an iron induced diatom bloom

Saito, Hiroaki; Ota, Takashi; Suzuki, Koji; Nishioka, Jun; Tsuda, Atsushi

doi:10.1029/2005gl025366

Cited by 61 publications

(48 citation statements)

References 24 publications

(28 reference statements)

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“…This observation is consistent with certain feeding strategies being more favorable than others at different times of the year, but more extensive observations are needed to determine if recurrent patterns occur seasonally. Heterotrophic dinoflagellates, such as Gyrodinium spp., have been observed to feed on a wide range of prey types, from pure autotrophs to other heterotrophic organisms such as bacteria and small flagellates (Gaines & Elbrachter 1987, Jacobson 1987, Hansen 1992, Saito et al 2006, Jeong et al 2008. Though dinoflagellates have been observed to be dominant grazers on diatoms (Sherr & Sherr 2007), this may not always be the case in waters near Woods Hole.…”

Section: Discussionmentioning

confidence: 96%

Microzooplankton community structure investigated with imaging flow cytometry and automated live-cell staining

Brownlee

Olson²,

Sosik³

2016

Mar. Ecol. Prog. Ser.

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Protozoa play important roles in grazing and nutrient recycling, but quantifying these roles has been hindered by difficulties in collecting, culturing, and observing these often-delicate cells. During long-term deployments at the Martha's Vineyard Coastal Observatory (Massachusetts, USA), Imaging FlowCytobot (IFCB) has been shown to be useful for studying live cells in situ without the need to culture or preserve. IFCB records images of cells with chlorophyll fluorescence above a trigger threshold, so to date taxonomically resolved analysis of protozoa has presumably been limited to mixotrophs and herbivores which have eaten recently. To overcome this limitation, we have coupled a broad-application 'live cell' fluorescent stain with a modified IFCB so that protozoa which do not contain chlorophyll (such as consumers of unpigmented bacteria and other heterotrophs) can also be recorded. Staining IFCB (IFCB-S) revealed higher abundances of grazers than the original IFCB, as well as some cell types not previously detected. Feeding habits of certain morphotypes could be inferred from their fluorescence properties: grazers with stain fluorescence but without chlorophyll cannot be mixotrophs, but could be either starving or feeding on heterotrophs. Comparisons between cell counts for IFCB-S and manual light microscopy of Lugol's stained samples showed consistently similar or higher counts from IFCB-S. We show how automated classification through the extraction of image features and application of a machine-learning algorithm can be used to evaluate the large high-resolution data sets collected by IFCBs; the results reveal varying seasonal patterns in abundance among groups of protists.

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Section: Discussionmentioning

confidence: 96%

Microzooplankton community structure investigated with imaging flow cytometry and automated live-cell staining

Brownlee

Olson²,

Sosik³

2016

Mar. Ecol. Prog. Ser.

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“…However, an important part of total marine primary production is due to mass phytoplankton blooms dominated by the large-sized and chain-forming species of diatoms which characterize spring and upwelling blooms (Sarthou et al 2005, Barber & Hiscock 2006. Large-sized diatoms also dominate blooms induced by experimental addition of iron in HNLC regions of the sea (Saito et al 2006, Barber & Hiscock 2006 and those episodically observed as a consequence of eddy-driven upwelling (Falkowski et al 1991, McGillicuddy et al 2007. Marine diatom blooms are responsible for most export production, which is significant in terms of both organic sinking flux and food webs supporting marine fisheries (Iverson 1990, Barber & Hiscock 2006.…”

Section: Phytoplankton Blooms In Ocean Ecosystemsmentioning

confidence: 99%

“…Such increasing ratios suggest limitation of microzooplankton biomass during and after bloom peaks. Phytoplankton blooms may be grazed down to some extent by microzooplankton, as described by Tillmann (2004) for coastal blooms of single-cell Phaeocystis sp., and by Saito et al (2006) and Suffrian et al (2008) for a nutrient-stimulated diatom blooms, if protist biomass is not strongly topdown controlled.…”

Section: Top-down Control Of Microzooplankton Biomassmentioning

confidence: 99%

Capacity of herbivorous protists to control initiation and development of mass phytoplankton blooms

Sherr¹,

Sherr²

2009

Aquat. Microb. Ecol.

