Nature-based solutions to combat climate change take a holistic approach that promotes the preservation of biodiversity and ecosystems. While many efforts have focused on planting trees or restoring wetlands, researchers publishing in Trends in Ecology and Evolution December 15 to advocate for the importance of understanding the carbon sequestration potential of the largest animals on the planet – whales. In their paper, the researchers explore how these marine giants can influence the amount of carbon in our air and waters and potentially contribute to the overall reduction of atmospheric carbon dioxide.
“Understanding the role of whales in the carbon cycle is a dynamic and emerging field that can benefit both marine conservation and climate change strategies,” write the authors, led by University of Ottawa biologist Heidi Pearson. Southeast Alaska. “This will require interdisciplinary collaboration between marine ecologists, oceanographers, biogeochemists, carbon cycle modellers and economists.”
Whales can weigh up to 150 tons, live for over 100 years and are the size of large airplanes. Like all living things, their large biomass is composed largely of carbon and they are one of the largest reservoirs of living carbon in the pelagic ocean, a part of the marine system responsible for storing 22% of the total carbon of Earth.
“Their size and longevity allow whales to exert significant effects on the carbon cycle by storing carbon more efficiently than smaller animals, ingesting extreme amounts of prey, and producing large volumes of waste,” write the authors. authors. “Because baleen whales have some of the longest migrations on the planet, they potentially influence nutrient dynamics and carbon cycling at ocean basin scales.”
Every day, whales consume up to 4% of their body mass in krill and photosynthetic plankton. For the blue whale, this equates to nearly 8,000 pounds. When they have finished digesting their food, their droppings are rich in important nutrients that help krill and plankton thrive, helping to increase photosynthesis and atmospheric carbon storage.
A blue whale can live up to 90 years. When they die and their bodies sink to the bottom of the sea, the carbon they contain is transferred to the deep sea as they decompose. This completes the biological carbon pump, where nutrients and chemicals are exchanged between the ocean and the atmosphere through complex biogeochemical pathways. Commercial whaling, the biggest source of population decline, has reduced whale populations by 81%, with unknown effects on the biological carbon pump.
“Whale recovery has the potential for long-term, self-sustaining enhancement of the ocean carbon sink,” the authors write. “The full carbon dioxide-reducing role of great whales (and other organisms) will only be realized through robust conservation and management interventions that directly support population increases.”
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