Grantee Research Project Results
2002 Progress Report: Viruses as a Regulator of Harmful Algal Bloom Activity: Aureococcus anophagefferens as a Model System
EPA Grant Number: R829367Title: Viruses as a Regulator of Harmful Algal Bloom Activity: Aureococcus anophagefferens as a Model System
Investigators: Gastrich, Mary Downes , Anderson, O. Roger , Wilhelm, Steven W. , Gobler, Christopher
Current Investigators: Gastrich, Mary Downes , Anderson, O. Roger , Gobler, Christopher , Wilhelm, Steven W.
Institution: Columbia University in the City of New York , University of Tennessee , Long Island University - Southampton College
Current Institution: Columbia University in the City of New York , Long Island University - Southampton College , University of Tennessee
EPA Project Officer: Packard, Benjamin H
Project Period: January 15, 2002 through July 31, 2005 (Extended to January 14, 2006)
Project Period Covered by this Report: January 15, 2002 through July 31, 2003
Project Amount: $210,232
RFA: Ecology and Oceanography of Harmful Algal Blooms (2001) RFA Text | Recipients Lists
Research Category: Water Quality , Water , Aquatic Ecosystems
Objective:
The objectives of this research project are to: (1) determine the frequency of viral-like particles (VLPs) that infect and lyse natural populations of Aureococcus anophagefferens in coastal bays of New York and New Jersey; (2) isolate viruses specific to A. anophagefferens and establish baseline information on the genetic diversity of viruses that infect A. anophagefferens; and (3) determine the influence of viral activity on the proliferation of A. anophagefferens and bloom termination in situ.
Progress Summary:
The combined results of this study and previous studies clearly show continuing evidence of a persistent viral infection of natural populations of A. anophagefferens occurring over a regional geographic range over several bloom years. The sampling frequency in 2002 provided a better definition of the different stages of the bloom in Little Egg Harbor, NJ, and our transmission electron microscopy (TEM) results clearly characterized the percentage of VLP-infected A. anophagefferens in natural populations throughout the bloom period (e.g., elevated percentages at the beginning of the bloom, sharply decreased percentages during the peak of the bloom, and up to 60 percent of infected cells as the bloom subsided). Although these results also corroborated previous studies, our research provided additional evidence of an increased percentage of VLP-infection at the end of the bloom.
Our laboratory results confirmed the lytic activity of the viral isolates from New Jersey and New York waters that were specific to A. anophagefferens in situ, and our TEM results confirmed the presence of intracellular VLPs in healthy cultures infected with the lytic virus. These results corroborated previous studies of reinfection experiments of viral isolates from New York waters. Our TEM results showed that at least two types of viruses (ca. 70 nm capsids) were present in unpurified viral isolates that caused the lysis of some healthy cultures of A. anophagefferens. This finding corroborates previous studies viral lysis of A. anophagefferens, including similar sized free viruses, but this will be further investigated during the next project year.
Future Activities:
Future activities will focus on Objectives 2 and 3. Activities related to Objective 2-viral detection and isolation, will include: (1) the determination of measurements (e.g., abundance of isolated viruses specific to Aureococcus infecting A. anophagefferens, kinetics of isolated purified viruses adsorption to host cells, estimated in situ decay rate of isolated and purified viral infectivity); (2) growing cultures of A. anophagefferens under optimal conditions for growth as previously determined; (3) obtaining ultrastructural data, using TEM, to document and quantify the stages of viral infection, including viral attachment to the host cell (an algal cell), internal replication, and the fate of the host cell, using several clones of A. anophagefferens.
We also will determine the genetic diversity in viruses infecting A. anophagefferens by providing an approximation of the genetic diversity among the viruses isolated that infect A. anophagefferens, and we will distinguish between different operational taxonomic units (OTUs) by restriction fragment length polymorphism analysis of their genomes. We also will determine the duration of the lytic cycle and determination of visible TEM infection period to infer mortality (e.g., time-course examination of A. anophagefferens cultures through a controlled infection and lysis). TEM will be used to visibly determine the viral infection period to infer mortality of natural populations of A. anophagefferens as per methods used to obtain preliminary results above. In addition, we will conduct one-step growth curves. We also will complete field experiments (Objective 3) and conduct experiments to determine if our propagated viral isolates are capable of lysing field populations of A. anophagefferens.
Journal Articles:
No journal articles submitted with this report: View all 8 publications for this projectSupplemental Keywords:
viruses, brown tide blooms, Aureococcus anophagefferens., RFA, Scientific Discipline, Water, Ecosystem Protection/Environmental Exposure & Risk, Ecology, Aquatic Ecosystems & Estuarine Research, Ecosystem/Assessment/Indicators, Ecosystem Protection, Chemistry, Environmental Microbiology, Aquatic Ecosystem, Ecological Effects - Environmental Exposure & Risk, algal blooms, Biology, mortality rate, harmful algal blooms, control of algal blooms, Auerococcus, brown tide blooms, ECOHAB, water qualityProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.