112

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Microzooplankton, heterotrophic organisms 20 to 200 µm in size and mainly phagotrophic protists, are recognized as the dominant consumers of phytoplankton in all regions of the sea. During his long career, Fereidoun Rassoulzadegan has been a major contributor to the understanding of the importance of protists in marine pelagic food webs. In the spirit of his research, we consider here one aspect of microzooplankton ecology that, in our opinion, has been misunderstood: the capacity of protist herbivores to control initiation and development of mass phytoplankton blooms, with a focus on diatom blooms. We argue that microzooplankton grazers probably cannot prevent bloom initiation and out-growth during mesotrophic to eutrophic conditions. We base our contention on the propositions that (1) mass diatom blooms do, in fact, routinely occur in the ocean at all latitudes; (2) since prey abundance is a main factor controlling protist growth, the grazing impact of herbivorous protists will be minor in the early stages of a bloom when prey abundances and, therefore, protist growth rates, are low; (3) due to food limitation during pre-bloom conditions, protist biomass will usually be low at the onset of a bloom, which serves to limit initial grazing impact; and (4) biomass of herbivorous protists is ultimately top-down controlled, thus curtailing the potential for microzooplankton to grow to sufficient abundance to graze down a developed bloom. We conclude that herbivorous protists are not likely to be able to prevent the initiation and development of mass blooms when conditions are favorable for rapid phytoplankton growth.

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“…They also produce detrital bSiO 2 , which promotes the recycling of Si(OH) 4 in the microbial loop (Schultes et al, 2010). For example, when pallium-feeding thecate dinoflagellates feed on diatoms, they discard the empty silica frustules (Jacobson and Anderson, 1986), whereas athecate dinoflagellates, which directly ingest diatoms, produce mini-fecal pellets composed of the frustules with little associated carbon (Buck and Newton, 1995;Strom and Strom, 1996;Saito et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Effect of the Silica Content of Diatoms on Protozoan Grazing

Zhang

Liu

et al. 2017

Front. Mar. Sci.

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This study examined the effect that silica content in diatom cells has on the behavior of protists. The diatoms Thalassiosira weissflogii and T. pseudonana were cultured in high or low light conditions to achieve low and high silica contents, respectively. These cells were then fed to a heterotrophic dinoflagellate Noctiluca scintillans and a ciliate Euplotes sp. in single and mixed diet experiments. Our results showed that in general, N. scintillans and Euplotes sp. both preferentially ingested the diatoms with a low silica content rather than those with a high silica content. However, Euplotes sp. seemed to be less influenced by the silica content than was N. scintillans. In the latter case, the clearance and ingestion rate of the low silica diatoms were significantly higher, both in the short (6-h) and long (1-d) duration grazing experiments. Our results also showed that N. scintillans required more time to digest the high silica-containing cells. As the high silica diatoms are harder to digest, this might explain why N. scintillans exhibits a strong preference for the low silica prey. Thus, the presence of high silica diatoms might limit the ability of the dinoflagellate to feed. Our findings suggest that the silica content of diatoms affects their palatability and digestibility and, consequently, the grazing activity and selectivity of protozoan grazers.

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Role of heterotrophic dinoflagellate Gyrodinium sp. in the fate of an iron induced diatom bloom

Cited by 61 publications

References 24 publications

Microzooplankton community structure investigated with imaging flow cytometry and automated live-cell staining

Microzooplankton community structure investigated with imaging flow cytometry and automated live-cell staining

Capacity of herbivorous protists to control initiation and development of mass phytoplankton blooms

Effect of the Silica Content of Diatoms on Protozoan Grazing

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