Unveiling 1,200 years of human occupation in Canada's Arctic

A recent study provides new insights into ancient cultures in Canada's Arctic, focusing on Paleo-Inuit and Thule-Inuit peoples over thousands of years. Jules Blais, professor of biology at the University of Ottawa, and a team of researchers detected human presence and settlements on Somerset Island, Nunavut, by analyzing sediment samples.

The Arctic has been home to various cultures, such as the Paleo-Inuit (2500 BCE to 1250 CE) and the Thule-Inuit (1200 to 1500 CE). Although historical evidence is scarce, this recent study provides valuable insight into their presence.

The study discovered evidence of Paleo-Inuit presence on Somerset Island in Nunavut, Canada, where it was lacking.

The innovative research methodologies revealed detailed information about past human history without traditional artifacts.

Professor Jules Blais says, "By analyzing pond sediment samples, we were able to construct detailed histories of site occupation. This includes clear evidence of Paleo-Inuit presence and indications that the Thule-Inuit arrived earlier than previously estimated."

The research used archeological evidence and sedimentary biomarkers to study prehistoric settlement on Somerset Island.

Sediment cores from island ponds were analyzed for trace elements and organic compounds.

Results showed that the Thule-Inuit population increased from the 13th to 15th centuries.

The researchers also showed high levels of metals like lead, copper, zinc and nickel in twentieth-century sediment, suggesting air pollution during that time.

Blais says, "We used generalized additive models (GAMs) and radiocarbon dating techniques to identify key time points in the sediment record corresponding to the expected dates of Thule-Inuit arrival and site abandonment. This approach allowed us to detect periods of significant change in sediment proxies, providing a chronological framework for understanding the history of human occupation on the island."

This research underscores the importance of interdisciplinary approaches in archeology and highlights the significance of sedimentary archives in reconstructing past human activities and environmental conditions.

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Decline in microbial genetic richness in the western Arctic Ocean

The Arctic region is experiencing climate change at a much faster rate than the rest of the world. Melting ice sheets, runoff from thawing permafrost and other factors are rapidly changing the composition of the Arctic Ocean's water. And that change is being experienced all the way down to the microbial level.

In a Concordia-led study published in the journal ISME Communications, researchers analyzed archival samples of bacteria and archaea populations taken from the Beaufort Sea, bordering northwest Canada and Alaska.

The samples were collected between 2004 and 2012, a period that included two years -- 2007 and 2012 -- in which the sea ice coverage was historically low.

The researchers looked at samples taken from three levels of water: the summer mixed layer, the upper Arctic water below it and the Pacific-origin water at the deepest level.

The study examined the microbes' genetic composition using bioinformatics and statistical analysis across the nine-year time span.

Using this data, the researchers were able to see how changing environmental conditions were influencing the organisms' structure and function.

The researchers found subtle but statistically significant changes in the communities they studied.

"We observed a general overall loss in diversity of species across all the different water masses," says David Walsh, a professor in the Department of Biology and the paper's corresponding author.

"We also saw changes in the composition of the microbial community, meaning there were different species after the 2007 sea ice minimum than before."

However, the periods of population richness decline changed between the ocean's layers of water.

Sudden decline in the fresher summer mixed water level, between 3-9 meters deep, was observed in 2005-2007.

The upper Arctic water, between 16-78 metres, saw declines in 2010-2012, while the deeper Pacific water layer, between 49-154 meters, experienced a two-step decline -- once between 2005-2007 and again between 2010-2012.

Small beginnings

The researchers are taking care not to overemphasize the results of their findings, saying the changes, while significant, remain slight.

But with the summer Arctic ice cover shrinking steadily year over year, the data does hint at possible trends that may be visible in upcoming population studies in more recent years.

"With the warming and freshening of the Arctic Ocean comes a decrease of nutrients that are important for photosynthesis, which produces the organic matter that serves as energy and carbon sources for the marine food web," Walsh explains.

"This shift risks strengthening what is known as the microbial loop, in which the energy and carbon that would normally go into higher trophic levels -- meaning zooplankton and then fish -- is rapidly recycled by microorganisms. This ecosystem is already dominated by microbial processes, which will only get stronger as this system continues."

"This study provides us with a baseline idea of what is happening in the Arctic," says co-author Arthi Ramachandran, PhD 23. "The Arctic is warming four times faster than the rest of the world, which makes it a fascinating ecosystem to study. The oceans are all interconnected, and the physical barriers of these oceans are becoming much less defined."

Looking into the ocean's warmer, fresher future

The researchers are now planning a metagenomic study that extends the time series to cover periods of even more intense sea ice minima.

They hope to fully sequence the organisms' genomes to further understand the microbial communities' diversity and function in the environment.

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