Everything makes sense in the life cycle of the world’s oceans: dead mussels, dead plant remains, even faeces. Whale excrements act like a natural dung. That´s the reason why these impressive animals are also called “gardeners of the seas”. The marine mammals feed in the depths, especially on krill. Later they excrete the digested food in the form of faeces, preferably on the water surface. These faeces contain important nutrients for plants and animals. The nitrogenous faeces of the whales fertilize the water near the surface with large amounts of nitrate and iron, which in turn drastically increases the amount of phytoplankton and krill. This affects the ocean food chain and promotes fish growth and biodiversity.
Another benefit of poo
As a nice side effect, whale excrements in the water could even slow down climate change, a research team from Stanford University in California reported in the journal “Nature” in November last year: As the faeces increases phytoplankton amounts, the amount of photosynthesis is also higher and therefore, significantly more CO2 from the atmosphere can be absorbed and bound to carbon. Well, this is really a very effective way to mitigate climate change! At the same time, whales are great stores of carbon themselves. When a whale dies, it sinks to the bottom of the sea and remains there for up to hundreds of years. Since the carbon in its carcass is bound in the long term, no climate-damaging CO2 is formed from it.
Repopulate the ocean
As we all know, the number of whales is dramatically decreasing, which also leads to a lack of nutrients from whale excrements. Massive whaling, ever-increasing shipping traffic and ocean pollution are threatening marine mammals. The whale population has plummeted over the past few centuries. Scientists estimate that the number of animals has decreased by 66 to 90 %. This has probably already changed the structure of the oceans. However, previous efforts by the international community to increase the number of whales in the oceans again failed. On the contrary: the number of whales continued to fall.
According to recent studies, the world’s remaining great whales store around nine million tons less carbon as a direct result of whalehunting. Alternatively, a gradual recovery in whale populations would mean removing around 200,000 tons of carbon per year, roughly equivalent to the CO₂ storage of 110,000 hectares of forest.
We are trying to repopulate the ocean… I don’t know whether the experiment will be the final answer. I’m very attracted to the idea that after a while… if the whale population [recovers], we can leave the whales as the biological pump.
For all the challenges we face, nature has a solution
As it seems rather unrealistic in the current situation that whale stocks will return to their original level, the scientists want to start experiments with artificial faeces in the Indian Ocean.
What the artificial whale faeces will be made of is yet to be decided, but iron-rich sand or volcanic ash are two options being considered. Key will be ensuring it offers the right mix of nitrates, silicates, phosphates and iron, according to King. The material will be loaded onto baked rice husks – a factory waste product – which will act as rafts to carry the material on the sea surface.
The experiment will be small-scale and last for only a few weeks, to see if the rice husks are good faeces-deliverers. For marine biomass regeneration to make a difference to fish numbers and carbon removal, this kind of approach will need to be undertaken at huge scale. Similar approaches could lock billions of tons of CO2 away each year. Humanity emits about 40 billions of tons each year.
This great scientific approach falls under the field of biomimicry. Biomimicry is a practice that learns from and mimics the strategies and engineering found in nature in order to solve the world’s most pressing challenges and ensure a sustainable future for all life on earth.