We spoke with Denisse Dalgo, PhD Candidate at Leipzig University, who collaborates on the Iguanas from Above project, about her work investigating the impact of El Niño on marine iguanas.
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What drew you to work in Galapagos and focus your PhD on marine iguanas?
My fascination with the Galapagos Islands began with their role in the history of evolutionary science. The Islands’ unique set of environmental conditions, breathtaking landscapes and endemic species of flora and fauna set them apart from all the other Archipelagos.
As an Ecuadorian biologist with a deep interest in marine ecosystems, studying one of the most emblematic and endemic species in Galapagos, the marine iguana, was an opportunity I wasn’t prepared to miss. Their extraordinary adaptation to marine life presents a perfect case study for examining evolutionary biology, behavioural ecology and environmental adaptation, making them an ideal focus for my PhD research.
Marine iguanas are endemic to the Galapagos Islands and are the only sea-going lizards in the world
Why is the marine iguana the only species of iguana to feed on algae?
The marine iguana is the only species of iguana that feeds on algae because they have been exposed to adaptive pressures to forage in the ocean. This species evolved from land iguanas that arrived in Galapagos 4.5 million years ago. Due to the volcanic origin of the Archipelago, early habitats on the Islands were likely arid and barren with minimal terrestrial vegetation as a food source.
As a result of these environmental conditions, these iguanas had to adapt to a sea-faring life to search for food and survive. These adaptations include their long-flattened tails and blunt heads to aid swimming, sharp claws to grip onto rocks and salt glands which expel salt from their bodies.
Discover the extraordinary evolutionary history of the marine iguana
We know Galapagos is currently feeling the effects of El Niño; what impact is this climatic event having on marine iguanas, and how can we use technology to monitor this impact?
El Niño creates significantly warmer water conditions in the Galapagos Islands that reduce the availability of the marine iguana’s primary food source, algae. Historically, El Niño events have led to malnutrition, weight loss and increased mortality rates in marine iguana populations.
During a recent expedition, we observed some individuals with signs of poor health, likely linked to this reduced food availability. This scarcity may also affect their reproductive success, leading to lower mating rates and decreased offspring survival.
To effectively monitor the impact of this year’s El Niño on marine iguanas, technology is our ally. We are using drones for aerial surveys to assess population density, distribution and habitat conditions without disturbing the animals. We are also applying non-invasive genetic and molecular tools. By collecting faecal samples and using genetic markers, we can identify the primary algal species being consumed and assess changes in dietary composition compared to previous years. This enables us to track how iguanas are adapting their foraging habits in response to the altered availability of algae.
El Niño events impact all areas of Galapagos in both the terrestrial and marine environments, leading to considerable impacts on the Islands’ species
What’s one piece of advice you would give to someone just starting their career in conservation?
As a researcher, my work is crucial for understanding the complex interactions among species and their habitats. I consider myself someone who works and takes part in conservation, and I recognise the importance of multidisciplinary teams for the success of conservation strategies. Understanding social, economic and political factors is necessary to safeguard species and habitats from threats including pollution, climate change, habitat destruction and invasive species.
My advice to someone starting their career would be to not be afraid to make use of innovative methods and technology and make sure to engage people in monitoring biodiversity.
It’s crucial to remember that we, as humans and societies, are an integral part of the ecosystem. Conservation work can sometimes feel daunting and frustrating as it often seems like we’re up against overwhelming odds and never doing enough. However, remember that conservation demands patience and foresight and is the result of the persistent and dedicated efforts of individuals and teams alike. Each effort, no matter how small, contributes to a larger and impactful mission.
Each effort, no matter how small, contributes to a larger and impactful mission.
What are your favourite terrestrial and marine Galapagos species and why?
I love so many species in the Galapagos, but I have a soft spot for iguanas!
Even though I’ve never seen a pink land iguana in person, I’m fascinated by them and their unique pink colour. It’s amazing to think that they were only described as a distinct species relatively recently and are found exclusively on the slopes of Wolf Volcano on Isabela. This makes them one of the rarest reptiles in the world. I’d love to see them one day and who knows, study their speciation processes and diet!
When it comes to marine species, I must stick to the marine iguana, although technically it is both terrestrial and marine. I’ve spent countless hours watching them and I’ve grown to love them more and more. I admire how they survive and thrive in such a tough environment. They endure crashing waves just to secure a meal. Despite their harsh living conditions, they’re very relaxed around humans and their hatchlings are the cutest critters you’ll ever see! Marine iguanas are a testament to the incredible adaptability of life on the Galapagos Islands!
Discover the amazing diversity of wildlife that makes the Archipelago so special
