The change in environmental conditions in the Canadian basin during the time series from 2004 to 2012; (A) A map of the Arctic Ocean showing the station locations (circles) included in this study; (B) variability in summer sea ice extent in the Arctic Ocean; data comes from the National Snow and Ice Data Center; (C) the latitudinal gradient of sea surface salinity over the time series; (D) stratification index, error bars indicate standard deviation between stations; (E) ratio of picophytoplankton to nanophytoplankton; (F) bacterioplankton. In panels E and F, values are the average of all measurements > 15 m depth and salinity < 31 PSU, and error bars indicate the standard error between depths and between stations. Credit: ISME communication (2024). DOI: 10.1093/ismeco/ycad004
The Arctic region is experiencing climate change at a much faster rate than the rest of the world. Melting ice caps, runoff from thawing permafrost, and other factors are rapidly changing the composition of Arctic Ocean water. And this change happens down to the microbial level.
In a study conducted by Concordia and published in the journal ISME communication, researchers analyzed archival samples of bacteria and archaea populations collected from the Beaufort Sea, on the border of northwest Canada and Alaska. The samples were collected between 2004 and 2012, a period that included two years – 2007 and 2012 – in which sea ice coverage was historically low. The researchers examined samples taken from three water levels: the summer mixed layer, the high Arctic waters below, and the Pacific source waters at the deepest level.
The study examined the genetic makeup of microbes using bioinformatics and statistical analysis over a nine-year period. Using this data, researchers were able to see how changing environmental conditions influenced the structure and function of organisms.
The researchers discovered subtle but statistically significant changes in the communities studied.
“We observed an overall loss of species diversity across all different water bodies,” says David Walsh, a professor in the Department of Biology and corresponding author of the paper.
“We also saw changes in microbial community composition, meaning there were different species after the 2007 sea ice minimum compared to before.”
However, periods of decline in population wealth changed between layers of ocean water. A sudden drop in the level of cooler mixed summer waters, between 3 and 9 meters deep, was observed in 2005-2007. The high Arctic waters, between 16 and 78 meters, experienced a decline between 2010 and 2012, while the deeper water layer of the Pacific, between 49 and 154 meters, experienced a decline in two stages: once between 2005 and 2007 and again between 2010 and 2012.
The researchers are careful not to overstate the results of their findings, saying the changes, while significant, remain small. But as the Arctic’s summer ice cover steadily declines from year to year, the data suggests possible trends that could be visible in future population studies in recent years.
“The warming and cooling of the Arctic Ocean is leading to a decline in nutrients important for photosynthesis, which produces the organic matter that serves as a source of energy and carbon for the marine food web,” says Walsh.
“This change risks reinforcing what is known as the microbial loop, in which energy and carbon that would normally go to higher trophic levels, i.e. zooplankton then fish, are rapidly recycled by micro-organisms. This ecosystem is already dominated by microbial processes, which will only become stronger as this system continues.”
“This study gives us a basic idea of what is happening in the Arctic,” says co-author Arthi Ramachandran. “The Arctic is warming four times faster than the rest of the world, making it a fascinating ecosystem to study. The oceans are all interconnected and the physical barriers of these oceans are increasingly less defined.”
The researchers are currently 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 better understand the diversity and functioning of microbial communities in the environment.
More information:
Susanne A Kraemer et al, A multi-year time series (2004-2012) of bacterial and archaeal community dynamics in a changing Arctic Ocean, ISME communication (2024). DOI: 10.1093/ismeco/ycad004
Provided by Concordia University
Quote: Researchers identify decline in microbial genetic richness in the western Arctic Ocean (February 13, 2024) retrieved February 13, 2024 from
This document is subject to copyright. Apart from fair use for private study or research purposes, no part may be reproduced without written permission. The content is provided for information only.