Preserving whales can also prove useful in the fight against climate change: these huge and long-lived marine animals can in fact contribute to the reduction of atmospheric carbon dioxide (CO2) by sequestering large quantities of carbon on the seabed.
Their role is reassessed in a study published in the journal Trends in Ecology and Evolution by an international group of experts led by biologist Heidi Pearson of the University of Southeastern Alaska.
Whales can weigh up to 150 tons and live more than 100 years.
Like all living beings, their biomass is largely composed of carbon: for this reason they constitute one of the largest living reserves of carbon in the pelagic ocean, part of the marine system which is responsible for the storage of 22% of the total carbon of the Land.
The role of whales in the carbon cycle (source: Trends in Ecology & Evolution/Pearson)
"Because of their size and longevity, whales exert a strong effect on the carbon cycle by sequestering it more efficiently than smaller animals, ingesting large quantities of prey and producing large volumes of waste products," the researchers explain. " Considering that whales make some of the longest migrations on the planet, they can influence nutrient dynamics and the ocean-scale carbon cycle."
Whales consume up to 4% of their body weight in krill and photosynthetic plankton each day.
At the end of the digestive process they produce excreta rich in important nutrients that help krill and plankton to thrive, promoting the increase of photosynthesis and the accumulation of carbon from the atmosphere.
After death, their carcass sinks to the seabed and releases carbon into the depths as it decomposes.