Effects of Heterosigma akashiwo (Raphidophyceae) on protist grazers: laboratory experiments with ciliates and heterotrophic dinoflagellates

Clough, Jennifer; Strom, Suzanne L.

doi:10.3354/ame039121

Cited by 34 publications

(36 citation statements)

References 57 publications

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“…Recently, H. akashiwo has been shown to induce sublethal effects in the oyster Crassostrea virginica (Keppler et al 2005) and to alter the metabolic activity of mammalian cells (Twiner et al 2004). At this time, there is no accepted chemical measure of toxin content in this species (Clough & Strom 2005).…”

Section: Introductionmentioning

confidence: 99%

“…Jeong et al (2002) found the prostomatid ciliate Tiarina fusus to exhibit positive growth when exposed to increasing concentrations of H. akashiwo. Clough & Strom (2005) showed that the tintinnid ciliate Eutintinnus sp. and the dinoflagellate Noctiluca scintillans derived nutritional benefit from 2 strains of H. akashiwo, while the ciliate Strombidium sp.…”

Section: Introductionmentioning

confidence: 99%

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Growth and grazing of microzooplankton in response to the harmful alga Heterosigma akashiwo in prey mixtures

Graham¹,

Strom²

2010

Aquat. Microb. Ecol.

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Microzooplankton grazers may play a role in regulating blooms of the ichthyotoxic alga Heterosigma akashiwo. This study tested the effects of H. akashiwo, when part of a mixed-prey assemblage, on the growth and feeding of microzooplankton. Laboratory cultures of 3 ciliates, Favella sp., Metacylis sp., and Strombidinopsis acuminatum, were exposed to reciprocal concentrations of H. akashiwo and a non-toxic prey, at saturating prey concentrations. Heterosigma akashiwo was toxic to Favella sp. and Metacylis sp. when H. akashiwo was the sole prey species; however, this toxicity was eliminated in the mixed-prey treatments, likely because of avoidance of H. akashiwo and selective feeding on non-toxic prey. In contrast, the growth rate of S. acuminatum was unaffected by H. akashiwo. Both Favella sp. and S. acuminatum ingested H. akashiwo but selected against the alga when other prey was available. In addition, natural planktonic communities, collected from East Sound, Orcas Island, northern Puget Sound, in September and October 2007, were exposed to bloomlevel concentrations of H. akashiwo. Abundances of the major microzooplankton types, primarily ciliates and Gyrodinium/Gymnodinium dinoflagellates, were unaffected by H. akashiwo, although slight changes in grazer size structure did occur. Heterosigma akashiwo was harmful to the smallest grazers, mainly aloricate ciliates and small Gyrodinium/Gymnodinium dinoflagellates, and beneficial to larger Gyrodinium/Gymnodinium dinoflagellates that were able to ingest and grow on the alga. The alga was not consumed by the majority of grazers. Preferential feeding on alternate prey reduces toxic effects of H. akashiwo on microzooplankton. Avoidance of H. akashiwo by a major group of grazers would promote bloom formation by reducing H. akashiwo mortality and focusing community grazing pressure on potential competitor species.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Growth and grazing of microzooplankton in response to the harmful alga Heterosigma akashiwo in prey mixtures

Graham¹,

Strom²

2010

Aquat. Microb. Ecol.

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“…They are known to be harmful to other plankton (e.g. Clough & Strom 2005) and fish (e.g. Hiroishi et al 2005) and have often caused large-scale fish mortality rates in the ABSTRACT: We investigated feeding by the raphidophytes Chattonella ovata, C. subsalsa, Fibrocapsa japonica, and Heterosigma akashiwo on the cyanobacterium Synechococcus sp.…”

Section: Introductionmentioning

confidence: 99%

Feeding by raphidophytes on the cyanobacterium Synechococcus sp.

Jeong¹,

Seong²,

Kang³

et al. 2010

Aquat. Microb. Ecol.

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“…will reject captured H. akashiwo cells (Taniguchi and Takeda 1988;Stoecker et al 1995), and will discriminate against H. akashiwo in prey mixtures (Graham and Strom 2010). However, when H. akashiwo is ingested by Favella sp., mortality of the ciliate rapidly follows (Verity and Stoecker 1982;Clough and Strom 2005;Graham and Strom 2010).…”

Section: Discussionmentioning

confidence: 99%

“…Experimental evidence on the grazing response of heterotrophic protists to H. akashiwo is varied. Laboratory research has shown that the heterotrophic dinoflagellates Oxyrrhis marina, Noctiluca scintillans, and Stoeckeria algicida feed readily on H. akashiwo (Jeong et al 2003;Clough and Strom 2005). However, other protists, such as large ciliates, die when they ingest H. akashiwo cells (Verity and Stoecker 1982;Clough and Strom 2005;Graham and Strom 2010).…”

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confidence: 99%

Avoidance, movement, and mortality: The interactions between a protistan grazer and Heterosigma akashiwo, a harmful algal bloom species

Harvey

Menden‐Deuer

2011

Limnology & Oceanography

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A reduction in predator-induced grazing pressure may be a mechanism that facilitates the formation and persistence of harmful algal blooms. Here, the hypothesis was tested that the heterotrophic ciliate Favella ehrenbergii would use avoidance behaviors to reduce encounters with the toxic bloom-forming alga, Heterosigma akashiwo. Using video and image-analysis, population distributions and three-dimensional movements of F. ehrenbergii and H. akashiwo were quantified in triplicate, hourly for 11 h, at nine horizons in a 1-liter experimental column. The salinity structure in the column was manipulated to include a halocline, resulting in layer formation by H. akashiwo. The ciliate's vertical distributions were restricted to high-salinity waters below the halocline, while H. akashiwo was broadly halo-tolerant and could occupy the whole water column. When observed together, F. ehrenbergii did not avoid layers of H. akashiwo. In the presence of H. akashiwo, F. ehrenbergii mortality rates were higher than in either no prey or beneficial prey controls. Swimming behaviors of F. ehrenbergii were erratic, in response to H. akashiwo, compared to aggregative movements in response to beneficial prey, indicating either a behavioral response or the effect of H. akashiwo toxicity on the ciliate. The inability of F. ehrenbergii to avoid H. akashiwo enhanced predator mortality and may contribute to the survival of the harmful algal bloom species, ultimately promoting the formation of H. akashiwo harmful algal blooms.

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Effects of Heterosigma akashiwo (Raphidophyceae) on protist grazers: laboratory experiments with ciliates and heterotrophic dinoflagellates

Cited by 34 publications

References 57 publications

Growth and grazing of microzooplankton in response to the harmful alga Heterosigma akashiwo in prey mixtures

Growth and grazing of microzooplankton in response to the harmful alga Heterosigma akashiwo in prey mixtures

Feeding by raphidophytes on the cyanobacterium Synechococcus sp.

Avoidance, movement, and mortality: The interactions between a protistan grazer and Heterosigma akashiwo, a harmful algal bloom species

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