Newswise) Researchers discovered that the two-year-old heatwave, also known as the Blob, may have temporarily reduced the Pacific’s biological pump. This is the mechanism that shuttles carbon from the ocean’s surface to the deep ocean where it can be stored for many millennia.
Canadian, European, and U.S. Department of Energy Joint Genome Institute researchers conducted a large scale study of how one of the most severe marine heatwaves in recorded history – commonly known as the Blob– affected Pacific Ocean microorganisms. The researchers found that abrupt temperature changes affect not only larger marine life.
“Heatwaves such as the Blob may decrease the ocean’s biological role as a carbon sink for fixed atmospheric carbon,” said Dr. Steven Hallam (he/him), a microbiologist at the University of British Columbia and author of the paper published in Nature Communications Biology.
This ‘biological pump’ process is an important mechanism for buffering the impact of human activity on Earth’s climate, said co-author Dr. Colleen Kellogg (she/her), a research scientist with the Hakai Institute. “The ocean is a large global reservoir of atmospheric carbon dioxide. If marine heatwaves reduce the capacity for carbon dioxide to be absorbed into the ocean, then this shrinks this reservoir and leaves more of this greenhouse gas in the atmosphere.”
Microbes form the base of the marine food web, performing critical functions such as synthesizing and recycling organic matter. Although little is known about the effects of marine heatwaves on these invisible members of the community, it can be a crucial indicator for the rest.
“Marine heatwaves are one of the big challenges of climate change,” explains Dr. Sachia Traving (she/her), lead author on the study at the University of Southern Denmark. Understanding how heatwaves affect microbes, which are some of the most common and smallest organisms on the planet, will allow us to understand how future heatwaves will impact our oceans .”
. The study brought together researchers from UBC and Fisheries and Oceans Canada’s Institute of Ocean Sciences and the Hakai Institute. To chart the structure of microbial communities before and after the severe marine heatwave, they combined seven years worth of DNA sequencing with oceanographic measurements taken from an open-sea buoy called Ocean Station Papa (OSP).
OSP serves as the terminal station for the Line P transect. The longest-running oceanographic time series is 1956, LineP. It is made up of 26 stations that are hydrographic stations and travel westward towards OSP. This is over 1 ,400km from the coast.
The Blob began in 2013, and saw a significant increase in microbes that can survive in nutrient-limited conditions. This shift is likely due to changes in the region’s phytoplankton composition, which saw a decrease in large cells that help to form organic matter particles. This decrease in large particles hinders the ocean’s biological pump and ability act as a carbon sink.
Research shows that marine heatwaves can be a result of climate change. As global temperatures rise, these anomalous warm bodies of water are becoming more frequent and disrupt ecosystems. The Blob’s impacts on life in Northeastern Pacific Ocean have been documented by previous research. This includes phytoplankton, fish populations, and marine mammals and birds.
The current research extends these impacts on the microbial foodwebs that underlie carbon transport and sequestration within the ocean, while reinforcing and enhancing the need for continuous time series measurements to better forecast the effects of climate change upon essential ecosystem functions.
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