A humpback whale swims at the surface of the ocean with fish

Many whales have been lost through whaling over the centuries, leading to a loss of nutrients from their poo. Image © Ethan Daniels/Shutterstock

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Artificial whale poo could help restore ocean biodiversity

Suggestions that artificial whale poo could help restore marine biodiversity have been floated recently, ahead of trials set to begin later this year.

But while it could provide a useful stopgap while cetacean populations recover, there is no guarantee the technique, or whales, will ever fully restore what has been lost.

Artificial whale poo could be an unlikely way to restore the oceans of the world.

Rich in nutrients such as phosphorous and nitrogen, whale faeces help to fertilise the upper waters of the ocean and provide the starting point for marine food chains across the world. However, with whale populations reduced to as little as 5% of their historic levels by the impact of whaling, there simply isn't enough to go around.

To prevent the oceans from being caught short, an international team of researchers are set to release artificial whale poo into the Indian Ocean in the coming months, according to New Scientist. The scientists hope to assess whether or not marine biomass regeneration, as the procedure is technically known, is a realistic way to restore the biodiversity of the world's oceans.

Richard Sabin, the principal curator of mammals at the Museum and who is not involved in the trials, says, 'The idea that there could be an artificial way of seeding the ocean's surface is an interesting one. Replacing enough of the whale faeces artificially to be of benefit on a large scale is the issue and the calculations will need to be accurate.

'It requires careful research as it's a big step to release detritus of any kind, including nutrient-rich types, into the ocean to make sure that the balance of nutrients and penetration of sunlight isn't adversely affected.

'It will be a big job, as potentially hundreds of thousands, or even millions, of large whales have been removed from the oceans through whaling, so there's a huge amount of faecal matter that needs replacing. For now, we should let the scientists do their work, and see if they can produce a suitable synthetic replacement.'

A phytoplankton bloom spans the Atlantic Ocean from France to Ireland

Some phytoplankton blooms are so large they can be seen from space. Image © Jeff Schmaltz/MODIS Rapid Response Team, licensed under CC BY 2.0 via Flickr

What is ocean seeding?

Releasing nutrients of this kind into the ocean is an example of a technique known as ocean seeding, or ocean fertilisation.

It aims to provide nutrients to the ocean in areas where concentrations are low, with the aim of stimulating the growth of organisms such as phytoplankton to achieve aims such as taking carbon dioxide out of the atmosphere or building up fish stocks.

While there has been a great deal of scientific attention has been given to the topic, results have been mixed. There are also concerns oceans seeding could have detrimental impacts on the environment, such as deoxygenating water and blocking sunlight from penetrating into the ocean.

In 2008, this led to the introduction of a United Nations moratorium on large commercial ocean seeding projects until the risks are better understood. However, small scale research projects are still permitted.

This research project aims to find out if replicating natural processes, rather than creating artificial ones, could be key to making ocean seeding work. It aims to replace the whale poo that was formerly provided by hundreds of thousands, or even millions, of whales which no longer exist because of human hunting in previous centuries.

Whale poo floats on the surface of the ocean

Whale poo's colour results from the diet of the animals. Image © Eric Gropp, licensed under CC BY 2.0 via Flickr

What has whale poo ever done for us?

While whale poo may seem like an esoteric choice, it has a significant impact on the world's ecosystems. Nutrients from it help the Amazon to grow, while a 2010 study estimated that sperm whales in the Southern Ocean alone remove 200,000 tonnes of carbon from the atmosphere each year.

'A whale can't generally defecate underwater because of the water pressure,' Richard explains, 'so they go to the surface to do so. When large whales defecate, they produce a huge faecal plume. It's made of semi-solid material that floats, and it is released into the photic zone of the ocean where it fertilises the waters for phytoplankton.'

The trials will take place in the Indian Ocean, which is a highly diverse area. In particular, many large cetaceans, including blue, fin and sei whales, are all found in its waters.

Their poo will be replicated using waste rice husks, loaded with the nutrients required to simulate whale faeces. This will then be floated out to sea, where it is hoped they will provide food to fish populations in the Indian Ocean. These fish in turn can then become food for large whales, beginning the cycle again.

If successful, researchers hope that whale populations will eventually recover enough to take over this ecosystem service once more. However, Richard says that this is not as easy as sitting back and waiting.

Watch Richard discuss his research into stressors which affect whales by looking at their earwax.

'Whales are in a precarious position, and affected by so many more things than they were 100 years ago,' he says. 'There are far more stressors in the ocean now that didn't exist then, with levels of chemical pollutants and anthropogenic noise having increased significantly.

'These long-term stressors have an impact on the ability of whales to reproduce, and while seeding open oceans will probably have some benefit, it probably won't lead to a return to pre-industrial whaling populations alone.

'While some species, like the humpback whale, are doing remarkably well and have even moved into areas vacated by other cetaceans, others aren't. We're really only just beginning to comprehend the effects of removing keystone species like whales from the ocean.

'It really depends on us, and how our actions continue to affect the oceans. If our negatives continue to outweigh the positives, then we won't see a return to those pre-commercial whaling population levels.'

The trials are expected to begin within months, with the results likely to be pored over in the coming years.