Prevalence of chytrid parasitism among diatom populations in the lower Columbia River (2009–2013)

Michelle A. Maier, Tawnya Peterson

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

We documented temporal (2009–2013) and spatial [river kilometre (rkm) 8–rkm 196] patterns of parasitic fungal infections on diatoms in the lower Columbia River, as evidenced by the presence of sporangia attached to diatom frustules. Multiple diatom species were infected by zoosporic fungi (‘chytrids’) throughout the year, with a maximum infection prevalence (Ip) among large diatoms of 36% in spring 2011. At a fixed site at rkm 85, up to 30–45% of the population of Asterionella formosa, the dominant spring diatom, was infected each year during the spring (2010–2013). During this time, high Ip was associated with high host density, low precipitation and low orthophosphate concentrations. Parasite load – the number of sporangia per infected diatom cell, also referred to as the mean intensity of infection, ī – increased with infection prevalence, but the population average never exceed two parasites per host. Net growth rates of chytrid populations exceeded those of A. formosa host diatoms in the spring under low-flow conditions. In spring 2013, the prevalence of infection increased from 35 to 78% and the parasite load increased from 1.5 to 2.2 along a downstream transect, suggesting that zoospores were actively infecting hosts in situ and not simply transported allochthonously. The estimated loss of organic carbon associated with diatoms via the parasitic pathway was greatest in spring (averaging c. 10%), with a peak of c. 85 μg carbon L−1 (c. 45% of total large-diatom carbon) lost from the diatom carbon pool to parasitism in May 2011. Parasites of microalgae may actively shape aquatic food webs within systems like the Columbia River by increasing the availability of large-diatom carbon to higher trophic levels, thus decreasing downstream export losses to the estuary and coastal ocean.

Original languageEnglish (US)
Pages (from-to)414-428
Number of pages15
JournalFreshwater Biology
Volume62
Issue number2
DOIs
StatePublished - Feb 1 2017

Fingerprint

Columbia River
Bacillariophyceae
parasitism
diatom
river
Asterionella formosa
infection
parasite intensity
parasite load
sporangia
carbon
parasite
aquatic food webs
parasites
rivers
orthophosphates
zoospores
orthophosphate
microalgae
carbon sinks

Keywords

  • Asterionella formosa
  • chytrid
  • Columbia River
  • diatom
  • parasite

ASJC Scopus subject areas

  • Aquatic Science

Cite this

Prevalence of chytrid parasitism among diatom populations in the lower Columbia River (2009–2013). / Maier, Michelle A.; Peterson, Tawnya.

In: Freshwater Biology, Vol. 62, No. 2, 01.02.2017, p. 414-428.

Research output: Contribution to journalArticle

@article{433e13ab76224a6092bbb08e34cb2395,
title = "Prevalence of chytrid parasitism among diatom populations in the lower Columbia River (2009–2013)",
abstract = "We documented temporal (2009–2013) and spatial [river kilometre (rkm) 8–rkm 196] patterns of parasitic fungal infections on diatoms in the lower Columbia River, as evidenced by the presence of sporangia attached to diatom frustules. Multiple diatom species were infected by zoosporic fungi (‘chytrids’) throughout the year, with a maximum infection prevalence (Ip) among large diatoms of 36{\%} in spring 2011. At a fixed site at rkm 85, up to 30–45{\%} of the population of Asterionella formosa, the dominant spring diatom, was infected each year during the spring (2010–2013). During this time, high Ip was associated with high host density, low precipitation and low orthophosphate concentrations. Parasite load – the number of sporangia per infected diatom cell, also referred to as the mean intensity of infection, ī – increased with infection prevalence, but the population average never exceed two parasites per host. Net growth rates of chytrid populations exceeded those of A. formosa host diatoms in the spring under low-flow conditions. In spring 2013, the prevalence of infection increased from 35 to 78{\%} and the parasite load increased from 1.5 to 2.2 along a downstream transect, suggesting that zoospores were actively infecting hosts in situ and not simply transported allochthonously. The estimated loss of organic carbon associated with diatoms via the parasitic pathway was greatest in spring (averaging c. 10{\%}), with a peak of c. 85 μg carbon L−1 (c. 45{\%} of total large-diatom carbon) lost from the diatom carbon pool to parasitism in May 2011. Parasites of microalgae may actively shape aquatic food webs within systems like the Columbia River by increasing the availability of large-diatom carbon to higher trophic levels, thus decreasing downstream export losses to the estuary and coastal ocean.",
keywords = "Asterionella formosa, chytrid, Columbia River, diatom, parasite",
author = "Maier, {Michelle A.} and Tawnya Peterson",
year = "2017",
month = "2",
day = "1",
doi = "10.1111/fwb.12876",
language = "English (US)",
volume = "62",
pages = "414--428",
journal = "Freshwater Biology",
issn = "0046-5070",
publisher = "Wiley-Blackwell",
number = "2",

}

TY - JOUR

T1 - Prevalence of chytrid parasitism among diatom populations in the lower Columbia River (2009–2013)

AU - Maier, Michelle A.

