By: Corey Buhay
Dr. Stephen Walsh is planning a 15-day cruise through the Galapagos Islands off the coast of Ecuador.
It’s not a pleasure cruise by any means. Walsh is a geographer, one of 10 scientists on board taking measurements for a range of disciplines – from ocean chemistry to veterinary science. Walsh’s work primarily involves remote sensing, or using satellites that detect different characteristics of the planet below.
Satellites can be used for more than just Google Earth-style photos. They can sense infrared radiation and use it to report sea surface temperature. They use the color of the ocean to calculate how much photosynthesis is going on at its surface. Satellites can even give information about the height of ocean waves and the types of vegetation on land.
Walsh has been doing this sort of work in the Galapagos for some time, but the reason the cruise is happening now is because an El Niño is coming through. That’s an opportunity Galapagos scientists can’t miss.
El Niño events bring warmer water into the marine ecosystem, and for the Galapagos, that can be devastating. The islands are not a tropical paradise. They might be on the equator, but the water around them is cold. This is because of a phenomenon called upwelling.
When ocean currents meet a continental shelf or a volcanic platform – like the Galapagos Platform – the currents slosh up the sides, bringing cold water from the depths to the surface. What’s more, as the earth spins, ocean water parts at the equator and peels off to either side. This is primarily caused by northwest and southwest moving trade winds. The parting surface layer makes room for more cold water to gush up from the deeper ocean.
Deep ocean water contains all the dissolved nutrients that have sunk out of the reach of the plankton, fish, and fauna that reside in the warmer surface waters. When all those rich, well-chilled nutrients come to the top, both marine and coastal critters have a hay day. This is also why the Galapagos experience such high offshore productivity (translation: lots of happy algae and ocean plants).
All this changes when an El Niño hits the islands. The warm spell brings warmer water, heat and rain, which boosts onshore productivity and turns the cactus-spotted volcanic rock into a verdant jungle.
Offshore, however, warm temperatures shut off upwelling, and the cold, nutrient-laden water can’t circulate through the islands. Algae can die off, and the marine iguanas and fish that eat it can’t survive in large numbers. The sea lions that eat the fish grow hungry and emaciated. In short, The influx of warm water throws the whole the food chain out of whack, with implications for many of the iconic species of the Galapagos Islands
That’s the main trouble with global warming in the Galapagos – not sea level rise, but the increased frequency of El Niño events. The islands are a delicate place, and they’re already strained by tourism and fishing industries. The science cruise Walsh is planning could help scientists quantify that strain.
Walsh’s involvement in the Galapagos began in 2011. He was first invited to the islands by some contacts in the Ecuadorian Ministry of the Environment and The Nature Conservancy in Ecuador. He had worked with them previously (studying land use in the Ecuadorian Amazon) but this time they were interested in his ability to identify patches of invasive plants with satellite data.
Walsh left for the Galapagos with his then doctoral student Carlos Mena, a native Ecuadorian, and Brian Frizzelle from the Carolina Population Center.
“So the three of us went down with all our gadgets and gear. We wandered around for about ten days,” Walsh said.
The group travelled with representatives and collaborators from the Galapagos National Park, the Nature Conservancy and other Ecuadorian governmental organizations. The islands, long called “The Enchanted Islands,” made an impression on Walsh and his team, and not only because of the exotic plants and animals.
“It’s also a challenge; [the Galapagos Islands] are in crisis in many ways,” Walsh said.
Walsh realized that his own work could be augmented and strengthened by other research disciplines. He saw this as an opportunity for UNC to step in and help a World Heritage Site threatened by social and ecological disturbances.
By initiating the Center for Galápagos Studies on campus and the Galapagos Science Center on the islands, Steve Walsh has brought UNC to the forefront of the problem. The science cruise is one way Walsh, Dr. Carlos Mena, UNC’s Dr. Adrian Marchetti, and other scientists from both Ecuador and North Carolina can collect baseline data.
Having such data will prove important when scientists want to compare data before and after this year’s El Niño event and during future climatic events, oil spills, or other natural disasters.
The cruise combines the specialties of many scientists to take an interdisciplinary approach to solving scientific problems.
“I’ve been very fortunate over the years to work with interdisciplinary scientists across the spectrum: social, natural, spatial, and computational sciences,” Walsh said. “They leave their imprint as you learn and do, but you can also reach out to these people who are interested in very interesting kinds of questions.”
That’s how he first found himself working with diverse crews of researchers in locations like Glacier National Park, the Amazon rainforest, rural Thailand and the Galapagos Islands – not because he had an itch to travel but because those were the places with the best examples of the phenomena he wanted to study.
The thing about viewing landscapes from space is that the zoomed-in bits look remarkably similar. At least, that’s what I see. For Walsh, the world is a variegated place with different themes and patterns lacing the whole surface.
Walsh uses these satellite data and computer software to create representations of those patterns, which can give important clues about the processes that shaped them – like urbanization or deforestation.
“My job in the Amazon was to map and then model deforestation patterns and to try to understand the drivers of change in the amazon,” Walsh said.
There, he managed to integrate far-off data, collected through satellites high above the planet, with the intensely intimate data gathered from surveys of local peoples about why they might choose to deforest or sell their land. Collecting the data was an adventure.
“I’ve run into some boas, we’ve rented dugout canoes to float down rivers, and we’ve stayed with indigenous communities,” Walsh said.
For Walsh, the adventure is just part of the job. He’s always loved being outside, being active, so for him it’s natural that he fell into that sort of work.
“I enjoy the field work, I enjoy going out with my students whether it be loaded with equipment or making measurements in some interesting alpine meadow,” he said.
"I think that’s the kind of geographer I am, and for me that’s the best way I can work."