Enumeration of parasitic chytrid zoospores in the Columbia River via quantitative PCR

Michelle A. Maier, Tawnya Peterson

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Through lethal infection, fungal parasites of phytoplankton ("chytrids") repackage organic material from the large, effectively inedible, colonial diatoms they infect into much smaller zoospores, which are easier for zooplankton to consume. However, their small size and lack of distinguishing morphological features render it difficult to distinguish zoospores from other small flagellates in mixed assemblages in the natural environment. In this study, we developed and tested a method to quantify chytrid zoospores in field studies using quantitative PCR (qPCR) targeting the internal transcribed spacer 2 (ITS2) region within the rRNA gene cluster. To achieve accurate quantification, the assay was designed to be highly specific for a parasite (Rhizophydium planktonicum) of the diatom Asterionella formosa; however, the approach is applicable to additional host-parasite systems. Parasitic zoospores were detected and quantified in the freshwater reaches of the lower Columbia River, as well as in the salt-influenced estuary and river plume. The coincidence between zoospore abundances and a prevalence of small zooplankton during blooms of large, colonial diatoms in the spring suggests that Columbia River zooplankton may be poised to benefit nutritionally from chytrid zoospores, thus providing a mechanism to retain organic carbon within the system and reduce losses to downstream export. We estimate that~15% of the carbon biomass tied up in blooms of the dominant diatom species is transformed into zoospores through the parasitic shunt during spring.

Original languageEnglish (US)
Pages (from-to)3857-3867
Number of pages11
JournalApplied and Environmental Microbiology
Volume82
Issue number13
DOIs
StatePublished - 2016

Fingerprint

Diatoms
Columbia River
zoospores
Zooplankton
Rivers
quantitative polymerase chain reaction
diatom
Bacillariophyceae
Polymerase Chain Reaction
zooplankton
parasite
Parasites
river
algal bloom
Carbon
Phytoplankton
Estuaries
river plume
parasites
flagellate

ASJC Scopus subject areas

  • Applied Microbiology and Biotechnology
  • Food Science
  • Biotechnology
  • Ecology

Cite this

Enumeration of parasitic chytrid zoospores in the Columbia River via quantitative PCR. / Maier, Michelle A.; Peterson, Tawnya.

In: Applied and Environmental Microbiology, Vol. 82, No. 13, 2016, p. 3857-3867.

Research output: Contribution to journalArticle

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