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{| class="model-ib" style="float:right; margin-left:1em; margin-bottom:1em;" ! Bacterivory (radiolabelled prey surrogates) |- | '''Approach:''' ³H or ¹⁴C radiolabelled bacteria; filtration and scintillation counting |- | '''Context:''' incubation |- | ''..."

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Created page with "{{BreadcrumbsInteractions}} * Page authors: PRIMO * Responsible curator: Hagen Buck-Wiese ---- __TOC__ <div class="model-box"> {| class="model-ib" style="float:right; margin-left:1em; margin-bottom:1em;" ! Bacterivory (radiolabelled prey surrogates) |- | '''Approach:''' 3H or 14C radiolabelled bacteria; filtration and scintillation counting |- | '''Context:''' incubation |- | ''..."

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* [[Page authors|Page authors]]: [[PRIMO]]
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{| class="model-ib" style="float:right; margin-left:1em; margin-bottom:1em;"
! Bacterivory (radiolabelled prey surrogates)
|-
| '''Approach:''' 3H or 14C radiolabelled bacteria; filtration and scintillation counting
|-
| '''Context:''' incubation
|-
| '''Spatial scale:''' point sample
|-
| '''Temporal scale:''' minutes to hours
|-
| '''Units:''' prey cell-1 h-1
|-
| '''Community captured:''' bulk protistan grazers
|-
| '''Co-measurements:''' abundances of predator and prey; carbon content
|}
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== Method Overview ==

Bacteria are radiolabelled by growing them in the presence of 3H-thymidine or 14C-substrates, so that their DNA or biomass carries a radioactive label. These labelled bacteria are added to seawater samples at near-natural densities and allowed to be consumed by protistan grazers during a short incubation. After incubation, samples are filtered through two successive filters: larger pores (e.g., 1 µm) retain the protistan grazers while allowing unlabelled and labelled bacterial prey to pass; the filtrate is then passed through a smaller filter retaining bacteria. Radioactivity on the large-pore filter (protists with ingested labelled bacteria) is measured by liquid scintillation counting and converted to ingestion rates<ref name="Taylor1984">Taylor, W. D., & Sullivan, C. W. (1984). The use of 14C-labeled bacteria as a tracer of ingestion and metabolism of bacterial biomass by microbial grazers. ''Journal of Microbiological Methods'', 3(2), 101–124. https://doi.org/10.1016/0167-7012(84)90011-3</ref>.

=== Scale of measurement ===

Discrete samples collected after short incubation (minutes to one hour).

=== Data generated ===

Bulk ingestion rate of radiolabelled bacteria by the protistan community (cells L-1 h-1 or ng C L-1 h-1).

=== Units & currency ===

Units are prey cell-1 h-1. The currency is cells.

=== Sample size ===

Typical samples are < 1 L in volume.

=== Repositories & databases ===

== Limitations ==

The method assumes no selective grazing, i.e., that the radiolabelled prey are consumed at the same rate as natural bacteria. Good separation of labelled bacterial prey (passing through the filter) and protistan predators (retained on the filter) must be verified; any labelled bacteria retained on the larger-pore filter inflate apparent grazing. The approach provides community-level rates and cannot resolve which individual predator taxa are grazing.

== Example Applications & Protocols ==

=== Classic examples ===
* Taylor & Sullivan (1984) ''The use of 14C-labeled bacteria as a tracer of ingestion and metabolism of bacterial biomass by microbial grazers'' <ref name="Taylor1984" />

=== Recent applications ===
*

=== Common calculations/conversions ===
* Ingestion rate = (cpmgrazer filter / cpmlabeled bacteria per cell) / (predator abundance × incubation time).

== References ==

[[Category:Main Pages|Model types]]

Radioactively labeled prey surrogates - Revision history