Mixotrophic Activity and Diversity of Antarctic Marine Protists in Austral Summer
Identifying putative mixotrophic protist species in the environment is important for understanding their behavior, with the recovery of these species in culture essential for determining the triggers of feeding, grazing rates, and overall impact on bacterial standing stocks. In this project, mixotro...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2018-02-01
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| Series: | Frontiers in Marine Science |
| Subjects: | |
| Online Access: | http://journal.frontiersin.org/article/10.3389/fmars.2018.00013/full |
| _version_ | 1811215829517205504 |
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| author | Rebecca J. Gast Scott A. Fay Scott A. Fay Robert W. Sanders |
| author_facet | Rebecca J. Gast Scott A. Fay Scott A. Fay Robert W. Sanders |
| author_sort | Rebecca J. Gast |
| collection | DOAJ |
| description | Identifying putative mixotrophic protist species in the environment is important for understanding their behavior, with the recovery of these species in culture essential for determining the triggers of feeding, grazing rates, and overall impact on bacterial standing stocks. In this project, mixotroph abundances determined using tracer ingestion in water and sea ice samples collected in the Ross Sea, Antarctica during the summer of 2011 were compared with data from the spring (Ross Sea) and fall (Arctic) to examine the impacts of bacterivory/mixotrophy. Mixotrophic nanoplankton (MNAN) were usually less abundant than heterotrophs, but consumed more of the bacterial standing stock per day due to relatively higher ingestion rates (1–7 bacteria mixotroph−1 h−1 vs. 0.1–4 bacteria heterotroph−1 h−1). Yet, even with these high rates observed in the Antarctic summer, mixotrophs appeared to have a smaller contribution to bacterivory than in the Antarctic spring. Additionally, putative mixotroph taxa were identified through incubation experiments accomplished with bromodeoxyuridine-labeled bacteria as food, immunoprecipitation (IP) of labeled DNA, and amplification and high throughput sequencing of the eukaryotic ribosomal V9 region. Putative mixotroph OTUs were identified in the IP samples by taxonomic similarity to known phototroph taxa. OTUs that had increased abundance in IP samples compared to the non-IP samples from both surface and chlorophyll maximum (CM) depths were considered to represent active mixotrophy and include ones taxonomically similar to Dictyocha, Gymnodinium, Pentapharsodinium, and Symbiodinium. These OTUs represent target taxa for isolation and laboratory experiments on triggers for mixotrophy, to be combined with qPCR to estimate their abundance, seasonal distribution and potential impact. |
| first_indexed | 2024-04-12T06:29:02Z |
| format | Article |
| id | doaj.art-51cc4260c4f04560b0fd6c1caeec2a07 |
| institution | Directory Open Access Journal |
| issn | 2296-7745 |
| language | English |
| last_indexed | 2024-04-12T06:29:02Z |
| publishDate | 2018-02-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Marine Science |
| spelling | doaj.art-51cc4260c4f04560b0fd6c1caeec2a072022-12-22T03:44:03ZengFrontiers Media S.A.Frontiers in Marine Science2296-77452018-02-01510.3389/fmars.2018.00013297659Mixotrophic Activity and Diversity of Antarctic Marine Protists in Austral SummerRebecca J. Gast0Scott A. Fay1Scott A. Fay2Robert W. Sanders3Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA, United StatesBiology Department, Temple University, Philadelphia, PA, United StatesInvitae, San Francisco, CA, United StatesBiology Department, Temple University, Philadelphia, PA, United StatesIdentifying putative mixotrophic protist species in the environment is important for understanding their behavior, with the recovery of these species in culture essential for determining the triggers of feeding, grazing rates, and overall impact on bacterial standing stocks. In this project, mixotroph abundances determined using tracer ingestion in water and sea ice samples collected in the Ross Sea, Antarctica during the summer of 2011 were compared with data from the spring (Ross Sea) and fall (Arctic) to examine the impacts of bacterivory/mixotrophy. Mixotrophic nanoplankton (MNAN) were usually less abundant than heterotrophs, but consumed more of the bacterial standing stock per day due to relatively higher ingestion rates (1–7 bacteria mixotroph−1 h−1 vs. 0.1–4 bacteria heterotroph−1 h−1). Yet, even with these high rates observed in the Antarctic summer, mixotrophs appeared to have a smaller contribution to bacterivory than in the Antarctic spring. Additionally, putative mixotroph taxa were identified through incubation experiments accomplished with bromodeoxyuridine-labeled bacteria as food, immunoprecipitation (IP) of labeled DNA, and amplification and high throughput sequencing of the eukaryotic ribosomal V9 region. Putative mixotroph OTUs were identified in the IP samples by taxonomic similarity to known phototroph taxa. OTUs that had increased abundance in IP samples compared to the non-IP samples from both surface and chlorophyll maximum (CM) depths were considered to represent active mixotrophy and include ones taxonomically similar to Dictyocha, Gymnodinium, Pentapharsodinium, and Symbiodinium. These OTUs represent target taxa for isolation and laboratory experiments on triggers for mixotrophy, to be combined with qPCR to estimate their abundance, seasonal distribution and potential impact.http://journal.frontiersin.org/article/10.3389/fmars.2018.00013/fullprotistdiversitymixotrophyRoss Seaamplicon sequencing |
| spellingShingle | Rebecca J. Gast Scott A. Fay Scott A. Fay Robert W. Sanders Mixotrophic Activity and Diversity of Antarctic Marine Protists in Austral Summer Frontiers in Marine Science protist diversity mixotrophy Ross Sea amplicon sequencing |
| title | Mixotrophic Activity and Diversity of Antarctic Marine Protists in Austral Summer |
| title_full | Mixotrophic Activity and Diversity of Antarctic Marine Protists in Austral Summer |
| title_fullStr | Mixotrophic Activity and Diversity of Antarctic Marine Protists in Austral Summer |
| title_full_unstemmed | Mixotrophic Activity and Diversity of Antarctic Marine Protists in Austral Summer |
| title_short | Mixotrophic Activity and Diversity of Antarctic Marine Protists in Austral Summer |
| title_sort | mixotrophic activity and diversity of antarctic marine protists in austral summer |
| topic | protist diversity mixotrophy Ross Sea amplicon sequencing |
| url | http://journal.frontiersin.org/article/10.3389/fmars.2018.00013/full |
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