Accomplishments & Reports: Spatial Distribution of Viruses in the Palmer-LTER Region

Viruses have been identified as dynamic components in several aquatic environments including marine and fresh waters. High abundances and rapid changes in viral abundance along with rapid viral decay rates suggest that viruses may play an important role in controlling microbial populations. Viruses are also thought to be involved in carbon transfer within the microbial loop, however their quantitative role in carbon and nutrient cycling has not been fully established.

Viruses have previously been observed in the Southern Ocean and abundances have been reported for the Drake Passage (Smith et al. 1992) and for the coastal waters of Paradise Harbour (Bird et al. 1993). During cruise 94-01 of the R/V Polar Duke (Jan 94) we enumerated viruses from surface water samples taken at each station of the Palmer Long Term Ecosystem Research (PAL-LTER) transect lines 300, 400, 500 and 600 (Waters and Smith 1992). Our objective was to determine onshore-to-offshore gradients in viral abundance, and to compare these results with other physical, chemical and microbiological characteristics of the surface waters. Viruses were counted in different size classes by head capsid diameter (<30 nm, 30-60 nm, 60-80 nm, >80 nm), in order to determine changes in the viral community composition between sites. Depth profiles of virus samples were taken at the end point stations (nearest to and furthest from shore) of each transect line.

During Project SANTA CLAµS, our initial investigations of Antarctic coastal habitats were continued by in abstentia collections of water, ice and sediment trap particulate matter. Samples were also obtained from the "phytoplankton culture experiments" and across Drake Passage. Preserved materials have recently been transferred to the University of Quebec at Montreal and sample analysis is already underway.

References

Bird, D. F., R. Maranger, and D. M. Karl. 1993. Palmer LTER: Aquatic virus abundances near the Antarctic Peninsula. Antarctic Journal of the United States, 28: 234-235.

Smith, D. C., G. F. Steward, F. Azam, and J. T. Hollibaugh. 1992. Virus and bacteria abundances in the Drake Passage during January and August 1991. Antarctic Journal of the United States, 27: 125-127.

Waters, K. J. and R. C. Smith. 1992. Palmer LTER: a sampling grid for the Palmer LTER program. Antarctic Journal of the United States, 46: 236-238.