Research at Newnham: Why rotting seal is the smell of success

When Cota heads out to do her research, she has two options. There’s the boat, “which takes 32 hours on a good day – it’s never a good day,” or a 6-seater plane, which flies bumpily 670 km across the South Pacific. 

Once on the islands, she swings a special cooler backpack onto her back, and clambers over the rocks and out into the fur seal colonies of the Juan Fernandez Archipelago. There, she’ll gather up fur seal faeces, and pack them away into the sampling pack (at least they’re kept cool), for later analysis. Lately she’s branched out from faeces, and has begun to collect bones from dead and decaying fur seals too.

“the only person working on this sentinel species in the world”

Cota assures us, “You start associating the smell with something positive – you know that you’ve done a good day’s work.”

This is because PhD student Cota Toro Valdivieso is using the Juan Fernandez fur seal as a ‘sentinel species’ to monitor the health of this isolated archipelago; one of 11 irreplaceable priority sites for marine conservation worldwide. Once considered extinct, the seals are now flourishing, and by using non-invasive sampling techniques Cota can track environmental issues in their habitats. That’s where the bones come in.

As an apex predator, fur seals allow her to monitor the health of the whole food chain. Analysing bones lets her investigate the levels of heavy metals that the fur seals are ingesting and so the levels in the food chain. She is the only person working on this species in the world, and her data is feeding into multiple environmental research projects.

From Chile to Cambridge: 8 years of determination

The longest journey, however, has been the one that led a vet from Chile to become a PhD student at Newnham.

It was during her veterinary studies in Chile that she first realised that monitoring seals could help monitor and preserve this UNESCO Biosphere Reserve. But Chile offered little opportunity for research of this kind.

For 7 years, Cota wrote to academics around the world, seeking a place to do her research. “The only person who welcomed me was Barbara,” she said.

“The only person who welcomed me was Barbara”

Newnham Fellow Dr Barbara Blacklaw saw the huge potential in Cota’s suggestion, and was determined to make it work. Cota came to the UK, and Barbara agreed to be her PhD supervisor. So then it was merely a matter of Cota winning a full four-year PhD scholarship. She began to develop her lab skills, interning in Barbara’s lab. Meanwhile, she supported herself working in the St Catharine’s College kitchens.

The first year she applied, she was unsuccessful. Someone less determined would have given up, especially with a career as a vet as an option. Instead, she continued her catering work, applied again, and was awarded a prestigious Chilean scholarship.

The scholarship still doesn’t cover the cost of the research – for that, Cota and Barbara are using their ingenuity, juggling grants, and even turning (successfully) to crowdfunding. Two years into her PhD, she’s gathered material over several journeys to Juan Fernandez, and is about to move onto sustained lab analysis.

What fur seals reveal about their environment

Each fur seal’s faeces are analysed using advanced genetic techniques to identify the seal’s microbiome – the types of micro-organisms living in the seal. Analysing the microbiome of sentinel species is becoming an important tool to support conservation efforts.

“an early warning system that ecosystems are in danger”

Environmental contamination, loss of food sources, and habitat degradation result in a disruption of animals’ immune system, and an increased susceptibility to fatal disease. Traditionally, it’s only when sentinel species begin dying in unusual numbers that humans recognise the environmental problem. However, the microbiome will demonstrate changes before the animals become diseased – so monitoring the microbiome acts as an early warning system that ecosystems are in danger.

Cota is already talking to government bodies in Chile, to persuade them that economic development must go hand in hand with environmental conservation.

“I had to go all the way to the UK to work on seals in my own country,” Cota laughs. “But I always wanted to be a vet who worked with wildlife. I never saw myself working in a room.”

So gathering up seal faeces is not only a good day’s work for Cota, but for the people and species of this unique archipelago. From all of us who love the world’s diverse environments, thank you!

You can follow the latest from Cota’s life and research at