Climate in the Islands of Change
Updated: Oct 5
When you hear “Galapagos,” what comes to mind? Lumbering giant tortoises? Deep and cold, turquoise waters? Sea lions lounging with marine iguanas?
Of all the things that come to mind, there is one principle that unites them all—uniqueness driven by evolution. Due to the Galapagos’ isolation, volcanic origin, and relative youth, the 127 islands, islets, and rocks forming the archipelago boast a uniquely high level of endemism—species found nowhere else on earth. There are 2,909 marine species that have been identified in the Galapagos, and of these, more than 520 are endemic.
Charles Darwin noted descriptions of speciation in the finches and mockingbirds of the islands - species which had adapted over millions of years to survive in the habitats and microclimates of each island. The volcanic slivers of land known as the Galapagos Islands lie above the boundaries of three tectonic plates, and at the confluence of three major Pacific Ocean currents. It's this fortunate geological and geographical location of the islands that makes them unique.
For many, the islands conjure images of iconic species like the Galapagos giant tortoises, but the heart of the ecosystem lies within the oceans surrounding the islands. It is this marine ecosystem that is changing most rapidly as climates shift, and the viability of all species revolves around what will happen next.
Many climate scientists agree that at minimum, due to increasing warming in both the atmosphere and the ocean, the Galapagos will experience more impactful El Niños (although a prediction of their overall frequency remains elusive). But before we can think about the effects of El Niños, we have to understand the normal flow of the ocean in and around the Galapagos.
The Pacific Equatorial Undercurrent (EUC) is one of the three major Pacific Ocean currents converging on the Galapagos. Trade winds blow warm surface waters at the equator en masse from east to west, right up against the western shores of the Pacific. These massive volumes of warm surface water exert pressure on the cold water below, launching the subsurface EUC back east across the ocean.
The equatorial trade winds deposit a whole lot of warm water in the West Pacific: enough to drive the cold subsurface EUC more than 8,000 miles from Papua New Guinea to the Galapagos—where it smashes directly into the two largest islands, Isabela and Fernandina. The cold, nutrient-rich water provides the foundation of a robust marine food chain.
During an El Niño, trade winds die down for reasons still not fully understood by scientists. When the trade winds relent, they don’t heap up as much warm water in the West Pacific, meaning that there’s not as much pressure exerted on the cooler waters beneath. With less pressure, the EUC diminishes, and with it, the marine nutrients – potentially crashing the entire ecosystem. During the El Niño in 1982, an estimated 77% of Galapagos penguins died and in 1997, some marine iguana populations lost 90% of their individuals. On land, increased rain associated with El Niño years creates ideal conditions for the spread of invasive plant species, creating a foreign floral landscape for the iconic Galapagos giant tortoises.
Populations have been creeping back after the most recent El Niños. But if El Niños will become more intense—as climate models predict—will the genetic variability present in the remaining populations of these incredible creatures be enough to survive?
Ecology Project International isn’t taking chances. For sixteen years we have offered local and visiting youth and teachers the opportunity to make a positive impact on climate-threatened species and ecosystems in the Galapagos. Thanks to a unique partnership with Galapagos National Park, students work with park rangers to locate, monitor, and tag giant tortoises to understand their movements through the islands.
Galapagos tortoises are migratory species. In the warm and wet season, the tortoises exploit the vegetation of the lowlands. In the cool and dry season, they trudge up the volcanic slopes, where the garúa, or sea mist, develops and provides the needed moisture for the higher elevation flora. A warming climate may reduce the annual garúa, decreasing the moisture available for high elevation vegetation that the tortoises depend on.
EPI Galapagos Island Ecology course participants also study the tortoises’ role in seed dispersal for invasive species like the blackberry. The Galapagos is home to 590 native plant species—but as of 2017, there were 810 invasive plant species. Because of the tortoises’ migratory paths between elevations they act as vectors for invasive plant species, sowing the seeds of their own fate.
Last year, EPI students helped locate and collect biometric data on 122 giant tortoises with the Galapagos National Park. More than 22,000 seeds were identified in tortoise dung, allowing scientists to better understand what tortoises are eating and how their diets might alter the landscape. EPI students are also critical to service projects restoring native flora to the islands, clearing blackberry, guava, and cascarilla from an endemic grove of daisy trees (Scalesia pedunculata), and replanting native species covering more than an acre just last year. For over five years, EPI's alumni group, the Mola Mola Eco Club, has led community education programs around nesting green sea turtles at Tortuga Bay.
Local conservation leaders emerge from our courses empowered and full of ideas to make positive change in their communities.
Although much of the focus of the Galapagos Island Ecology programs are on sea turtles and giant tortoises, each student group also censuses pieces of the Galapagos Marine Reserve for fish species, tallying more than 4,600 individuals last year, allowing scientists to gain a better picture of species diversity throughout the reserve.
The incredible species of the Galapagos have faced millennia of intense environmental conditions, from exploding volcanoes to abrupt shifts in oceanic temperatures via El Niño.
Even as climate change threatens to make these conditions more intense, Ecology Project International students and teachers intend to continue to help them thrive long into the future.
For information on how you can get involved, visit our website.