AU - Peterson, Tawnya

PY - 2017/2/1

Y1 - 2017/2/1

N2 - We documented temporal (2009–2013) and spatial [river kilometre (rkm) 8–rkm 196] patterns of parasitic fungal infections on diatoms in the lower Columbia River, as evidenced by the presence of sporangia attached to diatom frustules. Multiple diatom species were infected by zoosporic fungi (‘chytrids’) throughout the year, with a maximum infection prevalence (Ip) among large diatoms of 36% in spring 2011. At a fixed site at rkm 85, up to 30–45% of the population of Asterionella formosa, the dominant spring diatom, was infected each year during the spring (2010–2013). During this time, high Ip was associated with high host density, low precipitation and low orthophosphate concentrations. Parasite load – the number of sporangia per infected diatom cell, also referred to as the mean intensity of infection, ī – increased with infection prevalence, but the population average never exceed two parasites per host. Net growth rates of chytrid populations exceeded those of A. formosa host diatoms in the spring under low-flow conditions. In spring 2013, the prevalence of infection increased from 35 to 78% and the parasite load increased from 1.5 to 2.2 along a downstream transect, suggesting that zoospores were actively infecting hosts in situ and not simply transported allochthonously. The estimated loss of organic carbon associated with diatoms via the parasitic pathway was greatest in spring (averaging c. 10%), with a peak of c. 85 μg carbon L−1 (c. 45% of total large-diatom carbon) lost from the diatom carbon pool to parasitism in May 2011. Parasites of microalgae may actively shape aquatic food webs within systems like the Columbia River by increasing the availability of large-diatom carbon to higher trophic levels, thus decreasing downstream export losses to the estuary and coastal ocean.

AB - We documented temporal (2009–2013) and spatial [river kilometre (rkm) 8–rkm 196] patterns of parasitic fungal infections on diatoms in the lower Columbia River, as evidenced by the presence of sporangia attached to diatom frustules. Multiple diatom species were infected by zoosporic fungi (‘chytrids’) throughout the year, with a maximum infection prevalence (Ip) among large diatoms of 36% in spring 2011. At a fixed site at rkm 85, up to 30–45% of the population of Asterionella formosa, the dominant spring diatom, was infected each year during the spring (2010–2013). During this time, high Ip was associated with high host density, low precipitation and low orthophosphate concentrations. Parasite load – the number of sporangia per infected diatom cell, also referred to as the mean intensity of infection, ī – increased with infection prevalence, but the population average never exceed two parasites per host. Net growth rates of chytrid populations exceeded those of A. formosa host diatoms in the spring under low-flow conditions. In spring 2013, the prevalence of infection increased from 35 to 78% and the parasite load increased from 1.5 to 2.2 along a downstream transect, suggesting that zoospores were actively infecting hosts in situ and not simply transported allochthonously. The estimated loss of organic carbon associated with diatoms via the parasitic pathway was greatest in spring (averaging c. 10%), with a peak of c. 85 μg carbon L−1 (c. 45% of total large-diatom carbon) lost from the diatom carbon pool to parasitism in May 2011. Parasites of microalgae may actively shape aquatic food webs within systems like the Columbia River by increasing the availability of large-diatom carbon to higher trophic levels, thus decreasing downstream export losses to the estuary and coastal ocean.

KW - Asterionella formosa

KW - chytrid

KW - Columbia River

KW - diatom

KW - parasite

UR - http://www.scopus.com/inward/record.url?scp=85008953040&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85008953040&partnerID=8YFLogxK

U2 - 10.1111/fwb.12876

DO - 10.1111/fwb.12876

M3 - Article

AN - SCOPUS:85008953040

VL - 62

SP - 414

EP - 428

JO - Freshwater Biology

JF - Freshwater Biology

SN - 0046-5070

IS - 2

ER -