The Milne Fiord Epishelf Lake is a rare freshwater lake that floats over the Arctic Ocean, locked in place only by a layer of ice, less than 500 miles from the North Pole. Single-celled organisms, particularly cyanobacteria, predominate in the lake and are regularly infected by strange “giant viruses.”
Researchers from Université Laval in Québec, Canada, have created the first estimation of the viral abundance in this lake. The study has been published in the American Society for Microbiology journal Applied and Environmental Microbiology.
Since single-celled microorganisms which are predominate in polar aquatic habitats are commonly infected by viruses, viruses are essential to understanding these ecosystems. Few studies have been done on these viruses, their diversity, and their distribution in Milne Fiord Lake. team is currently attempting to sequence the enormous viruses, and this study will probably help us understand how the viruses interact with the cyanobacteria they infect to affect the ecology of the lake.
The amount of time left for microbiologists to fully understand the biodiversity and biogeochemical cycles of these ice-dependent habitats, as well as the effects of the quick, irreversible changes in temperature, is rapidly decreasing due to rapidly rising temperatures.
“The ice shelf that holds the lake in place is deteriorating every year, and when it breaks up, the lake will drain into the Arctic Ocean and be lost,” said corresponding author Alexander I. Culley.
“Our results highlight the uniqueness of the viral community in the freshwater lake, as compared to the marine fiord water, particularly in the halocline community,” said Culley.
The ice shelf that holds the lake in place is deteriorating every year, and when it breaks up, the lake will drain into the Arctic Ocean and be lost. Our results highlight the uniqueness of the viral community in the freshwater lake, as compared to the marine fiord water, particularly in the halocline community.
Alexander I. Culley
The halocline is a region where salinity rapidly decreases as the water column is raised. According to him, this environment provides niches for viruses and hosts that are neither present in freshwater nor in marine layers of homogeneous salinity.
When the weather permitted, the only method of transportation to the far-flung lake in the high Arctic was by helicopter. In order to identify the viruses and bacteria present in the lake water, the study team took water samples and sequenced every piece of DNA in it.
The research lays the groundwork for greater comprehension of viral ecology across a range of global habitats, notably in the high Arctic.
“High bacterial abundance coupled with a possible prevalence of lytic lifestyle at this depth suggests that viruses have an important role in biomass turnover,” said Mary Thaler, Ph.D., a member of Culley’s team at Université Laval.
The term “lytic lifestyle” describes how daughter virus particles are released while the host microbial cell is obliterated. The Milne Fiord Epishelf Lake had several significant changes, but a multiyear fall in cyanobacteria quantity was the most notable.
The researchers attributed that drop to the increasing marine influence in the freshwater lake, “since cyanobacteria have very low abundance in the Arctic Ocean,” they wrote.
The specifics of this ecosystem, however, are still unknown because the majority of its viruses have only ever been partially characterized. Because of this, scientists frequently lack knowledge on how viruses affect the microorganisms they infect or about which viruses live in which microbes.
