Whales transport vital nutrients from urine, placentas, carcasses and sloughing skin across oceans that help to keep marine ecosystems healthy, a study has revealed.
Researchers found that these life-supporting nutrients are generated in the animals’ summer feeding habitats and then carried long distances as they travel to winter breeding grounds.
This involves travelling from high-latitude (polar) areas such as Alaska and Antarctica to low-nutrient tropical grounds such as Hawaii and the Caribbean.
The study, published in Nature Communications on Monday, said it marks the longest known transport of nourishment by mammals on the planet.
These nutrients help to fuel phytoplankton growth, which are tiny plants that absorb vast amounts of carbon and produce oxygen that play a critical role in the marine food web.
Researchers looked at whales’ input of nutrients from urine, skin, dead bodies and poo at the Hawaiian Islands Humpback Whale National Marine Sanctuary.
They found that the whales had brought more nitrogen from their feeding grounds than the ocean’s natural processes, such as currents and upwellings.
Overall, the study said migrating gray, humpback and right whales convey an estimated 3,784 tons of nitrogen and 46,512 tons of biomass to low-nutrient coastal areas in the tropics and subtropics every year, many of which have coral reef ecosystems.
Joe Roman, report author and whale expert, said: “If plants and phytoplankton are the planet’s lungs, taking in carbon dioxide and expelling oxygen, then whales and other animals are like the circulatory system.
“Known as the great whale conveyor belt, this movement of nutrients through the ocean can have a big impact on marine ecosystems.”
The study, partly funded by marine charity Whale and Dolphin Conservation with an international research team, comes after a huge decline in whale populations in the past centuries because of commercial whaling.
Numbers are recovering in some areas of the world as countries ban commercial hunting but this study strengthens the argument for their protection, the researchers said.
