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Zooplankton feeding on the nuisance flagellate Gonyostomum semen.

Johansson KS, Vrede T, Lebret K, Johnson RK - PLoS ONE (2013)

Bottom Line: The large bloom-forming flagellate Gonyostomum semen has been hypothesized to be inedible to naturally occurring zooplankton due to its large cell size and ejection of long slimy threads (trichocysts) induced by physical stimulation.In a grazing experiment using radiolabelled algae and zooplankton collected from lakes with recurring blooms of G. semen and lakes that rarely experience blooms, we found that Eudiaptomus gracilis and Holopedium gibberum fed on G. semen at high rates, whereas Daphnia cristata and Ceriodaphnia spp. did not.Grazing rates of E. gracilis were similar between bloom-lakes and lakes with low biomass of G. semen, indicating that the ability to feed on G. semen was not a result of local adaptation.

View Article: PubMed Central - PubMed

Affiliation: Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden. karin.johansson@slu.se

ABSTRACT
The large bloom-forming flagellate Gonyostomum semen has been hypothesized to be inedible to naturally occurring zooplankton due to its large cell size and ejection of long slimy threads (trichocysts) induced by physical stimulation. In a grazing experiment using radiolabelled algae and zooplankton collected from lakes with recurring blooms of G. semen and lakes that rarely experience blooms, we found that Eudiaptomus gracilis and Holopedium gibberum fed on G. semen at high rates, whereas Daphnia cristata and Ceriodaphnia spp. did not. Grazing rates of E. gracilis were similar between bloom-lakes and lakes with low biomass of G. semen, indicating that the ability to feed on G. semen was not a result of local adaptation. The high grazing rates of two of the taxa in our experiment imply that some of the nutrients and energy taken up by G. semen can be transferred directly to higher trophic levels, although the predominance of small cladocerans during blooms may limit the importance of G. semen as a food resource. Based on grazing rates and previous observations on abundances of E. gracilis and H. gibberum, we conclude that there is a potential for grazer control of G. semen and discuss why blooms of G. semen still occur.

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Ingestion rates.Ingestion rates (cells ind−1 min−1) of zooplankton from the four different lakes feeding on A) G. semen and B) P. subcapitata. Lakes Bäen and Älgarydssjön have a history of recurring G. semen blooms whereas Hagasjön and St Skärsjön usually have low biomasses of G. semen. Bars not connected by the same letter are significantly different from each other (one way ANOVA with Tukey’s HSD comparisons, p<0.05). The H. gibberum sample comprised only one replicate and was not included in the statistical analysis. Error bars represent standard deviation.
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pone-0062557-g001: Ingestion rates.Ingestion rates (cells ind−1 min−1) of zooplankton from the four different lakes feeding on A) G. semen and B) P. subcapitata. Lakes Bäen and Älgarydssjön have a history of recurring G. semen blooms whereas Hagasjön and St Skärsjön usually have low biomasses of G. semen. Bars not connected by the same letter are significantly different from each other (one way ANOVA with Tukey’s HSD comparisons, p<0.05). The H. gibberum sample comprised only one replicate and was not included in the statistical analysis. Error bars represent standard deviation.

Mentions: The calanoid copepod E. gracilis fed on G. semen with an average ingestion rate of 1.3 cells ind−1 min−1 (Fig. 1A), corresponding to a daily (24 h) ingestion of 0.047 mm3 ind−1 d−1. In the one treatment containing H. gibberum, this species showed a similar ingestion rate to the copepods (1.5 cells ind−1 min−1, Fig. 1A, corresponding to 0.053 mm3 ind−1 d−1). By contrast, the average ingestion rates of D. brachyurum, D. cristata, and Ceriodaphnia spp. were 0.041, 0.032, and 0.018 cells ind−1 min−1, respectively (Fig. 1A). These ingestion rates correspond to 0.0015, 0.0012, and 0.00066 mm3 ind−1 d−1. Possibly, the radioactive signal in small cladocerans reflects feeding on parts of broken G. semen cells and/or bacteria that had been labelled by consumption of algal exudates.


