Paraphysomonas imperforata (Protista, Chrysomonadida) under different turbulence levels:feeding, physiology and energetics

Peters, Francesc; Choi, Joon W.; Gross, T.S.

doi:10.3354/meps134235

Cited by 17 publications

(15 citation statements)

References 20 publications

(36 reference statements)

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“…where T is the portion of the period following the passage of the grid that showed a trend of decreasing turbulent kinetic energy (Peters et al 1996). At each stroke frequency, 2 values of <E> were computed: 1 for the downward passage of the grid and 1 for the upward passage.…”

Section: Methodsmentioning

confidence: 99%

Feeding behaviour of Centropages typicus in calm and turbulent conditions

Caparroy¹,

Pérez²,

Carlotti³

1998

Mar. Ecol. Prog. Ser.

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Feeding of the copepod Centropages typicus on the oligotrich ciliate Strombidium sulcaturn was studied in the laboratory under controlled, measured conditions of grid generated small scale turbulence. High levels of turbulence, F (kinetic energy dissipation rate) = 2.9 X 10-2 to 3 X 10-' cm2 s3, increased the clearance rate of C. typicus feeding on S. sulcatum by up to a factor of 4 in comparison to calm water values. At a level of turbulence of 4.4 cm2 s -~, we observed a drastic decrease in clearance rates to values equivalent to those in calm water. We suggest an explanation for the observed changes in predation rates with levels of turbulence. Video recorded observations of the behaviour of free swimming C. typicus conducted in calm conditions suggest that the copepod uses a cruising strategy to search and encounter S. sulcatum. In the presence of this cillate, C. typlcus increases the proportion of time spent swimming at a mean velocity of 3.5 mm S-': from 49.5'% in filtered seawater without ciliates to 79.5% in the presence of S. sulcatum (1 cell ml-l). Furthermore, a qualitative change of the swimming behaviour is triggered by the presence of the ciliate, resulting in an increased proportion of time spent slow swimming in a 'helical' mode. Our results suggest that high levels of small scale turbulence substantially increase predation rates of crunsing copepods.

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Section: Methodsmentioning

confidence: 99%

Feeding behaviour of Centropages typicus in calm and turbulent conditions

Caparroy¹,

Pérez²,

Carlotti³

1998

Mar. Ecol. Prog. Ser.

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“…abundance, size, mobility, biochemical composition, physiological state, surface characteristics, grazing resistance properties) and variables independent of prey. Among the latter, temperature (Sherr et al 1988, Tobiesen 1990, light intensity (Stoecker & Guillard 1982, Hansen & Nielsen 1997, Strom 2001, ultraviolet radiation (Hessen et al 1997, Ochs & Eddy 1998, nutrient concentrations (Ucko et al 1994, Legrand et al 1998, Granéli & Johansson 2003, turbulence (Shimeta et al 1995, Peters et al 1996, Dolan et al 2003, suspended non-grazable particles (Hansen et al 1991, Boenigk & Novarino 2004, and particularly bioactive compounds and toxic compounds (Hoffman & Atlas 1987, Al-Rasheid & Sleigh 1994 can regulate feeding activity in phagotrophic protists, but their role in selective feeding has rarely been specifically investigated. Most of these abiotic external variables can either directly affect the feeding behaviour of phagotrophic protists, or indirectly influence them through changes upon their prey.…”

Section: Linking Food Selection With the Natural Environmentmentioning

confidence: 99%

Selective feeding behaviour of key free-living protists: avenues for continued study

Montagnes¹,

Barbosa²,

Boenigk³

et al. 2008

Aquat. Microb. Ecol.

174

154

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Phagotrophic protists are diverse and abundant in aquatic and terrestrial environments, making them fundamental to the transfer of matter/energy within their respective food webs. Recognising their grazing impact is essential to evaluate the role of protists in ecosystems, and this includes appreciating prey selectivity. Efforts have been made by groups and individuals to understand selective grazing behaviour by protists: many approaches and perspectives have been pursued, not all of which are compatible. This article, which is not a review, is the product of our discourse on this subject at the SAME 10 meeting. It is the work of individuals, assembled for their breadth of backgrounds, approaches, views, and expertise. Firstly, to communicate ideas and approaches, we develop a framework for selective feeding processes and suggest 6 steps: searching, contact, capture, processing, ingestion, digestion. We then separate study approaches into 2 categories: (1) those examining whole organisms at the community, population, and individual levels, and (2) those examining physiology and molecular attributes. Finally, we explore general problems associated with the field of protistan selective feeding (e.g. linking food selection into food webs and modeling). We do not present all views on any one topic, nor do we cover all topics; instead, we offer opinions and suggest avenues for continued study. Overall, this paper should stimulate further discourse on the subject and provide a roadmap for the future.

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“…In practice, GGEs for many protists do seem to vary considerably -even within the same species and despite efforts to conduct balanced-growth experiments (e.g. Verity 1985, Strom & Busky 1993, Peters et al 1996. Thus, other factors, such as food concentration or quality, apparently influence GGE.…”

Section: Flagellate Ggementioning

confidence: 99%

Heterotrophic nanoflagellate enhancement of bacterial growth through nutrient remineralization in chemostat culture

Selph¹,

Landry²

2003

Aquat. Microb. Ecol.

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Heterotrophic nanoflagellates are the principal consumers of picoplankton in the ocean. Their role as nutrient remineralizers is also well established. However, the coupled interactions between grazer consumption and prey growth are less well understood. In this work, we demonstrate a tight coupling among flagellate grazing, nitrogen remineralization, and prey growth, resulting in bacterial growth rates averaging 2-to 14-fold higher in the presence of flagellate grazers. These results were obtained using 2-stage, nitrogen-limited chemostats containing a mixed culture of heterotrophic bacteria enriched from seawater and Paraphysomonas bandaiensis, a chrysomonad flagellate. Abundance and biovolume of the flagellates were monitored on a daily basis, as was bacterial abundance. Grazing rates were measured using short-term tracer uptake experiments (fluorescently-labeled bacteria and beads), and these data were used to calculate gross bacterial growth rates in the presence of grazers. A mass balance approach was used to estimate reduced nitrogen regenerated by the protist and nitrogen demand of the heterotrophic bacteria. These independent methods of assessing grazer growth and feeding, coupled with estimates of flagellate gross growth efficiency, provided strong, internally consistent constraints on the estimates of bacterial growth rates in the presence of grazers. Under these culture conditions, P. bandaiensis had a carbon-based gross growth efficiency averaging 28%. This work shows that independently measured grazing rates are essential in protist culture work if system dynamics are to be understood. It also underscores the necessity of including protist remineralization pathways in models if realistic simulations are to be obtained.

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Paraphysomonas imperforata (Protista, Chrysomonadida) under different turbulence levels:feeding, physiology and energetics

Cited by 17 publications

References 20 publications

Feeding behaviour of Centropages typicus in calm and turbulent conditions

Feeding behaviour of Centropages typicus in calm and turbulent conditions

Selective feeding behaviour of key free-living protists: avenues for continued study

Heterotrophic nanoflagellate enhancement of bacterial growth through nutrient remineralization in chemostat culture

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