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Persistence of Algal Viruses and Cya...

Long, Andrew Milam.

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Persistence of Algal Viruses and Cyanophages in Freshwater Environments.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Persistence of Algal Viruses and Cyanophages in Freshwater Environments./
作者:	Long, Andrew Milam.
出版者:	Ann Arbor : ProQuest Dissertations & Theses, : 2017,
面頁冊數:	173 p.
附註:	Source: Dissertation Abstracts International, Volume: 79-04(E), Section: B.
Contained By:	Dissertation Abstracts International79-04B(E).
標題:	Ecology. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10256391
ISBN:	9780355448238

Persistence of Algal Viruses and Cyanophages in Freshwater Environments.
Long, Andrew Milam.

Persistence of Algal Viruses and Cyanophages in Freshwater Environments. - Ann Arbor : ProQuest Dissertations & Theses, 2017 - 173 p.

Source: Dissertation Abstracts International, Volume: 79-04(E), Section: B.

Thesis (Ph.D.)--University of Toronto (Canada), 2017.

Algal viruses and cyanophages exert top-down population controls upon primary producers in aquatic environments. Despite their clear importance, many ecological phenomena related to viruses are poorly understood. For instance, several studies suggest that phytoplankton viruses often exist at stable abundances, even when their hosts are absent. However, estimates of algal virus and cyanophage decay suggest that they decay too swiftly for these stable abundance patterns to occur. This paradox is the primary impetus for my research. In order to begin to address this knowledge gap, the seasonality of algal virus decay was assessed using decay incubation experiments across all four seasons using infectivity assays with cultivated viruses to estimate decay rates, which found high decay rates in the summer and spring and low decay rates in the winter. This seasonal study found that the low algal virus decay rates during winter allowed for survival after 126 days under ice cover in a seasonally frozen freshwater pond. This work was expanded upon by developing and validating molecular assays to estimate decay of environmental viruses with either unknown or uncultivated hosts, which represent the majority of viruses in nature. Upon validation of molecular assays for estimating decay rates, environmental algal virus and cyanophage decay rates were found to vary seasonally in the same way that cultivated algal virus decay rates did. Further, environmental algal viruses were found to have lower decay rates than cyanophages. In the molecular study, viruses were also found to persist in the winter under/within the ice cover for 126 days. However, the spring and summer decay rates estimated in both studies were often too high to permit virus population maintenance for long periods without ongoing production, which would require the presence of host cells at relatively high abundances. As such, the ability of freshwater sediment to serve as an environmental refugium for phytoplankton viruses was assessed using molecular methods. Freshwater sediments from Lake Erie were found to harbor diverse assemblages of both algal viruses and cyanophages. Some algal virus and cyanophage genotypes were found at high abundances in putatively 50 year old sediments, suggesting that sediments may aid in the persistence of viruses. In conclusion, over-wintering of algal viruses in the water column appears to be one mechanism that maintains a viral 'seed-bank,' and the sediments of aquatic environments may be an environmental refugium for algal viruses and cyanophages alike.

ISBN: 9780355448238Subjects--Topical Terms:

516476
Ecology.

Persistence of Algal Viruses and Cyanophages in Freshwater Environments.
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