Whales play a much more important role than previously thought in ocean balance. A recent study has precisely quantified their contribution to nutrient recycling.
Researchers have particularly focused on baleen whales, a group that includes blue whales, fin whales, and humpback whales. These marine giants release significant amounts of nitrogen, phosphorus, and trace elements through their feces. The study, published in the
Proceedings of the National Academy of Sciences, measured these releases in different species and modeled their effects on the marine ecosystem.
Primary productivity, meaning the ability of phytoplankton to produce organic matter through photosynthesis, is significantly boosted by these nutritional inputs. In some areas of the North Sea, this increase can reach 10% during summer months. The nutrients released by whales act as a true marine fertilizer, particularly valuable in regions far from coasts where terrestrial inputs are limited.
The effects of this natural fertilization propagate throughout the entire food chain. Zooplankton, those small organisms that feed on phytoplankton, see their biomass increase by up to 10%. This abundance then benefits fish and marine mammals, creating a virtuous cycle. Norwegian salmon and herring, for example, directly depend on this increased productivity for their survival and growth.
Beyond its impact on marine life, this phenomenon plays a role in climate regulation. Phytoplankton photosynthesis captures atmospheric carbon dioxide and transforms it into organic compounds. Thus, by promoting phytoplankton growth, whales indirectly participate in carbon sequestration, helping to mitigate the effects of climate change.
These discoveries highlight the crucial importance of protecting whale populations. Their presence benefits not only their own species, but the entire ocean ecosystem. Future research will refine these models by incorporating more data on cetacean movements and nutrient dynamics in different marine regions.
Phytoplankton, the engine of the oceans
Phytoplankton represents all the plant microorganisms that float in marine waters. These microscopic organisms are capable of performing photosynthesis, a process that transforms light energy into chemical energy.
These microalgae form the base of virtually all ocean food chains. Their abundance determines the biological richness of a marine area. Without phytoplankton, oceans would be biological deserts incapable of supporting the marine life we know.
Their growth mainly depends on three factors: sunlight, water temperature, and nutrient availability. Areas where these three conditions are optimal see the development of what are called phytoplankton blooms, true explosions of microscopic life.
These organisms also play a fundamental role in the planetary carbon cycle. By absorbing atmospheric CO2, they help regulate Earth's climate. Part of the carbon they fix eventually sediments to the ocean floor, where it can remain stored for millennia.