How Zurich dolphin researchers make waves in Australia

Twenty years ago, Michael Krützen established a dolphin research team at the University of Zurich’s Irchel campus. But the real roots of its success are two research stations in Shark Bay, around 800 kilometres north of Perth. SRF

The University of Zurich regularly makes headlines with its dolphin research in Western Australia. The latest data is particularly striking: the dolphins are under stress, and climate change is their greatest threat. Genetic analyses of the animals and their environment lay the facts bare.

Did you know that dolphins can use tools and pass on knowledge culturally? Or that male dolphins form gangs to abduct females for mating? It may come as a surprise, but many of the facts we know about dolphins today come from research done in a landlocked country – Switzerland. The University of Zurich has been studying dolphin behaviour on Australia’s west coast for over 40 years, with its findings often making waves worldwide.

“For me, it’s like coming home. Out here [in Australia], I feel much more like a biologist than I did back in Zurich,” Michael Krützen told Swiss public television, SRF, which visited him and his team for a major feature on their research.

“If I just sat in the office, many good ideas wouldn’t be born,” Krützen said. “It’s only when I’m onsite with the team, seeing the dolphins in the sea and experiencing this environment, that the new and exciting research projects for the coming years take shape.”

Shark Bay dolphins hunt with tools

In Shark Bay in Western Australia, certain dolphins put a sponge over their snout while foraging, using it to scour the seabed and catch the fish which have been flushed out.

The dolphins are called “spongers”, and their behaviour hasn’t be observed anywhere else in the world. Thanks to genetic analyses, evolutionary biologist Krützen discovered that all “spongers” descend from the same maternal line.

Apparently, a female dolphin invented the technique and then passed it on to her young. And these in turn pass it on to their offspring. This means that not only humans or apes pass on knowledge culturally, but also dolphins – further proof of the intelligence of marine mammals.

Krützen is the driving force behind the research that has put the University of Zurich at the forefront of international dolphin studies. He first travelled as a young student in 1996 to Shark Bay – an ecological paradise and UNESCO World Heritage Site which covers an area half the size of Switzerland. The bay is home to 3,000 dolphins, one of the largest populations in the world, and has been a research hotspot ever since.

Shark Bay

Shark Bay is located around 800 kilometres north of Perth on Australia’s west coast.

© OpenStreetMap contributors

Twenty years ago, Krützen established his own dolphin research team at the University of Zurich’s Irchel campus. However, the roots of its success lie in two research stations in Shark Bay, around 800 kilometres north of Perth. Now 56, Krützen is a professor of evolutionary anthropology and head of the corresponding institute at Irchel. He spends several weeks each year at the research stations in Australia.

Dolphin DNA via an air rifle

Krützen soon realised that pure observations are not enough in reseraching dolphin behaviour. The evolutionary biologist began collecting DNA samples in order to analyse the relationships in the Shark Bay population. He had a special air rifle made, which is still in use today: it’s used to shoot a biopsy dart from a boat to extract a small amount of tissue from the dolphin’s flank.

The dart, which causes just a brief and painless puncture, then floats on the water and is collected. The genetic analyses of these samples have proved invaluable in dolphin research – now more than ever.

A game-changer: DNA

Svenja Marfurt is now responsible for collecting dolphin biopsies in Australia and analysing them in Zurich. The 30-year-old evolutionary geneticist is fascinated by the insights she can extract from dolphin DNA. “That little piece of skin and fat holds endless potential for us,” she says. Thanks to her lab work, the doctoral student has reconstructed the origins of the Shark Bay dolphin population, dating back 12,000-15,000 years.

While not a vast timespan in evolutionary terms, this knowledge helps Zurich researchers better understand the dolphins’ ability to adapt to ongoing climate change.

Extreme weather events are becoming more frequent and prolonged. Most marine mammals struggle to cope with shifting environmental conditions. However, some dolphins in Shark Bay are under less pressure – these are the ones that use tools.

Climate stress

In 2011, a marine heatwave exposed the vulnerability of Shark Bay’s vast ecosystem. Within a short time, water temperatures rose by up to 4°C, with devastating consequences. A third of the world’s largest seagrass beds perished, dealing a severe blow to the biodiversity that depends on them for shelter and hunting – dolphins included.

The dolphin population suffered increased mortality rates, and females gave birth to fewer calves. The situation has still not fully stabilised, as the latest data from the Zurich research team reveals.

How much has climate change altered the dolphins’ habitat? What is happening to Shark Bay’s biodiversity? Which environmental shifts impact the dolphins the most?

To answer these questions, environmental geneticist Manuela Bizzozzero employs a cutting-edge method: environmental DNA, or e-DNA. By analysing local water samples, she can bring a snapshot of the ocean’s life into the university laboratory. “Environmental DNA provides an incredible amount of information in a short time. As a cost-effective and non-invasive tool, it has enormous potential for monitoring marine biodiversity,” she says.

By combining her e-DNA analyses with satellite data, the 30-year-old doctoral student has created detailed maps of Shark Bay’s marine environment. For the first time, researchers can map the dolphins’ preferred habitats and track the availability of their prey in a warming climate.

The maps also reveal why dolphins that hunt with sponges on their snouts fare better. The “spongers” feed in the deep channels of Shark Bay, less affected by marine heatwaves.

For Krützen and his team, many questions remain about the future of the animals. Their habitat is changing rapidly, and the effects of climate change are intensifying. One thing is certain: the dolphins of Shark Bay are under climate stress. Thanks to cutting-edge research from Zurich, this is now clearly visible.

Translated from German using DeepL/amva