Zooplankton feeding on the nuisance flagellate Gonyostomum semen.

Johansson KS, Vrede T, Lebret K, Johnson RK - PLoS ONE (2013)

Ingestion rates.Ingestion rates (cells ind−1 min−1) of zooplankton from the four different lakes feeding on A) G. semen and B) P. subcapitata. Lakes Bäen and Älgarydssjön have a history of recurring G. semen blooms whereas Hagasjön and St Skärsjön usually have low biomasses of G. semen. Bars not connected by the same letter are significantly different from each other (one way ANOVA with Tukey’s HSD comparisons, p<0.05). The H. gibberum sample comprised only one replicate and was not included in the statistical analysis. Error bars represent standard deviation.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3646948&req=5

pone-0062557-g001: Ingestion rates.Ingestion rates (cells ind−1 min−1) of zooplankton from the four different lakes feeding on A) G. semen and B) P. subcapitata. Lakes Bäen and Älgarydssjön have a history of recurring G. semen blooms whereas Hagasjön and St Skärsjön usually have low biomasses of G. semen. Bars not connected by the same letter are significantly different from each other (one way ANOVA with Tukey’s HSD comparisons, p<0.05). The H. gibberum sample comprised only one replicate and was not included in the statistical analysis. Error bars represent standard deviation.
Mentions: The calanoid copepod E. gracilis fed on G. semen with an average ingestion rate of 1.3 cells ind−1 min−1 (Fig. 1A), corresponding to a daily (24 h) ingestion of 0.047 mm3 ind−1 d−1. In the one treatment containing H. gibberum, this species showed a similar ingestion rate to the copepods (1.5 cells ind−1 min−1, Fig. 1A, corresponding to 0.053 mm3 ind−1 d−1). By contrast, the average ingestion rates of D. brachyurum, D. cristata, and Ceriodaphnia spp. were 0.041, 0.032, and 0.018 cells ind−1 min−1, respectively (Fig. 1A). These ingestion rates correspond to 0.0015, 0.0012, and 0.00066 mm3 ind−1 d−1. Possibly, the radioactive signal in small cladocerans reflects feeding on parts of broken G. semen cells and/or bacteria that had been labelled by consumption of algal exudates.

Bottom Line: The large bloom-forming flagellate Gonyostomum semen has been hypothesized to be inedible to naturally occurring zooplankton due to its large cell size and ejection of long slimy threads (trichocysts) induced by physical stimulation.In a grazing experiment using radiolabelled algae and zooplankton collected from lakes with recurring blooms of G. semen and lakes that rarely experience blooms, we found that Eudiaptomus gracilis and Holopedium gibberum fed on G. semen at high rates, whereas Daphnia cristata and Ceriodaphnia spp. did not.Grazing rates of E. gracilis were similar between bloom-lakes and lakes with low biomass of G. semen, indicating that the ability to feed on G. semen was not a result of local adaptation.

View Article: PubMed Central - PubMed

Affiliation: Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden. karin.johansson@slu.se

ABSTRACT
The large bloom-forming flagellate Gonyostomum semen has been hypothesized to be inedible to naturally occurring zooplankton due to its large cell size and ejection of long slimy threads (trichocysts) induced by physical stimulation. In a grazing experiment using radiolabelled algae and zooplankton collected from lakes with recurring blooms of G. semen and lakes that rarely experience blooms, we found that Eudiaptomus gracilis and Holopedium gibberum fed on G. semen at high rates, whereas Daphnia cristata and Ceriodaphnia spp. did not. Grazing rates of E. gracilis were similar between bloom-lakes and lakes with low biomass of G. semen, indicating that the ability to feed on G. semen was not a result of local adaptation. The high grazing rates of two of the taxa in our experiment imply that some of the nutrients and energy taken up by G. semen can be transferred directly to higher trophic levels, although the predominance of small cladocerans during blooms may limit the importance of G. semen as a food resource. Based on grazing rates and previous observations on abundances of E. gracilis and H. gibberum, we conclude that there is a potential for grazer control of G. semen and discuss why blooms of G. semen still occur.

Show MeSH
Related in: MedlinePlus